Apple claims that its Apple Watch can detect atrial fibrillation (AF) and appropriately notify the wearer when it suspects AF.
This claim comes with many caveats on their website:
Apparently it needs to record 5 instances of irregular heart beat characteristic of atrial fibrillation over at least 65 minutes before making the notification.
This feature utilizes the watch’s optical heart sensors, is available in Apple Watch Series 1 or later and has nothing to do with the Apple Watch 4 ECG recording capability which I described in detail in my prior post.
Failure To Detect AF
A patient of mine with known persistent AF informed me yesterday that she had gone into AF and remained in it for nearly 3 hours with heart rates over 100 beats per minute and had received no notification. She confirmed the atrial fibrillation with both AW4 recordings and AliveCor Kardia recordings while she was in it.
The watch faithfully recorded sustained heart rates up to 140 BPM but never alerted her of this even though the rate was consistently over her high heart rate trigger of 100 BPM.
The patient had set up the watch appropriately to receive notifications of an irregular rhythm.
Reviewing her tracings from both the AW4 and the Kardia this was easily diagnosed AF with a rapid ventricular response.
What does Apple tell us about the accuracy of the Apple Watch AF notification algorithm? All we know is the unpublished , non peer-reviewed data they themselves collected and presented to the FDA.
In a study of 226 participants aged 22 years or older who had received an AFib notification while wearing Apple Watch and subsequently wore an electrocardiogram (ECG) patch for approximately 1 week, 41.6% (94/226) had AFib detected by ECG patch. During concurrent wear of Apple Watch and an ECG patch, 57/226 participants received an AFib notification. Of those, 78.9% (45/57) showed concordant AFib on the ECG patch and 98.2 % (56/57) showed AFib and other clinically relevant arrhythmias. These results demonstrate that, while in the majority of cases the notification will accurately represent the presence of AFib, in some instances, a notification may indicate the presence of an arrhythmia other than AFib. No serious device adverse effects were observed
This tells us that about 80% of notifications are likely to be Afib whereas 20% will not be Afib. It is unclear what the “other clinically relevant arrhythmias” might be. If I had to guess I would suspect PVCS or PACS which are usually benign.
If 20% of the estimated 10 million Apple Watch wearers are getting false positive notifications of afib that means 2 million calls to doctor or visits to ERs that are not justified. This could be a huge waste of resources.
Thus the specificity of the AF notification is 80%. The other important parameter is the sensivitiy. Of the cases of AF that last >65 minutes how many are detected by the app?
Apple doesn’t seem to have any data on that but this obvious case of rapid AF lasting for 3 hours does not give me much confidence in their AF detection algorithms.
They do have a lot of CYA statements indicating you should not rely on this for detection of AF:
It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present; rather the feature is intended to opportunistically surface a notification of possible AFib when sufficient data are available for analysis. These data are only captured when the user is still. Along with the user’s risk factors, the feature can be used to supplement the decision for AFib screening. The feature is not intended to replace traditional methods of diagnosis or treatment.
My patient took her iPhone and Apple Watch into her local Apple store to find out why her AF was not detected. She was told by an Apple employee that the Watch does not detect AF but will only notify her if her heart rate is extremely low or high. I had asked her to record what they told her about the problem.
As I’ve written previously (see here) the Apple Watch comes with excessive hype and minimal proof of its accuracy. I’m sure we are going to hear lots of stories about AF being detected by the Watch but we need some published, peer-reviewed data and we need to be very circumspect before embracing it as a reliable AF monitor.
As I described here, the Kardia Band (KB) is an FDA-approved Apple Watch accessory available to the general public without a prescription which records a high quality single-lead ECG.
I’ve been using mine now for a while and can confirm the ease and accuracy of the ECG recordings it makes. I find recordings made with my Apple Watch/Kardia Band are reliably high quality with minimal artifact (unless I’m running on a treadmill.)
Once the 30 second recording is completed, the Kardia app on the Apple Watch takes about 5 seconds to process the information using an AI algorithm and then makes a determination of normal sinus rhythm (NSR), atrial fibrillation or unclassified.
In the JACC study, investigators from the Cleveland Clinic studied 100 consecutive patients presenting for cardioversion from AF with recordings made before and after the procedure. KB interpretations were compared to 12 lead ECGS read by electrophysiologists.
KB interpretations identified AF with 93% sensitivity and 84% specificity. Of the total 169 recordings, 34% were unclassified due to short recordings, low-amplitude p waves, and baseline artifacts.
The authors concluded that the KB algorithm for AF detection, when it is supported by a physician review can reliably differentiate AF from NSR.
(Of note the lead author on this study is on the advisory board of Alivecor the maker of the KB and AliveCor (AliveCor, Mountain View, CA) provided the Kardia Band monitors which were connected to an Apple Watch and paired via Bluetooth to a smartphone device for utilization in the study. AliveCor was not involved in the design, implementation, data analysis, or manuscript preparation of the study.)
My Updated Kardia Experience
I have found the standard Kardia device to be immensely helpful in the management of my afib patients before and after cardioversions (see my prior description here). The paper mentions that 8% of these pre-cardioversion patients showed up for the procedure in normal sinus rhythm, noting that
For each of these patients, the automated KB algorithm did not erroneously identify AF, and the physician interpretation of the KB recording correctly confirmed SR in each case.
Needless to say, it is better to find out a cardioversion is not needed before the patient shows up for the procedure. I would estimate this happens about 5-10% of the time in my practice.
The Kardia device or the KB is also really helpful post cardioversion. If the patient makes daily recordings (which I can review on Kardia Pro online) h/she and I know exactly how long sinus rhythm persisted before reverting back to AF.
This is important information which impacts future management decisions.
Kardia Band Versus Standard Kardia Device
None of my patients have purchased the Kardia Band most likely due to the cost and the fact that they don’t have an Apple Watch. If you have an Apple Watch and want to monitor your heart rhythm I think the KB is a good choice. Otherwise, the original AliveCor mobile ECG device continues to do a fantastic job (in conjunction with Kardia Pro, see here).
The combination of Kardia and Kardia Pro has substantially reduced my use of expensive and annoying long term monitors in my AF population.
In my next update on the KB I will share a reader’s real world description of the pros and cons of the KB (with Smart Rhythm monitoring) in a patient post cardioversion for AF.
The skeptical cardiologist has been evaluating the Kardia Band from AliveCor which allows one to record single lead medical grade ECGS on your Apple Watch. What follows is my initial experience with setting up the device and using it to make recordings.
After ordering my Kardia Band for Apple Watch on 11/30 from AliveCor the device appeared on my door step 2 days later on a Saturday giving me most of a Sunday to evaluate it.
What’s In The Box
Inside the box I found one small and one large black rubber wrist watch band
The larger one had had a small squarish silver metallic sensor and the smaller one had a space to insert a sensor. It turns out my wrist required the smaller band and it was very easy to pop out the sensor and pop it into the smaller band.
After replacing my current band with the Kardia band (requires pushing the button just below the band and sliding the old band out then sliding the new one in) I was ready to go.
The Eternal fiancée did not complain about the appearance of the band so I’m taking that to mean it passes the sufficiently stylish test. She did inquire as to different colors but it appears AliveCor only has one style and one color to choose from right now.
I have had problems with rashes developing with Apple’s rubbery band and switched to a different one but thus far the Kardia band is not causing wrist irritation.
I didn’t encounter any directions in the box or online so I clicked on the Kardia app on the watch and the following distressing message appeared.
Prior to 11/30 Kardia Band only worked in certain countries in Europe so I suspected my AliveCor app needed to be updated.
I redownloaded the Kardia app from the Apple App Store , deleted it off my Watch and reinstalled it.
I was thrilled when the app opened up and gave me the following message
However, I was a little puzzled as I was not aware that setting up Smart Rhythm was a requirement to utilize the ECG recording aspect of Kardia Band. Since I have been granted a grandfathered Premium membership by AliveCor I knew that I would have access to Smart Rhythm and went through the process of entering my name and email into the Kardia app to get this started.
Alas, when the Watch Kardia app was accessed after this I continued to get the same screen. Clicking on “need help” revealed the following message:
Bluetooth was clearly on and several attempts to restart both the watch and the iPhone app did not advance the situation.
I sent out pleas for assistance to AliveCor.
At this point the Eternal Fiancee had awoken and we went to Sardella for a delightful brunch . I had this marvelous item:
Later on that day I returned to my Kardia Band iPhone and deinstalled, reinstalled , reloaded and restarted everything.
The First Recording
At this point it worked and I was able to obtain my first recording by pushing the record ECG button and holding my thumb on the sensor for 30 seconds.
I’ve made lots of recordings since then and they are good quality and have accurately recognized that I am in normal sinus rhythm.
The Smart Rhythm component has also been working. Here is a screen shot of today’s graph.
You’l notice that the Smart Rhythm AI gave me a warning sometime in the morning (which I missed) as it felt my rhythm was abnormal. I missed making the recording but am certain that I was not in afib.
Comparison of the Kardia Band recording (on the right) versus the separate Kardia device recording (on left) shows that they are very similar in terms of the voltage or height of the p waves, QRS complexes and T waves.
I felt a palpitation earlier and was able to quickly activate the Kardia Watch app and make a recording which revealed a PVC.
In summary, after some difficulty getting the app to work I am very pleased with the ease of recording, the quality of the recording and the overall performance of Kardia Band. The difficulties I encountered might reflect an early adoption issue which may already be resolved. Please give me feedback on how the device set up worked for you.
I’ll be testing this out on patients with atrial fibrillation and report on how it works in various situations in future posts.
After more experience with the Smart Rhythm monitoring system which I think could be a fantastic breakthrough in personal health monitoring I’ll give a detailed analysis of that feature.
AliveCor has finally gotten approval from the FDA to release its Kardia Band in the United States.
The skeptical cardiologist is quite excited to get his hands (or wrist) on one and just gave AliveCor $199 to get it.
The device incorporates a mobile ECG sensor into a wrist band that works with either 42 or 38 mm Apple watches. I’ve written extensively about AliveCor’s previous mobile ECG product (here and here) which does a good job of recording a single lead ECG rhythm strip and identifying atrial fibrillation versus normal rhythm,
Hopefully, the Kardia Band will work as well as the earlier device in accurately detecting atrial fibrillation.
According to this brief video to make a recording you tap the watch screen then put your thumb on the sensor on the band.
The app can monitor your heart rate constantly and alerts you to make a recording if it thinks you have an abnormal rhythm.
I was alerted to the release of Kardia by Larry Husten’s excellent Cardio Brief blog and in his post he indicates that the alert service , termed Smart Rhythm, requires a subscription of $99 per year.:
AliveCor simultaneously announced the introduction of SmartRhythm, a program for the Apple Watch that monitors the watch’s heart rate and activity sensors and provides real-time alerts to users to capture an ECG with the Kardia Band. The program, according to an AliveCor spokesperson, “leverages sophisticated artificial intelligence to detect when a user’s heart rate and physical activity are out of sync, and prompts users to take an EKG in case it’s signaling possible abnormalities like AFib.”
The Kardia Band will sell for $199. This includes the ability to record unlimited ECGs and to email the readings to anyone. The SmartRhythm program will be part of the company’s KardiaGuard membership, which costs $99 a year. KardiaGuard stores ECG recordings in the cloud and provides monthly summary reports on ECGs and other readings taken.
AliveCor tells me my Kardia Band will be shipped in 1-2 days and I hope to be able to give my evaluation of it before Christmas.
Please note that I paid for the device myself in order to avoid any bias that could be introduced by receiving largesse from AliveCor.
N.B. Larry Husten’s article includes some perspective and warnings from two cardiologist and can be read here.
Another article on the Kardia Band release suggests that the Smart Rhythm program at $99/ year is a requirement.
Perhaps, AliveCor’s David Albert can weigh in on whether the annual subscription is a requirement for making recordings or just allows the continuous monitoring aspect.
The skeptical cardiologist stopped wearing his initial wearable piece of technology (a Garmin device that constantly prompted him to move, described here), within 6 months of purchasing it; it just wasn’t worth the effort of charging and putting on the the wrist.
I am not alone in finding FitBit type devices not worth wearing after awhile. ConscienHealth points out that sales and stock price of FitBit are down significantly. Part of this is competition, part saturation of the market, but part must be due to individuals going through a process similar to mine.
The great promise that wearable fitness/sleep/activity tracking devices would make us healthier has not been fulfilled.
A recent study showed that among obese young adults, the addition of a wearable technology device to a standard behavioral intervention resulted in less weight loss over 24 months.
Taking the Apple Watch Plunge
However, knowing I was a fan of all things Apple, the eternal fiancee bought me a Series 1 Apple Watch, which I have come to love. This love has little to do with how the device tracks my steps or my sleep or my pulse or my movement.
Let me count the ways I do love my Apple Watch…
I can answer my phone without touching my phone or
having it near me or even knowing where my phone is.
Since I’m constantly misplacing the damn thing, this is a surprisingly helpful feature. There is also the really cool aspect of walking around and having a telephone conversation using my watch.
During a busy day of seeing patients in the office I typically will receive multiple calls from the ER or other doctors I have to talk to immediately. Now, I can rapidly screen my calls with a tilt of my wrist and excuse myself to take the call. If I’ve been trying to get ahold of Dr. X to discuss a mutual patient, and he calls while I’m doing a transesophageal echocardiogram, I can have someone touch my watch instead of reaching into my pants for my iPhone, or searching in my office for it, or missing the call altogether.
I’m missing much less important calls these days.
And although previously I would take calls while driving, the watch makes this process much simpler and therefore much safer.
2. Receiving and responding to text messages does not require accessing my iPhone.
This doesn’t seem like that big of a deal, but again, the ability to rapidly scan incoming texts with just a tilt of the wrist greatly facilitates expeditious screening and processing.
The Apple Watch allows response via either audio recording (translated seamlessly and quickly to text) or pre-set standard responses or emojis.
3. “Hey Siri” function simplifies and makes hands-free and iPhone-free many useful tasks. For example:
To set a timer for my (heart-healthy) boiled eggs, I say “Hey Siri, set timer for 11 minutes.” Normally in this situation I avoid setting the timer because I’m too busy to grab my phone, open it, and find the timer app (I know I could use Siri on my phone, but that requires more effort).
If I suddenly remember I need to call someone while driving, the “Hey Siri” function allows making the call without taking my hands off the steering wheel.
If a brilliant idea for a blog post occurs to me while driving or walking through the hospital corridors, “Hey Siri” can take a note with ease.
4. Checking the time is a lot easier (I know, all watches do this, but I’ve haven’t worn a watch for about 20 years).
5. If I misplace my iPhone (this happens roughly once per hour when I am at home), I can “ping” it by pushing a button on my Apple Watch: follow the ping and “voila!” I have found my iPhone. Most of the time it is lying under a piece of paper or article of clothing within a few feet of where I’m working, but sometimes it is in an obscure corner for obscure reasons.
Here’s a true story which illustrates my tremendous absent-mindeness and the value of the “ping.”
I left my office Friday evening and after stepping outside I realized I did not have my iPhone in its usual location, the left front pocket of my pants. I searched the pockets in my pants and in the jacket I was wearing to no avail. I began heading back to my office believing that I had left it on my desk but then realized that I might have put it in my satchel. Not in my satchel. A bright idea then occurred to me: ping the iPhone to see if it was in the satchel, but hidden.
Sure enough I heard the iPhone ping. But it was not in the satchel; it was (for obscure reasons) in my shirt pocket (a place that apparently makes it undetectable to me).
6. Information on local weather is immediately available. I have configured my watch “dial” to show me the local temperature. Right now with a flick of my wrist I can see that it’s 17 degrees outside and I’m going to have to dress warmly. I’ve also configured my watch dial to tell me when sunrise/sunset is and what my heart rate is.
These last two things, although immensely interesting, are not that helpful.
Oh, excuse me, my watch timer is telling me my eggs are done.
P.S. I’m still in the process of evaluating the work-out/sleep/move/mindfulness features of Apple Watch and hope to write about it in the near future.
Feel free to share the things you love or hate about your Apple Watch below.
In a previous post, the skeptical cardiologist pontificated on the causes and evaluation of the most common cause of palpitations: premature ventricular contractions or PVCs.
The vast majority of these common extra beats turn out to be benign (meaning not causing death, heart attack or stroke), and most patients with sufficient reassurance of this benignity (often accompanied by significant caffeine reduction), do well. These people usually continue to notice the beats either randomly, or with stress, but they recognize exactly what is going on and are able to say to themselves “there go my benign PVCs again,” and aren’t worried or bothered.
A small percentage of patients that I diagnose with palpitations due to benign PVCs continue to have symptoms.
Part of my initial evaluation involves checking potassium, magnesium, kidney function, and thyroid levels.
Potassium Supplementation For PVCs
Low potassium levels (hypookalemia) have been clearly associated with an increase in ventricular ectopy. Patients who take diuretics like hydrochlorothiazide (HCTZ, often used for high blood pressure) or furosemide (Lasix, often used for leg swelling or heart failure), are at high risk for hypokalemia with potassium levels less than 3.5 meQ/L.
Hypokalemia can also develop if you are vomiting, having diarrhea, or sweating excessively. There are lots of other infrequent causes including excess licorice consumption. The body regulates potassium levels closely, due to its importance in the electrical activities involved in cardiac, muscular and neurological function.
The normal range of potassium (K) is considered to be 3.5 to 5 meq/L , however, I have found that PVCs are more frequent when the potassium is less than 4.
Most of my symptomatic PVC patients with potassium less than 4 find significant improvement with potassium supplementation. I usually give them a prescription for potassium chloride (KCl) 10-20 meq daily to accomplish raising the level to >4.
An alternative to potassium supplements is ramping up how much potassium you consume in your diet. Most patients I talk to about low K immediately assume they should eat more bananas, but lots of fresh fruit and vegetables contain as much or more K than bananas.
The charts to the right show that a medium tomato contains as much K as a medium banana with a third of the calories. Avocados are a great source of K and contain lots of healthy fat. Yogurt (and I recommend full fat yogurt, of course) is a great source as well.
If you have kidney disease you are much more likely to develop hyperkalemia, or high K, and you want to avoid these high K foods. Potassium infusions are used as part of a “lethal injection” in executions because extreme hyperkalemia causes the heart to stop beating. (In fact, Arkansas is hurrying to execute 8 men between April 17 and 27 utilizing KCl. According to deathpenaltyinformation.org: “The hurried schedule appears to be an attempt to use the state’s current supply of eight doses of midazolam, which will expire at the end of April. Arkansas does not currently have a supply of potassium chloride, the killing drug specified in its execution protocol, but believes it can obtain supplies of that drug prior to the scheduled execution dates”)
Lifestyle, Stress and PVCs
It’s probably time I revealed that I have PVCs. I feel them as a sense that something has shifted inside my chest briefly, like my breath has been interrupted, like my heart has hiccoughed. If I didn’t know about PVCs and hadn’t made the diagnosis very quickly by hooking myself up to an ECG monitor in my office, I know I would have become very anxious about it.
I know exactly what causes them: stress and anxiety. And this is the case for many patients. Stress activates our sympathetic nervous system, causing the release of hormones from the adrenal gland that prepare us for “fight or flight.” These hormones stimulate the heart to beat faster and harder and often trigger PVCs.
I rarely get PVCs these days, as the major source of stress in my personal life has gone away. This is also a typical story my patient’s relate: troubling palpitations seem to melt away when they retire or change to less stressful occupations, or as they recover from depression/anxiety/grief related to death of loved ones, divorce or illness.
You can’t always control external stresses, but several factors in your lifestyle are key to managing how those stresses activate your sympathetic nervous system and trigger troubling PVCs.
Dr. Mandrola lists as Steps 5-8 (Steps 1-4 are reassurance) for PVC treatment his “four legs of the table of health”:
: good food, good exercise, good sleep and good attitude. Cutting back on caffeine and alcohol, looking critically at the dose of exercise, going to bed on time, and smiling are all great strategies for PVCs.
Of these four table legs, I consider regular aerobic exercise the most important, and modifiable factor for PVC reduction. Aerobic exercise improves mood and increases the parasympathetic (the calming component of the autonomic nervous system) activity, while lowering the output of the sympathetic nervous system.
The three factors that I find essential to handling the demanding and stressful job of being a cardiologist: restful sleep, regular, aerobic exercise and lots of love from my eternal fiancee (who also has occasional PVCs!)
Beyond sleep and exercise there is a plethora of techniques that purport to help individuals deal with stress: yoga, meditation, and progressive muscular relaxation, among them.
Apps touting methods for relaxation abound these days. My new Apple Watch is constantly advising me to engage in a breathing exercise for a minute at a time. I don’t find any of these techniques helpful for me (I haven’t found a good way to shut my brain down without falling asleep), but they may work for you.
Magnesium, Snake Oil and PVCs
Patients will find that the internet is rife with stories of how this supplement or vitamin or herb dramatically cures PVCs. You can be assured that a sales pitch accompanies these claims and that the snake oil being promoted has not been proven effective or safe. Because symptomatic PVCs like most benign, common and troubling conditions (lower back pain, fatigue, and nonspecific GI troubles come to mind), are closely related to mood and wax and wain spontaneously; the placebo effect proves powerful. In such conditions, snake oil and charlatans thrive.
Magnesium is enthusiastically hyped on the internet for all manner of cardiovascular problems including PVCs. Even Dr. Mandrola, who I respect quite a lot as an EP doc who promotes lifestyle change and who is definitely not a quack, lists his step 10 for PVCs (apologetically) as follows:
Step 10 (a): Please don’t beat me up on this one. Some patients report benefit from magnesium supplementation. I have found it helpful in my case of atrial premature beats. Let me repeat, I am not promoting supplements. Healthy patients with benign arrhythmia might try taking magnesium, especially at night. Don’t take magnesium if you have kidney disease. And if you take too much, watch out for diarrhea.
Most of the internet’s top quacks, however, greedily market and glowingly swear by magnesium. A Google search for magnesium cardiovascular disease yields 833,000 entries and the first page is a Who’s Who of quackery, including Dr Mercola (strong candidate for America’s greatest quack), Dr. Sinatra (see here, currently in the semifinals for America’s greatest quack cardiologist), NaturalNews and Life Extension (see here). This totally unsupported and dangerous blather from the Weston Price Foundation is often repeated and is typical:
(magnesium) Deficiency is related to atherosclerosis, hypertension, strokes and heart attacks. Deficiency symptoms include insomnia, muscle cramps, kidney stones, osteoporosis, fear, anxiety, and confusion. Low magnesium levels are found in more than 25 percent of people with diabetes. But magnesium shines brightest in cardiovascular health. It alone can fulfill the role of many common cardiac medications: magnesium inhibits blood clots (like aspirin), thins the blood (like Coumadin), blocks calcium uptake (like calcium channel-blocking durgs such as Procardia) and relaxes blood vessels (like ACE inhibitors such as Vasotec) (Pelton, 2001).
Magnesium levels are very important to monitor in hospitalized and critically ill patients, especially those receiving diuretics and medications that can effect cardiac electrical activity.
However, for individuals with normal diets and palpitations due to PVCs, there is scant evidence that it plays a significant role in cardiovascular health.
The MAGICA study looked at supplementation with both magnesium and potassium (in the active treatment group, daily oral dosing consisted of 2 mg of magnesium-dl-hydrogenaspartate (6 mmol magnesium) and 2 mg of potassium-dl-hydrogenaspartate (12 mmol potassium) daily. The dose was chosen to increase the recommended minimal daily dietary intake of magnesium (12 to 15 mmol) and potassium (20 to 30 mmol) by ∼50% in addition to usual diet ) in 307 patients with more than 720 PVCs per hour and normal baseline K and Mg levels.
The patients receiving magnesium/potassium supplements showed a decrease of 17% in frequency of PVCs but no improvement in symptoms.
A 2012 study in a Brazilian journal evaluated magnesium pidolate (MgP) in 60 patients with both PVCs and premature atrial contractions (PACs). The dose of MgP was 3.0 g/day for 30 days, equivalent to 260 mg of Mg elemental.
93% of patients receiving MgP experienced improved symptoms compared to only 13% of patients recieiving placebo. Both PVC and PAC frequency was reduced in those receiving MGP, whereas they increased by 50% in those receiving placebo.
This small study has never been reproduced, and the main results table makes little sense. It would not have been published in a reputable American cardiology journal and cannot be relied on to support magnesium for most patients with benign PVCs or PACs.
Drug or Ablation Treatment of PVCs: Usually Not Needed
A small percentage of my patients require treatment with beta-blockers which reduces the effects of the sympathetic nervous system on the heart. Very rarely, I will use anti-arrhythmic drugs. And every once in a while, very frequent PVCs resulting in cardiomyopathy require an ablation.
However, the vast majority of patients with benign PVCs, in my experience, feel drastically better with a simple non-pharmacological approach consisting of 4 factors:
Reassurance that the PVCS are benign
Caffeine (or other stimulant) reduction
Lifestyle adjustment with regular aerobic exercise