Dr John Mandrola practices cardiac electrophysiology in Louisville, KY. He finished training at Indiana University in 1996. His practice encompasses catheter ablation, including an eight-year experience with AF ablation, device implantation, and consultative EP. Outside of the EP lab, Dr Mandrola's two hobbies include competitive cycling and writing. He has maintained a medical, fitness, and cycling blog, Dr John M, for the past two years.
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The changing role of rhythm-control medicines for AFAug 4, 2012 18:24 EDT
I get a lot of questions about heart-rhythm drugs. You probably do, too. They have been around for so long, it's easy to forget just how complicated they are. These are potent chemicals that manipulate complex cardiac channels. That makes me nervous. It's one thing to prescribe flecainide; it's yet another to swallow the hard white pill yourself.
To be specific, I am talking about the sodium-channel blockers propafenone (Rhythmol, GlaxoSmithKline) and flecainide, the potassium channel blockers sotalol and dofetilide, and the multichannel blockers dronedarone and amiodarone.
As an exercise, put yourself in the shoes of a patient-safety advocate assigned to study the use of rhythm-control meds for atrial fibrillation. The first thing an outside observer would notice is how poorly these drugs work—in less than half the cases. Then they'd cringe when reading about proarrhythmia. A partially effective drug that slows the heart rate so much that a permanent in-dwelling vascular device must be implanted; this is acceptable? Or worse: AF drugs can perpetuate truly dangerous tachycardia like 1:1 atrial flutter or torsades de pointes. And if inefficacy and dangerous proarrhythmia were not enough, there's also the side effects: metallic taste, fatigue, dyspnea, blurred vision, balance problems, and stomach upset, among so many others. Ouch. How did these drugs get approved? What will we think 20 years from now?
But yet, those of us who treat AF recommend these medicines every day. Not all AF patients are best treated with catheter ablation or a rate-control approach.
Given the "new" landscape of AF therapy, perhaps it might be reasonable to reflect on how these medicines fit into the current-day treatment of AF. So much has changed: on the one hand, mere mortals can safely ablate AF in two hours. On the other hand, we are gradually learning that more treatment might not always be the best strategy. Less-is-more thinking now enjoys a strong tailwind.
Five ideas about rhythm control medicines come to mind:
Consider individuals vs populations: Even though rhythm meds work for AF less than half the time, if they work for you, it counts as a 100% success rate. This happens. We all have these patients.
To foster AF remission: I often tell AF patients "what was isn't always what is or what will be." Things can change. We know that AF begets AF and that regular rhythm probably begets regular rhythm. I often use rhythm meds as an initial tempering measure. Let's get things settled down and then talk about weaning off the medicine in the future. Sometimes AF passes as mysteriously as it comes.
To promote atrial remodeling before ablation: As an AF ablationist, I'm often using rhythm meds to prepare patients for ablation. For years, it has been clear to me that converting persistent AF to intermittent AF before ablation made sense. It's exciting to read that this strategy reduced the intensity of ablation needed to achieve success .
To buy time: We see a great deal of lifestyle-associated AF in Kentucky. I often use rhythm drugs to give symptomatic AF patients a window of time to right their ship. You know the cycle: AF makes it tough to exercise; lack of exercise causes weight gain, which then worsens blood pressure and sleep, which then sustains AF, and sustained AF leads to atrial structural disease. If you can get a patient in sinus rhythm, you can give them an opportunity to help themselves. They can run (or walk or cycle) with the vigor that sinus rhythm brings.
This would be a good place to mention the incredibly novel drug dofetilide (Tikosyn, Pfizer). Although it's tricky to use, I often find it surprising helpful in seemingly hopeless cases of persistent AF. The word miraculous comes to mind. I've seen dofetilide superresponders—sometimes with both dilated bellies and dilated atria—convert with one oral dose and then remain in regular rhythm for years. When this happens I turn up the volume on lifestyle: "Wow . . . Congratulations. . . . Now that you are in sinus rhythm, you need to get moving. You can help yourself." Seriously, this is a beautiful event—even though Pfizer did it, not me.
One more thing on buying time: AF ablation has come a long way over the past 10 years. It's now a "normal" procedure. But still, from a patient's perspective, it's far from easy or small. Redo procedures are common, and life-changing complications can happen. Surely AF ablation will get better in the future. So here's another area for using rhythm-control medicines. Let's say a medicine is nicely controlling AF. Why not wait to ablate? AF ablation will not be any different in the next month, but it will surely be better in two years.
Pill in the pocket: The pill-in-the-pocket technique appeals to me. It's not just that the strategy graced the pages of the New England Journal of Medicine, it also jives with my minimalist bent. What's better: taking two pills a year for two AF episodes or 760 pills for suppressing the two episodes?
Even though most of the pill-in-the-pocket studies evaluated rhythm-control drugs, I've had modest success, especially in cases of early or adrenaline-sensitive AF, with simple beta blockers taken as needed for episodes. (Think safety. Think empowering the patient. Think staying out of the ER.) For patients who are well-educated on their disease, have infrequent episodes of AF, and been evaluated by an expert who has assessed the appropriateness of the drug, this minimalist technique can work well. I've even used it on myself.
Surely there are many other good reasons to use rhythm drugs for treating AF.
It would be cool to hear your ideas.