Tag Archives: False Positives

AfibAlert Versus AliveCor/Kardia: Which Mobile ECG Device Is Best At Accurately Identifying Atrial Fibrillation?

The skeptical cardiologist has been testing the comparative accuracy of two hand-held mobile ECG devices in his office over the last month. I’ve written extensively about my experience with the AliveCor/Kardia (ACK) device here and here. Most recently I described my experience with the Afib Alert (AA) device here.

Over several days I had my office patients utilize both devices to record their cardiac rhythm and I compared the device diagnosis to the patient’s true cardiac rhythm.

Normal/Normal

In 14 patients both devices correctly identified normal sinus rhythm. AFA does this by displaying a green check mark , ACK by displaying the actual recording on a smartphone screen along with the word Normal.

The AFA ECG can subsequently uploaded via USB connection to a PC and reviewed in PDF format. The ACK PDF can be viewed instantaneously and saved or emailed as PDF.

 

Normal by AFA/Unreadable or Unclassified by AliveCor

In 5 patients in normal rhythm (NSR) , AFA correctly identified the rhythm but ACK was either unreadable (3) or unclassified (2). In the not infrequent case of a poor ACK tracing I will spend extra time adjusting the patient’s hand position on the electrodes or stabilizing the hands. With AFA this is rarely necessary.

In this 70 year old man the AFA device recording was very good and the device immediately identified the rhythm as normal.

Chaput AFA SR

ACK recording was good quality but its algorithm could not classify the rhythm.

GC Unclassified

A 68 year old man who had had bypass surgery and aortic valve replacement had a very good quality AFA recording with correct classification as NSRChaput AFA SR

AliveCor/Kardia recordings on the same patient despite considerable and prolonged efforts to improve the recording were poor and were classified as “unreadable”

Scott AC unreadable
Alivecor tracing shows wildly varying baseline with poor definition of p wave

 

False Positives

There were 3 cases were AFA diagnosed atrial fibrillation (AF) and the rhythm was not AF. These are considered false positives and can lead to unncessary concern when the device is being used by patients at home. In 2 of these ACK was unreadable or unclassified and in one ACK also diagnosed AF.

A 90 year old woman with right bundle branch block (RBBBin NSR was classified by AFA as being in AF.

VA AFA read as AF
Slight irregularity of rhythm combined with a wider than normal QRS from right bundle branch block and poor recording of p waves likely caused AFA to call this afib
VA unclassified RBBB
AliveCor tracing calls this unclassified. The algorithm does not attempt to classify patients like this with widened QRS complexes due to bundle branch block.

The ACK algorithm is clearly more conservative than AA. The ACK manual states:

If you have been diagnosed with a condition that affects the shape of your EKG (e.g., intraventricular conduction delay, left or right bundle branch block,Wolff-Parkinson-White Syndrome, etc.), experience a large number of premature ventricular or atrial contractions (PVC and PAC), are experiencing an arrhythmia, or took a poor quality recording it is unlikely that you will be notified that your EKG is normal.

 

One man’s rhythm confounded both AFA and AC. This gentleman has had atrial flutter in the past and records at home his rhythm daily using his own AliveCor device which he uses in conjunction with an iPad.IMG_8399.jpg

During our office visits we review the recordings he has made. He was quite bothered by the fact that he had several that were identified by Alivecor as AF but in fact were normal.

Screen Shot 2017-05-06 at 11.48.47 AM
These are recordings Lawrence made at home that i can pull up on my computer. He makes a daily recording which he repeats if he is diagnosed with atrial fibrillation. In the two cases above of AF a repeat measurement was read as normal. Of the two cases which were unclassified , one was normal with APCs and the other was actually atrial flutter

A recording he made on May 2nd at 845 pm was read as unclassified but with a heart rate of 149 BPM. The rhythm is actually atrial flutter with 2:1 block.

Screen Shot 2017-05-06 at 11.47.37 AM

Sure enough, when I recorded his rhythm with ACK although NSR (with APCS) it was read as unclassified

Screen Shot 2017-05-06 at 11.49.49 AM

AFA classified Lawrence’s rhythm as AF when it was in fact normal sinus with APCs.

AFA Mcgill AF

 

 

One patient a 50 year old woman who has a chronic sinus tachycardia and typically has a heart rate in the 130s, both devices failed.

We could have anticipated that AC would make her unclassified due to a HR over 100 worse than unclassified the tracing obtained on her by AC (on the right)was terrible and unreadable until the last few seconds. On the other hand the AFA tracing was rock solid throughout and clearly shows p waves and a regular tachycardia. For unclear reasons, however the AFA device diagnosed this as AF.

 

 

Accuracy in Patients In Atrial Fibrillation

In 2/4 patients with AF, both devices correctly classified the rhythm..

In one patient AFA correctly diagnosed AF whereas ACK called it unclassified.

This patient was in afib with HR over 100. AFA correctly identified it whereas ACK called in unclassified. The AC was noisy in the beginning but towards the end one can clearly diagnose AFScreen Shot 2017-05-06 at 8.39.06 AMScreen Shot 2017-05-06 at 8.11.53 AM

In one 90 year old man AFA could not make the diagnosis (yellow)

Screen Shot 2017-05-06 at 11.35.40 AM

ACK correctly identified the rhythm as AF

Screen Shot 2017-05-06 at 11.37.51 AM

One patient who I had recently cardioverted from AF was the only false positive ACK. AliveCor tracing is poor quality and was called AF whereas AFA correctly identified NSR>

Screen Shot 2017-05-06 at 8.42.46 AMScreen Shot 2017-05-06 at 8.42.26 AM

 

 

Overall Accuracy

The sensitivity of both devices for detecting atrial fibrillation was 75%.

The specificity of AFA was 86% and that of ACK was 88%.

ACK was unreadable or unclassified 5/26 times or 19% of the time.

 

The sensitivity and specificity I’m reporting is less than reported in other studies but I think it represents more real world experience with these types of devices.

Summary

In a head to head comparison of AFA and ACK mobile ECG devices I found

-Recordings using AfibAlert are usually superior in quality to AliveCor tracings with a minimum of need for adjustment of hand position and instruction.

-This superiority of ease of use and quality mean almost all AfibAlert tracings are interpreted whereas 19% of AliveCor tracings are either unclassified or unreadable.

-Sensitivity is similar. Both devices are highly likely to properly detect and identify atrial fibrillation when it occurs.

-AliveCor specificity is superior to AfibAlert. This means less cases that are not AF will be classified as AF by AliveCor compared to AfibAlert. This is due to a more conservative algorithm in AliveCor which rejects wide QRS complexes, frequent extra-systoles.

Both companies are actively tweaking their algorithms and software to improve real world accuracy and improve user experience but what I report reflects what a patient at home or a physician in office can reasonably expect from these devices right now.

-ACP

Paranoid Rumination From A Freshly-Minted Migraineur

As I sit here writing, I perceive a scintillating band of zig-zags in the shape of a reverse C on the left side of my visual field. I sense the scintillating reverse C with either, or both eyes closed, and I first noted it when the letters in the New Yorker article I was reading became obscured by the C. Attempts to focus on the crescent are futile:  it moves as I move my eyes or head. Within its body are vague browns, blacks and whites, and overall it is reminiscent of an Egyptian or Art Deco piece of art.

I have a friend in Brooklyn, a flaneur, and one in Florida, a raconteur; I have now become a migraineur: one who suffers from migraine headaches or, in my case, the visual or tactile hallucinations known as migraine aura that precede the headaches.

I go to my bookshelf and find Oliver Sacks’ book “Migraine: Understanding a Common Disorder, which I purchased long ago when I was not a migraineur (primarily to complete my collection of Sacks’ unique and brilliant writing).  On page 62, figure 2b, I find a drawing which closely approximates what I’m “seeing.”

An artistic depiction of migraine aura which was similar to mine. Original source is unclear.

I had asked Siri to start the timer on my Apple watch when I first noticed the visual disturbance, and now note that at 16 minutes 32 seconds, my vision was back to normal. At 25 minutes 16 seconds, I experienced a very subtle ache in my left frontal region which persisted for 5 minutes.

I have observed patients with severe migraine headaches: suffering from nausea, intense pain, photosensitivity and requiring dark and sleep and powerful analgesics to cause remission. I am fortunate because my after-aura headaches, if any, are minimal and brief.

The first time I experienced the visual hallucination was five years ago. I was not blogging then, but made a detailed note of the experience, complete with paranoid rumination on brain testing and side effects of MRIs. What follows is the transcript with the comments of the present day skeptical cardiologist in green or red.

“I had a crazy day Thursday. I gave a talk to the echo lab from 7 to 8 AM and then rushed over to the hospital to see the most urgent of the 9 inpatients I had. I had seen 4 patients by the time I got paged to see my first patient in the office. I headed over there and saw 6 patients . Then I hurried back to the hospital to grab the EKGs I was supposed to read that day. I was a little stressed because I needed to read these and try to see more of my inpatients before heading over to the outpatient testing facility which I had to be at by 1230 to supervise stress testing. I sat down in my hospital office and started reading the EKGs. After I had read a few, I became aware of a defect on the left side of my vision. It felt like when you have looked at a bright light and it leaves a residual on your retina.
At first I thought it was due to the fact that i was reading the EKGs with only the desk lamp on my left on. I turned on the overhead light and it didn’t help. I then realized that I had a hockey puck shaped defect in my left visual field in both eyes. When the defect covered key portions of the EKG, I couldn’t read it. It was filled with a jagged, prism like filling. Otherwise I felt fine. My first thought was that I was having a scintillating scotoma and that this was a migraine aura. Other things seemed much less likely-TIA for example. I called Dr S, my favorite neurologist, on his cell phone and told him what was going on. He suggested I visit him in his office right then. His office was in 400 East which would necessitate a right turn from my office. Instead, I took a left turn down to the West office building, took the elevator up to the fourth floor and finally realized my mistake when all I could find were office numbers that ended in W. (At the time young Dr. P felt this disorientation was related to the aura but perhaps it was due to distraction) By the time I reached his office twenty minutes after the visual symptoms started, they had resolved.
Dr. S did a neuro exam and history, and concluded that I most likely had a migraine aura but thought that I should get an MRI to be certain there was no structural brain disease. After I left his office I began feeling slightly nauseated with a slight headache. Over the next two hours the headache became a moderate frontal headache associated with a sense of fatigue.
I got the MRI yesterday and Dr. S thinks it is normal, although the radiologist read it as showing small subcortical defects which could be consistent with “chronic migraine, small vessel disease, or demyelinating process.”
I almost didn’t get the MRI. This is one of the classic situations in medicine where the history and physical alone makes the diagnosis with near certainty (young Dr. P is correct, see what Choosing Wisely says here), but because a very small number of cases might have something more serious (a brain tumor or vascular lesion in this case ), (perhaps also fueled by medical legal concerns and patient’s love of fancy tests) an expensive imaging test is ordered.
If you took 1000 people with my symptoms and the normal neuro exam with low atherosclerotic risk factors, and did brain MRIs on them, the vast majority of findings would be incidental, probably false positives (I believe young Dr. P made up this statistic but the national migraine center in the UK says :

“The main problem with MRI scans is ‘looking for a shilling and finding a sixpence,’ in finding abnormalities that are unrelated to headache, entirely by chance. The risk of a minor abnormality of no medical significance is 1 in 4. The risk of a chance abnormality that might need treatment is about 1 in 40. Once these ‘incidentalomas’ have been found, the patient may then find it difficult to obtain insurance (for example travel) and there is often a temptation to repeat the scan time and time again to check that the ‘incidentaloma’ is not changing..)

False positives lead to unnecessary anxiety in patients and in some cases unnecessary testing (Dr. S told me that he sees tons of patients who have had normal MRIs with readings similar to mine who are convinced they have MS) (MS=multiple sclerosis, a demyelinating process. Although my MRI was read as having abnormalities possibly due to a “demyelinating process” I must not have had one because  6 years later I have had no other symptoms)) and in some cases unnecessary additional testing.

As I was lying in the MRI gantry listening to the “ratatat “of the scanner, I wondered if we really know the consequences of rearranging the molecules of brain tissue with giant magnetic fields.
Dr. S  had ordered the MRI with gadolinium. I recalled seeing adds from law firms seeking “victims” of MRI scans (one man was awarded 5 million dollars after developing nephrogenic systemic fibrosis after one dose of gadolinium (NSF). I knew that gadolinium had been linked to some really serious disorders. The tech had said nothing to me about adverse effects of the “dye” she would be using. My nose began itching like crazy, then my left eyelid. I couldn’t scratch until I emerged from the scanner. After the initial images were done and I was brought out of the scanner, I scratched my face like crazy and asked the tech if there were any side effects from gadolinium.
“Why yes, she said, you can have severe allergic reactions,” but we’ve only had a couple.” Also, she said, there is some disorder… she couldn’t remember the name or what it did but knew that it was only a problem if you had kidney failure or had diabetes and were over the age of 60.
As I was lying in the scanner after receiving the gadolinium, I began trying to estimate what risk I would be willing to assume in this situation. The disease you can get if you have severely impaired kidney function and receive gadolinium is nephrogenic systemic fibrosis.
Would I accept a 1 in 1/1000 chance of NSF in exchange for diagnosing something other than migraine 1/1000 times? I couldn’t and can’t easily and logically make that call. I have no idea how patients can make these decisions.

Cephalgiacally  Yours

-ACP

Here’s a video of an aura similar to mine (one of many posted at visual migraine animation)

Migraine experiences have served as a major source of artistic inspiration in both past and contemporary painters, sculptors, film-makers and other visual artists. Check some of their work out at migraine aura foundation.

 

 

 

Are Your Palpitations Due to Benign PVCs?

If you feel your heart flip-flopping, then you are experiencing palpitations: a sensation that the heart is racing, fluttering, pounding, skipping beats or beating irregularly.

Often, this common symptom is due to an abnormal heart rhythm or arrhythmia.

The arrhythmias that cause palpitations range from common and benign to rare and lethal, and since most individuals cannot easily sort out whether they have a dangerous or a benign problem, they often end up getting cardiac testing or cardiology consultation.

The most common cause of palpitations, in my experience, is the premature ventricular contraction, or PVC (less commonly known as the ventricular ectopic beat or VEB).

Premature Ventricular Contractions-Electrical Tissue Gone Rogue

The PVC occurs when the ventricles of the heart (the muscular chambers responsible for pumping blood out to the body) are activated prematurely.

This video shows the normal sequence of electrical and subsequent mechanical activation of the chambers of the heart.

To get an efficient contraction, the electrical signal and contraction begins in the upper chambers, the atria, and then proceeds through special electrical fibers to activate the left and right ventricles.

Sometimes this normal sequence is disrupted because a rogue cell in one of the ventricles becomes electrically activated prior to getting orders from above. In this situation, the electrical signal spreads out from the rogue cell and the ventricles contract out of sequence or prematurely.

This results in a Premature Ventricle Contraction.

labeled-pvc
p waves represent depolarization and activation of the atria which are followed normally after120 to 200 milliseconds by the QRS complex which represents activation of the ventricles. The PVC (inside red circle) is wider and weirder and disrupts the regular interval between beats (green lines).

I recorded the above AliveCor tracing in my office on a patient who suffers palpitations due to PVCs (we’ll call her Janet).

The wider, earlier beat (circled in red) in the sequence is the PVC. The prematurity of the PVC means that the heart has not had the appropriate time to fill up properly. As a result, the PVC beat pumps very little blood and may not even be felt in the peripheral pulse. Patients with a lot of PVCs, say ocurring every other beat in what is termed a bigeminal pattern, often record an abnormally slow heart rate because only one-half of the heart’s contractions are being counted.

While recording this, every time Janet felt one of her typical “flip-flops,” we could see that she had a corresponding PVC and the cause of her symptoms was made clear.

There is a pause after the PVC because the normal pacemaker of the heart up in the right  atrium (the sinus node) is reset by electrical impulses triggered by the PVC.. The beat after the PVC is more forceful due to a more prolonged time for the ventricles to fill and  Consequently, most  patients feel this pause after the PVC rather than the PVC itself,

PVCs are common and most often benign. I have patients who have

ECG from 70 year very vigrous man who had 20 thousand PVCs in 24 hours. Every third beat is a PVC (green arrow)
ECG from 70 year old very vigorous man who had 20 thousand PVCs in 24 hours. Every third beat is a PVC (green arrow PVC, blue arrow normal QRS.)This patient feels nothing with his frequent PVCs. He has had them probably lifelong and definitely for the last 10 years without any adverse consequences.

thousands of them in a 24-hour period and feel nothing. On the other hand, some of my patients suffer disabling palpitations from very infrequent PVCs. From an electrical or physiologic standpoint, there seems to be neither rhyme nor reason to why some patients are exquisitely sensitive to premature beats.

How Do I Know If My PVCs Are Benign?

My patient, Janet, is a great example of how PVCs can present and how inappropriate or inaccurate heart tests done to evaluate PVCs can lead to anxiety and unnecessary and dangerous subsequent testing.

A year ago,  Janet began experiencing a sensation of fluttering in her chest that appeared to be random. Her general practitioner noted an irregular pulse and obtained an ECG, which showed PVCS. He ordered two cardiac tests for evaluation of the palpitations: a Holter monitor and a stress echo.

A Holter monitor consists of a device the size of a cell phone connected to two sensors or electrodes that are stuck to the skin of the chest area. The electrical activity of the heart is recorded for 24 or 48 hours, and a technician then scans the entire recording looking for arrhythmias while trying to correlate any symptoms the patient recorded with arrhythmias. The Holter allows us to quantitate the PVCs and calculate the total number of PVCs occurring either singly or strung together as couplets (two  in a row), or triplets (three in a row.)

Janet’s Holter monitor showed that over 24 hours her heart beat  around 100,000 times with around 2500 PVCs during the recording.  Unfortunately, the report did not mention symptoms, so it was not possible to tell from the Holter if the PVCs were the cause of her palpitations.

A stress echocardiogram combines ultrasound imaging of the heart before and after exercise with a standard treadmill ECG. It is a very reasonable test to order in a patient with palpitations and PVCs, as it allows us to assess for any significant problems with the heart muscle, valves or blood supply and to see if any more dangerous rhythms like ventricular tachycardia occur with exercise. If it is normal, we can state with high certainty that the PVCs are benign.

Benign, in this context, means the patient is not at increased risk of stroke, heart attack, or death due to the PVCs.

In the right hands, a stress echocardiogram is superior to a stress nuclear test for these kinds of assessments for three reasons:

-Reduced rate of false positives (test is called abnormal, but the coronary arteries have no significant blockages)

-No radiation involved (which adds to costs and cancer risk)

-The echocardiogram allows assessment of the entire anatomy of the heart, thus detecting any thickening (hypertrophy), enlargement  or weakness of the heart muscle, that would mean the PVCs are potentially dangerous.

Unfortunately, my patient’s stress echo (done at another medical center) was botched and read as showing evidence for a blockage when there was none.  An invasive and potentially life-threatening procedure, a cardiac catheterization was recommended.  Similar to the situation I’ve pointed out with the performance and interpretation of echocardiograms (see here),  there is no guarantee that your stress echo will be performed or interpreted by someone who actually knows what they are doing.  So, although the stress echo in published studies or in the hands of someone who is truly expert in interpretation, has a low yield of false positives, in clinical practice the situation is not always the same.

Given that Janet was very active without any symptoms, she balked at getting the catheterization and came to me for a second opinion. I felt the stress echo was a false positive and did not feel the catheterization was warranted. We discussed alternatives, and because Janet needed more reassurance of the normality of her heart (partially because her father had died suddenly in his sixties) and thus the benignity of her palpitations/PVCs, she underwent a coronary CT angiogram instead. This noninvasive exam (which involves IV contrast administration, and is different from a coronary calcium scan), showed that her coronary arteries were totally normal.

lad-ccta
Images from Janet’s coronary CT angiogram showing the left anterior descending (LAD) coronary artery coming off the aorta. The LAD (and her other coronaries) were totally free of any plaque build-up.)

Benign PVCs-Treatment Options

Once we have demonstrated that the heart is structurally normal, reassurance is often the only treatment that is needed.  Now that the patient understands exactly what is going on with the heart and that it is common and not dangerous, they are less likely to become anxious when the PVCs come on.

PVCS can create a vicious cycle because the anxiety they provoke can cause  an increase in neurohormonal factors (catecholamines/adrenalin) that may increase heart rate , make the heart beat stronger and increase the  frequency of the PVCs.

Some patients, find their PVCs are triggered by caffeine (tea, soda, coffee, chocolate) or stress, and reducing or eliminating those triggers helps greatly. Others, like Janet, have already eliminated caffeine, and are not under significant stress.

Since I’m already over a thousand words in this post, I’ll discuss treatment options for these patients with benign PVCs who continue to have troubling symptoms after reassurance and caffeine reduction in a subsequent post.

Prematurely Yours,

-ACP

 

Shoddy Cardiovascular Screenings Are More Likely to Cause Harm Than Good

I was recently made aware, by one of my patients, of a brochure from one of the large hospital chains in the St. Louis area  that advertised “healthy heart screenings.” The website for this enterprise says the following:

Healthy Heart Screenings

In partnership with Health Fair, SSM Health Care will utilize a mobile clinic that will travel around the St. Louis area approximately 16 times per month. Screenings range from basic biometrics to cardiovascular.

Basic test package ($179) includes:
Echocardiogram Ultrasound
Stroke / Carotid Artery Ultrasound
Abdominal Aortic Aneurysm Ultrasound
Electrocardiogram (EKG)
Peripheral Arterial Disease (PAD) Test
Hardening of the Arteries Test (ASI)

Steven Nissen has discussed the dangers of these types of screenings in an article for Cardiosource.org (the online voice of the American College of Cardiology)  entitled “Screenings and Executive Physicals: Hazardous to Your Health.”

Being proactive about cardiovascular health is generally considered to be a good thing, however, these types of screenings have the potential for doing more harm than good.

First off, individuals should recognize that this service is being offered by hospital systems solely for the purpose of getting more patients into their system for further testing and procedures.

Secondly, the service is being performed by a “mobile clinic.” These types of mobile clinics typically exist to make as much money as they can. Quality control is not one of their goals. They seek high volume , rapid throughput and minimal expenses. The mobile clinic is most likely utilizing the cheapest equipment, technicians  and interpreters of these studies that they can get.

Cheap equipment and inexperienced or poorly trained technicians are more likely to yield studies which are difficult to interpret or introduce errors and artifacts. Artifacts in an imaging study are images which appear to be abnormalities but are not. The more artifacts in a study, the more inappropriate subsequent testing will most likely be performed.

One of the tests offered in this package is an ultrasound of the heart or echocardiogram. The echocardiogram is a brilliant technological development that allows us to image the structure and function of the heart. Abnormalities ranging from weakness in the pump function of the heart to leakage from the valves can very accurately be diagnosed with echocardiography when it is done right.  I have devoted a large part of my career to studying, writing about and insuring quality control in echocardiography and I have seen first hand many misdiagnoses made in the hands of the inexperienced, shoddy, greedy or unscrupulous.

Let’s consider the many ways a poorly done or interpreted echocardiogram can lead to more harm than good.

Overcalling valve problems

In addition to imaging the structure or anatomy of the heart, during an echocardiogram a technique called Doppler allows us to measure the direction, velocity and location of blood flow within the heart. Doppler, developed in the 1980s, allows us, among other things, to see if the heart valves are doing their job of allowing blood to move forward while preventing back flow. In many normal individuals, a small or trivial  amount of back flow (called regurgitation or insufficiency) can be noted. The honest, experienced cardiologist will recognize this as normal. However, if the study is performed ineptly and misread, a normal individual could be mislabeled as having a significant heart valve problem leading to unnecessary stress and anxiety and the potential for additional inappropriate and potentially dangerous testing.

This might seem like just a theoretical concern, but in the 2000s as part of a settlement with the drug company Wyeth, the maker of Fen-Phen, hundreds of thousands of patients who had taken Fen-Phen for weight loss were screened by echocardiography to look for valve problems.  Thousands of individuals with normal hearts were diagnosed with significant valvular problems after undergoing echocardiography examinations set up by the lawyers engaged in the suit. These exams were often done in hotel suites and some cardiologists made millions reading thousands of these in a short period of time. Forbes has a good summary of the scandal entitled the $22 Billion Gold Rush  here. To quote:

“Material misrepresentations” amounting to “pervasive fraud” drove 70% of the serious claims that were found payable by the Wyeth trust fund, says Joseph Kisslo, a court-appointed cardiologist who reviewed a sample of 1,000 echocardiograms in late 2004. “Thousands of people have been defrauded into believing that they have valvular heart disease when in fact they do not,” Kisslo said in a report he wrote for the trust.

I saw a number of patients who had been identified by these shoddy echocardiograms as having significant valve problems and were convinced they had serious heart problems. After I obtained and reviewed the echocardiograms I was able to reassure the patients that their hearts were normal.

Misdiagnosing the function of the heart

The echocardiogram is our premier tool for looking at how the main pumping chamber or left ventricle (LV) is working. A left ventricle that is not functioning properly leads to heart failure. The LV fills with oxygen-rich blood from the lungs when it is relaxed (diastole) and then contracts (systole) and pumps the blood out into the aorta and to the rest of the body. Precise and well-made recordings and measurements of the blood flow during diastole allow the knowledgeable cardiologist to interpret how well the heart is functioning during diastole. Similarly, recordings of the LV allow interpretation of function during systole.

Misinterpretation of both the systolic and diastolic function of the heart are common in echocardiograms that are done by inexperienced sonographers and/or cardiologists.

Misinterpretation of artifacts

Due to various technical factors (outlined in detail here), a normal heart imaged by echocardiography may appear to have an abnormality. These artifacts are more likely due to poor quality equipment and inexperienced or incompetent sonographers. The more experienced the cardiologist reading the study, the less likely that these will be interpreted as pathology.

I have encountered numerous examples of what are normal variations of the heart anatomy or artifacts read on echocardiograms as possible tumors or clots or masses within the heart. Patients invariably end up getting unnecessary testing or surgery when such misdiagnoses are made; they also experience unnecessary stress and worry.

Making Sure You Get a Good Echocardiogram

If you are undergoing an echocardiogram, whether it be for screening which I (and the American Heart Association and the American College of Cardiology) do not recommend or for an appropriate indication (see here for appropriate indications), then it is in your best interest for you to make sure that the test is done and interpreted optimally.

Ideally, your test is being done by a sonographer who has undergone a recognized training program and is credentialed as a Registered Diagnostic Cardiac Sonographer (RDCS by the American Registry of Diagnostic Sonographers) or a Registered Cardiac Sonographer (RCS by the Cardiovascular Credentialing International).

Your echocardiogram should be done in a facility which has been certified by the Intersociety Accreditation Committee for Echocardiography (ICAEL). This will insure that the equipment, personnel , reports and interpretations are meeting minimal standards and that there is in place an ongoing program of quality assessment.

Your echocardiogram should be interpreted by a cardiologist who has undergone appropriate training in echocardiography and is staying up to date with the latest technology and information in the area. ICAEL certification of the lab will verify this to some extent. Even better, is a cardiologist who is Board Certified in Echocardiography.

In summary, don’t pay for an echocardiogram done by a mobile lab as part of a cardiovascular screening program no matter where it is performed or who is promoting it.  Although you may think you are being proactive about your health, chances are you will be more harmed than helped by the outcome.

 

Should You Get a Routine Annual Electrocardiogram (ECG)?

Recently, the skeptical cardiologist  was asked by his  old friend and life coach (OFALCSC) whether he was correct to refuse the annual electrocardiogram (ECG) which his primary care doctor had recommended during an annual physical.

ECG showing atrial fibrillation
ECG showing atrial fibrillation

Most of my patients feel that the ECG has the ability to tell me  quite a bit about their heart. The technique utilizes electrodes on the arms, legs and chest region which  record with precision, the depolarization and repolarization of the upper chambers (atria) and lower chamber (ventricles) of the heart.

The ECG is THE tool for assessing the rhythm of the heart.  If performed and interpreted properly (not always a given) it tells us very precisely whether we are in normal (sinus) rhythm, wherein the atria contract synchronously before the ventricles contract, or in an abnormal rhythm. It is also very good at telling us whether you are having a heart attack.

If you are, however, like the OFALSC, and feel fine (meaning without symptoms or asymptomatic), exercise regularly, have never had heart problems,  and have a pulse between 60 and 90, the value of the routine annual ECG is very questionable. In fact, the United States Preventive Services Task Force (USPFTF)

“recommends against screening with resting or exercise electrocardiography (ECG) for the prediction of coronary heart disease (CHD) events in asymptomatic adults at low risk for CHD events”

(for asymptomatic adults at intermediate or high risk for CHD they deem the evidence insufficient). The USPSTF feels that that the evidence only supports an annual BP screen along with measurement of weight and a PAP smear.

To many, this seems counter-intuitive: how can a totally benign test that has the potential to detect early heart disease or abnormal rhythms not be beneficial?

There is a growing movement calling for restraint and careful analysis of the value of all testing that is done in medicine. Screening tests, in particular are coming under scrutiny.
Even the annual mammogram, considered by most to be an essential tool in the fight against breast cancer, is now being questioned.

My former cardiology partner, Dr. John Mandrola, who writes the excellent blog at http://www.drjohnm.org, has started an excellent discussion of a recent paper that shows no reduction of mortality with the annual mammogram. He looks at the topic in the context of patient/doctor perception that “doing something” is always better than doing nothing, and the problem of “over-testing.”

In my field of cardiology there is much testing done. It ranges from the (seemingly) benign and (relatively) inexpensive electrocardiogram to the invasive and potentially deadly cardiac catheterization. For the most part, if patients don’t have to pay too much, they won’t question the indication for the tests we cardiologists order. After all, they want to do as much as possible to prevent themselves  from dropping dead from a heart attack and they reason that the more testing that is done, the better, in that regard.

The Problem of False Positives and False Negatives

But all testing has the potential for negative consequences because of the problem of false positives and negatives. To give just one example: ECGs in people with totally normal hearts are regularly interpreted as showing a prior heart attack. This is a false positive. The test is positive (abnormal) but the person does not have the disease. At this point, more testing is likely to be ordered; specifically, a stress test. Stress tests in low risk, asymptomatic individuals often result in false positive results. After a false positive stress test, it is highly likely that a catheterization will be ordered. This test carries potential risks of kidney failure, heart attack, stroke and death. It is bad enough that the cascade of testing initiated by an abnormal, false positive,  screening test results in unnecessary radiation, expense and bother but  in some cases it end up killing patients rather than saving lives.

On the other end of the spectrum is the false negative ECG. Most of my patients believe that if their ECG is normal then their heart is OK. Unfortunately the ECG is very insensitive to cardiac problems that are not related to the rhythm of the heart or an acute heart attack.

Patients who have 90% blockage of all 3 of their major coronary arteries and are at high risk for heart attack often have a totally normal ECG. This is a false negative. The patient has the disease (coronary artery disease), but the test is normal. In this situation the patient may be falsely reassured that everything is fine with their heart. The next day when they start experiencing chest pain from an acute heart attack, they may dismiss it as heart burn instead of going to the ER.

More and more, screening tests like the ECG and the mammogram  are rightfully being questioned by patients and payers. For a more extensive discussion about which tests in medicine are appropriate check out the American Board of Internal Medicine’s http://www.choosingwisely.org.

Keep in mind: not uncommonly,  doing more testing can result in worse outcomes than doing less.