Tag Archives: cardioversion

Why I Favor The Early Restoration and Maintenance of Sinus Rhythm In Most Patients With Atrial Fibrillation

When your heart stops beating synchronously and goes into atrial fibrillation all sorts of bad things begin happening. The normal mechanisms for controlling how fast your heart is beating are lost and in most individuals the rate accelerates inappropriately. The strength of the atria’s pumping force and the normal precise synchronization of the upper and lower chambers  deteriorates.

You might logically conclude then, that all efforts should be focused on converting the rhythm back to normal,  for in the normal rhythm the heart can go back to beating regularly, efficiently  and synchronously the way nature intended.

Maintenance of this normal (sinus) rhythm (NSR), presumably, will eliminate the high risk of clot formation and stroke associated with atrial fibrillation (AF) , prevent heart failure, and prolong life.

AF is abnormal. the thinking goes, and normality is the state in which we were born and to which we should seek to return.

Is Normal Sinus Rhythm Superior to Atrial Fibrillation?

It would be hard to find a cardiologist who doesn’t believe that patients are better off in NSR than AF but the more difficult question and more clinically relevant question is “if your heart has gone into atrial fibrillation will you do better in the long run with a strategy of trying to convert the rhythm back to normal and keep it there (which involves medications (anti-arrhythmic drugs) and/or procedures) versus just controlling the heart rate and letting the atria fibrillate to their heart’s content.

Unfortunately, studies that have compared the  strategy of maintaining NSR (rhythm control) with leaving the heart to fibrillate have not shown a benefit in preventing stroke or death in the patients randomized to rhythm control

To quote the 2016 European Society of Cardiology  guidelines on AF

Although many clinicians believe that maintaining sinus rhythm can improve outcomes in AF patients, all trials that have compared rhythm control and rate control to rate control alone (with appropriate anticoagulation) have resulted in neutral outcomes.

(see references for this below)

However, findings from these studies can only be applied to the population studied, thus younger patients without structural heart disease and patients over age 80, who combined constitute up to 50% of the AF group were not represented in these comparison studies.

The elderly are more dependent on normal atrial function for maintenance of cardiac output and are more likely to have issues with anticoagulation, thus they may benefit more from maintenance of NSR than the young.

In addition, much of the morbidity and mortality in these trials was related to failure to anticoagulate patients who were in NSR. The stroke risk persists in this group, we have learned, because they may not recognize when AF occurs. Therefore, most authorities recommend lifelong  anticoagulation for those who have had  AF and have significant risk factors for stroke whether they

These and other  reasons for the  failure of the so-called rhythm strategy have long been debated but most experts blame it on the absence of a safe and effective method for maintaining NSR: the drugs  and procedures (catheter ablations) we have used create their own problems and don’t always work.

Why Then, Do I And Most Cardiologists Recommend Efforts To Maintain Normal Sinus Rhythm?

This is a question almost no AF patients ask. It is quite easy for a treating cardiologist to invoke the “normality” of NSR and the dangers of AF and most AF patients require no more justification. But they really should demand a compelling rationale.

For those who feel badly in AF despite treatment with medications to keep the heart rate normal cardiologists can justify the efforts because we are making patients feel better

The ESC guideline summarizes this as follows

For now, rhythm control therapy is indicated to improve symptoms in AF patients who remain symptomatic on adequate rate control therapy.

However, there are important limitations to letting symptoms guide our approach.

For one, symptoms are in the mind of the patient and cannot be measured objectively. For another, the symptoms a patient experience could be from something other than AF.

You might think that we can objectively verify that symptoms are due to atrial fibrillation if they resolve after converting the patient to sinus rhythm but symptoms can be heavily influenced by the patient’s perception that something has been done to fix them. This placebo effect is well-known from clinical trials of medications but may be even more prominent after procedures.

It is not uncommon for me to perform a cardioversion on a patient , see the patient in follow-up in AF and have them tell me how tremendous they have felt since the cardioversion.

The difficulty of objective symptom measurement is one of many factors contributing to  a tremendous variability in how cardiologists approach rhythm control  for AF.

Some cardiologists have concluded that maintaining SR is rarely worth the trouble and they add rate controlling medications and anticoagulants and see the patient back once a year. Let’s call these NSR Nihilists

On the other end of the spectrum, cardiologists who are true believers in the value of NSR run their patients through multiple anti-arrhythmic drugs, cardioversions and ablations to achieve that goal. When this is done excessively such cardiologists become NSR Overtreaters.

I put myself somewhere in between the Nihilists and the Overtreaters and consider myself a rational NSR advocate or enthusiast but one who has a very clear understanding of the dangers of over treatment and who recognizes that many patients have done well for decades in permanent AF.

Recording and observation of symptoms depends heavily  on the recorder and observer: the Nihilists are loath to find symptoms attributable to AF whereas the Overtreater may see any and all symptoms as due to AF.

Like other areas in life and medicine we have to look closely at hidden motivations and conflicts of interest to fully understand variations in behavior.

If one were to analyze the financial benefit from testing and procedures to treating cardiologists I have no doubt that the Overtreaters are getting a lot more than the Nihilists.

In an ideal world, cardiologists would not benefit more financially based on what procedures they recommend be performed on their patients but this is not the reality.

Reasons For NSR Maintenance Beyond Symptoms

 I’ve mentioned two solid reasons for aggressively trying to maintain NSR in a previous post:

A second group of patients, I think, benefits the most from maintaining sinus rhythm (rhythm control strategy): patients who develop heart failure when they go into AF.

These patients may not even know they are in AF because they don’t feel the typical symptoms initially.  After a few days or weeks or months of being in afib silently, however, they develop shortness of breath, weakness and leg  swelling – classic signs of heart failure.

When we look at the heart of such a patient by echocardiography, we often find one of two things causing the heart failure: a weakening of the heart muscle (cardiomyopathy) or significant leakage/backflow from the mitral valve (mitral regurgitation). Following cardioversion and maintenance of SR for weeks to months, the heart muscle strengthens back to normal and/or the mitral regurgitation improves dramatically and the heart failure resolves.

The 2014 ACC guidelines for management of AF admit the lack of randomized trials supporting maintenance of NSR but cite several factors that would “favor attempts at rhythm control” with which I generally agree. These are:

  • difficulty in achieving adequate rate control,
  • younger patient age,
  • tachycardia-mediated cardiomyopathy,
  • first episode of AF,
  • AF precipitated by an acute illness
  • patient preference.

If, after discussion of the options, a patient decides they prefer no attempts at maintaining NSR,  I try to make them aware that AF begets AF. The longer they stay in AF the larger and more diseased their atria become and the harder it is to stay in NSR with any techniques. In other words, this not a decision that can easily be reversed a few years from now if they start feeling poorly.

The ACC guidelines put it this way:

AF progresses from paroxysmal to persistent in many patients and subsequently results in electrical and structural remodeling that becomes irreversible with time . For this reason, acceptance of AF as permanent in a patient may render future rhythm-control therapies less effective. This may be more relevant for a younger patient who wishes to remain a candidate for future developments in rhythm-control therapies. Early intervention with a rhythm-control strategy to prevent progression of AF may be beneficial.

Many of the factors cited for leaning toward NSR maintenance are, of course, soft and vague.  One doctor’s young patient is another doctor’s old patient. The definition of adequate rate control is unclear. What qualifies as an acute illness?

My Approach to Maintenance of NSR

I favor a more aggressive approach to maintenance of NSR. I justify this because in my experience with meticulous attention to detail and with close monitoring of patients on anti-arrhythmic drugs I have observed that most patients do better in the long run with NSR Than AF.

Over thirty years of managing patients with AF and comparing those who are left to permanently be in AF versus those who maintain NSR  I see substantial differences. Let me cite two case examples to buttress my argument.

A 75-year-old man with permanent atrial fibrillation came under my care after his cardiologist retired. He had been in AF with rate well controlled and on anticoagulation since 2008. He is active without any symptoms.

He had an echocardiogram in 2008 with the new onset of AF and it showed a normal sized left and right atria and no valvular problems.

Over 10 years,  however, the size of both his atria have dramatically increased. His current echo shows severe enlargement of his left atrium (LA volume index=72 cm3/M2) and right atrium (RA area=26 cm2). He has developed significant leakage (regurgitation)  from both his mitral and tricuspid valves.

afmrlae

This is the norm for most patients who have been in AF for a long time.

The larger the left atrium gets over time, the more dysfunctional it becomes and the more likely clots are to form in the LA appendage. Although anticoagulation dramatically reduces the formation of LA clots, patients frequently have to come off anticoagulation for surgeries, spine injections, bleeding and other issues.

Would you rather have a left atrium that has been maintained in NSR or one that is massively enlarged and dysfunctional if you have to stop your anticoagulation?

The other exam example is of a 74 year old man whose AF was detected at the time of a colonoscopy. When I saw him he was without symptoms with normal lab and cardiac testing. We attempted one cardioversion without anti-arrhythmic drugs and within two weeks he reverted back AF. He elected not to start any anti-arrhythmic drugs and repeat the cardioversion and was doing fine when I saw him 6 months later.

However, shortly after that visit he ended up in severe heart failure with severe left ventricular  dysfunction and severe mitral regurgitation at an outside hospital. This time he agreed with a more aggressive approach to maintenance of SR and after prolonged amiodarone loading and a repeat cardioversion he has maintained SR for 6 months. The function of his left ventricle has improved to near normal (LVEF has increased to 49%) and there is no significant leakage from his mitral valve.

Whereas, most patients who feel fine in AF and elect to stay in it do well there is an unpredictable but significant number who despite adequate rate control develop cardiomyopathy and valvular regurgitation with resulting heart failure.

Medical Maintenance of SR

Yes, I’m convinced that patients can safely and effectively be maintained in SR with medical therapy and the occasional cardioversion.

I try not to fall in the camp of Overtreaters but consider myself a Rational Normal Sinus Rhythm Enthusiast and Advocate.

In my practice when atrial fibrillation reaches a point that requires addition of an anti-arrhythmic medication  I predominantly utilize two such drugs: amiodarone and flecainide.

Patients with structurally  normal hearts do well with flecainide and those with structural heart disease (heart failure, left ventricular hypertrophy, or significant coronary artery disease ) do well with amiodarone when they are monitored closely by a cardiologist with extensive experience using the drugs.

I’ll talk about each of these options  as well as cardiac ablation in detail in subsequent posts.

Antifibrillatorily Yours,

-ACP

Six studies showing no difference in outcomes between rhythm and rate control strategies.

Atrial Fibrillation: How Many Times Can You Shock The Heart?

The most effective method for getting a heart that is in atrial fibrillation back to normal rhythm is a called an electrical cardioversion.

I’ve tried to come up with a good alternative or descriptive term for this procedure for my patients, such as “resetting” or “rebooting” the heart, but the term that seems to best resonate with patients is “shocking” the heart.

How Does Electrical  Cardioversion Work?

Typically, we all can connect (excuse the pun) to the feeling of a low current electrical shock which occurs when touching an ungrounded electrical source.

Unless the current reaches a certain level, it only results in transient burns and discomfort.

However, at current levels greater than 50 mA, an AC electrical shock traveling through the chest can, if timed properly, cause the heart to go out of normal rhythm into ventricular fibrillation.

We use a “synchronized” electrical cardioversion (termed direct current or DC cardioversion (DCC)) to convert a fibrillating or fluttering atrium back to the normal rhythm by timing the electrical shock so that it doesn’t cause ventricular fibrillation but resets both ventricles and atria safely back to normal.

cardioversionAF
Recording from a recent cardioversion I performed on a patient with recurrent atrial flutter/fibrillation associated with heart failure. On the left is the heart rhythm before the shock, and on the right we can see resumption of normal sinus rhythm. The little squiggles labeled p waves represent the electrical activity of the sinus node preceding the big vertical deflections, which represent the electrical activity of the ventricles (QRS). The circled little arrow shows the timing of the shock concurrent with the QRS complexes. If the timing is not correct, the shock can cause ventricular fibrillation.

This may seem like a barbaric and unnecessarily crude and dramatic way to restore normal rhythm, but if patients are properly prepared for this procedure, it is very safe and very effective, resulting in resumption of the normal rhythm 99% of the time.

There are some medications that we can utilize to convert atrial fibrillation (afib) back to normal (antiarrhythmic drugs), but they are far less effective than the electrical cardioversion, and often can bring out more dangerous heart rhythms.

Typically, I do my cardioversions in conjunction with an anesthesiologist, who administers IV propofol (yes, this was Michael Jackson’s sleep aid, his “milk”) to obtain “deep  sedation.” At this level of anesthesia, the patient is breathing on his own but will only respond to painful stimulation. The propofol is short-acting and prevents the patient from feeling the intense pain of the cardioversion (often described as like a mule kicking one in the chest), and from recalling any of the events.

Electrical cadioversion
The skeptical cardiologist calmly prepares to push the “shock” button that will trigger the Zoll device to deliver 150 Joules of biphasic direct current to the electrodes attached to his patient’s chest thereby “ZAPPING” her back to NSR. Should the patient’s heart rhythm be too slow, the Zoll device also can serve as an external pacemaker, triggering cardiac contractions via lower level electrical currents delivered through the chest electrodes.

The electrical shock is administered through electrodes, consisting of large sticky pads with electrical conducting gel attached to the right anterior chest and the left posterior back (see this brief information from Zoll about optimal placement).
Since I began using “biphasic” energy, the initial cardioversion is successful >95% of the time in my experience, but the heart may revert back to atrial fibrillation anywhere from a few minutes to a few years after the shock. We can reduce the chances of reverting back by the use of anti-arrhythmic drugs.

Multiple Shocks: What Is The Limit?

The DCC may need to be repeated, and we may repeat it after starting one of those anti-arrhythmic drugs I mentioned, in order to increase the time that the heart stays in the normal rhythm.

A common question when I recommend a repeat cardioversion is:

“Doc, how many times can you have your heart shocked?”

One might think it is one and done with the shock but it is not a cure; it is merely a resetting of the chaotic, confused and futile activity of the atria, so that the synchronized and regular electrical pacing provided by the sinus node in the upper right atrium can again resume its rightful role as conductor of the cardiac electrical orchestra that creates the wondrous symphony of normal cardiac contraction.

The factors that brought on the afib in the first place likely are still present: if we don’t address correctable factors we are less likely to maintain the normal sinus rhythm (NSR). Correctable factors include:

  • abnormal thyroid function
  • abnormal potassium or magnesium
  • inflammation of adjacent lung or pericardium
  • severe infection
  • obesity (see my post on fat sheep and afib)
  • certain cardiac valve problems

There is no evidence that the cardioversion per se damages the heart in any way. The major risks of the procedure (again, assuming proper preparation, see below) are related to the anesthesia.

I am more inclined to recommend a repeat cardioversion if there is clear-cut evidence that the patient does poorly when the heart is in afib.

Why Shock The Heart?

In medicine, there are two reasons for giving medications and doing surgery/procedures: to make the patient feel better or to reduce the chances of dying/having a major complication.

The major complication of afib is stroke.  Proper anticoagulation is required to prevent this in patients with afib whether or not they are in normal rhythm.  Clots can form in the left atrial appendage within hours of the development of afib, and the electrical cardioversion can increase the chance of stroke as any clot present is more likely to be expelled when the quivering, ineffective atrium converts back to a normally pumping, vigorous  atrium.

Primarily, then, we utilize cardioversion for the purpose of making patients feel better.

Some patients feel terrible the moment they go into afib: symptoms of palpitations, chest pain, or shortness of breath predominate and are especially prominent if the heart rate is high. Controlling the high heart rate with beta-blockers or diltiazem will reduce many of these symptoms, but I have a large number of patients who still feel terrible when they are “out of rhythm,” even if the heart rate is normal. Such patients who persist in afib are good candidates for one or multiple cardioversions, with or without the addition of anti-arrhythmic drugs.

A second group of patients, I think, benefits the most from maintaining sinus rhythm (rhythm control strategy): patients who develop heart failure when they go into AF.

These patients may not even know they are in AF because they don’t feel the typical symptoms initially.  After a few days or weeks or months of being in afib silently, however, they develop shortness of breath, weakness and leg  swelling – classic signs of heart failure.

When we look at the heart of such a patient by echocardiography, we often find one of two things causing the heart failure: a weakening of the heart muscle (cardiomyopathy) or significant leakage/backflow from the mitral valve (mitral regurgitation). Following cardioversion and maintenance of SR for weeks to months, the heart muscle strengthens back to normal and/or the mitral regurgitation improves dramatically and the heart failure resolves.

Multiple Shocks: Rationale

Yesterday I did an electrical cardioversion on an elderly patient of mine  for atrial fibrillation/flutter; this was her fifth DCC in the last year.

She falls into the second category of afib patients; she had developed severe heart failure due to mitral regurgitation after silently going into afib a year earlier. After long-term loading on the anti-arrhythmic drug amiodarone, followed by her fourth cardioversion, she had stayed in NSR for 10 months, her MR resolved, and she felt great. In patients like her, I think it is particularly important to maintain NSR and thus, multiple shocks are definitely warranted.

On the other hand, if you feel fine in afib without any evidence that it is effecting your heart muscle or valves, then it is hard to justify multiple attempts to shock the heart.

Any patient that has recurrent symptomatic afib or afib associated with heart failure, should be considered a candidate for an atrial fibrillation ablation.  The risks and benefits of afib ablation are worthy of another blog post, but the patient-centered afib website stopafib.org has a reasonable discussion here. Suffice it to say, it is a much more complicated and risky procedure than a cardioversion, but it attempts to address the underlying cause(s) of afib, and in some cases creates what could be considered a “cure.”

Cardiovertly Yours,

-ACP

For additional reading:

Here’s a good article from the European Society of Cardiology on cardioversion (https://www.escardio.org/Guidelines-&-Education/Journals-and-publications/ESC-journals-family/E-journal-of-Cardiology-Practice/Volume-11/Cardioversion-in-Atrial-Fibrillation-Described)

and check out what Dr. John Mandrola, an electrophyiologist (cardiologist who specializes in electrical problems of the heart) has to say about afib ablations at Drjohnm.org (http://www.drjohnm.org/2015/09/a-cautionary-note-on-af-ablation-in-2015/)

Credits-Life Coach of the Skeptical Cardiologist (LCOSC) for review of electrical engineering stuff.