Vice President Cheney Gets Atrial Fibrillation

Well, it was bound to happen.

Take a man with significant coronary artery disease, a prior history of more than enough cardiac bypass operations, a weakened heart muscle that requires an automatic defibrillator, and a prior deep venous thrombosis (blood clot) in his leg and what to you get? An almost inevitable likelihood that he will develop a heart rhythm disturbance, too.

It seems Vice President Dick Cheney has suffered another common complication of a weakened heart: atrial fibrillation (afib).

Atrial fibrillation, characterized by an irregular heart rhythm disturbance in the upper chambers of the heart (atria), becomes symptomatic in a variety of ways:

• It can made the lower chambers of the heart (ventricles) race too fast
• It can cause an uncomfortable irregularity of the heart rhythm that can be disturbing to the individual (called "palpitations")
• It can reduce the efficiency of the pumping action of the heart, making people feel more short of breath or perhaps develop a slight cough (as the above article suggests)
• Or, commonly, it can be completely silent and not cause any symptoms.

But by far and away the main concern with afib in someone like Mr. Cheney is its propensity to increase his risk of stroke. Fortunately for Mr. Cheney, however, this risk was minimized because he was probably taking warfarin (Coumadin®) for treatment of the earlier blood clot in his leg. More ominously, however, the presence of his persistent cough may have represented congestive heart failure (where fluid backs up into the lungs) caused by the reduced efficiency of his heart to pump blood in this rhythm.

Afib that occurs in someone who already has an automatic defibrillator presents additional therapeutic challenges. In defibrillator patients, if afib causes the heart to race too fast, the heart rate could exceed the rate limit in the defibrillator's pre-programmed settings that helps it separate normal from abnormal heart rates. If the lower chamber (ventricular) rate exceeds this limit, then the device might detect the rhythm as excessive, charge, and deliver a shock to attempt to correct the rhythm. If the shock encompasses the upper chambers sufficiently, it can restore the atrial fibrillation rhythm back to normal. If not, the lower chambers can be driven progressively faster by the upper chambers again, and additional shocks could occur. To prevent this, rate control medications (such as beta blockers) are an important therapeutic strategy.

So what usually happens next?

First, the White House really doesn't want or need this publicity. So the most logical step will be to convert Mr. Cheney's heart rhythm back to normal quickly. Provided he is on adequate anticoagulation, this could be performed right away, often using his defibrillator to restore his atrial rhythm to normal (an "internal" cardioversion) while sedated. If unsuccessful, a more conventional "external" cardioversion could be performed by applying a jolt of electricity across his chest to reset the heart rhythm - much like one hits "Alt-Ctrl-Del" on a PC to reboot it (sorry, I digress...) If these methods are objectionable to Mr. Cheney, pharmachologic cardioversion with a medication like ibutilide (Corvert®) could also be attempted. By restoring the rhythm back to normal quickly, Mr. Cheney loses his star power before the media and gets back to his business as Vice President. And as predicted, it's already been done.

Long-term, there will be a discussion if Mr. Cheney should remain on an anti-arrhythmic medication. This will most likely depend on the severity of symptoms he experienced with his afib. If the symptoms were deemed severe enough, he might placed on a medication to attempt to maintain normal atrial rhythm. The efficacy of these anti-arrhythmic medications are at best about 60% effective long-term at maintaining normal rhythm after one year. On the other hand, if his symptoms were minimal, then a rate-control medication (i.e., beta blocker) coupled with anticoagulation might be the better long-term option.

It would seem unlikely that Mr. Cheney would opt for primary catheter ablation of his atrial fibrillation right now, especially given the inherent risks to the procedure, but should the medicines prove ineffective at managing his symptoms, or if his atrial fibrillation rates prove difficult to control with medications alone, then catheter ablation might offer some effective therapeutic options.

No matter how you cut it, though, this rhythm disturbance is likely to be a recurrent problem for Mr. Cheney. Hopefully, its effects can be minimized with close management and follow-up.

-Wes