February 4th, 2015

To Shock or Not to Shock — That Is the Question


About 25% of candidates for cardiac resynchronization therapy (CRT) experience spontaneous reverse remodeling, according to an analysis of the MADIT-CRT study published last year in Circulation: Heart Failure. We now present two perspectives: one from Dr. Jehad Al Buraiki, Director of the Heart Center at King Faisal Specialist Hospital in Riyadh, Saudi Arabia, and another from Joseph G. Akar, Academic Director of Electrophysiology at the Yale School of Medicine in New Haven, Connecticut. The use of CRT-pacemakers is negligible in the U.S. but substantial on the other side of the Atlantic.

Al Buraiki: Management of implantable cardioverter-defibrillators (ICDs) in patients whose LV dysfunction resolves is very challenging and raises tough questions. When is it safe to recommend removal of an ICD in a patient whose LV ejection fraction (LVEF) normalizes? Should an ICD be replaced when the battery voltage depletes in such patients?

Akar: It is instinctively a lot harder to remove an ICD than insert it. Unless you are certain that the initial diagnosis leading to the ICD was erroneous, once an ICD is implanted, no absolute measures ensure safe removal, even if the LVEF completely normalizes.

Al Buraiki: This is exactly why we should be prudent before inserting an ICD. Once implanted, it tends to self-perpetuate. So when do you consider a CRT-pacemaker (CRT-P) rather than a CRT-defibrillator (CRT-D)?

Akar: This is particularly thorny because of the large overlap in clinical indications for CRT-Ps and CRT-Ds, as well as our poor ability to predict CRT responders. So in the U.S. we tend not to use CRT-P because most of these patients also have a defibrillator indication.

Al Buraiki: Our take is quite different. Both CRT-P and CRT-D can affect survival, but they have not been compared head-to-head. Given that patients with advanced heart failure tend to die from progressive pump dysfunction (rather than sudden cardiac death), one must question the incremental benefit of CRT-D over CRT-P. This is particularly true of patients who tend to benefit exceptionally from CRT-P, such as those with nonischemic cardiomyopathy and wide left bundle-branch block. It is also relevant for populations in whom defibrillators are not clearly proven to affect survival, such as the very elderly and patients with renal failure. In fact, for the majority of advanced heart failure patients who are not transplant candidates, sudden cardiac death may actually be more comfortable and humane than progressive pump failure. Multiple defibrillator shocks only make things worse for a patient whose quality of life is the major therapeutic objective. CRT-P improves quality of life and survival without the risk for inappropriate shocks.

Akar: I do not disagree with what you said. It is vitally important to fully engage patients in their clinical care and therapeutic goals when choosing a device, and nonclinical considerations (e.g., cultural, economic, and medico-legal factors) undoubtedly account for the transatlantic differences implantation patterns. Given the large overlap in guideline indications for CRT-P and CRT-D, U.S. physicians usually opt for CRT-D. So it will be crucial for us to distinguish between patients who are best suited for each modality, and to identify patients whose LV function will spontaneously improve and therefore may not need either device. Until that happens, however, we may need to start making some tough choices in an era of increasing economic constraints and limited healthcare dollars, because a strategy of nonselective insertion of a CRT-D is simply not viable from a healthcare economics standpoint.


Where do you stand in the CRT-pacemaker versus CRT-defibrillator debate?

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