Day 3 at AHA 2013: Top Seven EP Stories: AF Ablation, ICDs, CRT, Dabigatran, and Clinical Effectiveness Research

John Mandrola

November 19, 2013

It was a spectacular day for heart-rhythm news at the American Heart Association 2013 Scientific Sessions . So much so that rather than expand on one topic, I will try to recap seven of the best stories I came across today. Borrowing from the rapid-fire abstract format at the European Society of Cardiology Congress, I'll offer a rapid-fire blog post with one paragraph per topic.

I'm an ablationist, so let's begin with AF ablation news.

Ten-year follow-up for AF ablation: One of the most worthy criticisms of catheter ablation of atrial fibrillation is its high recurrence rate, which worsens over time. The group of Dr Andrea Natale (St David's Medical Center, Austin, TX) released a study of 513 paroxysmal AF patients followed for 10 years. Using their well-validated and consistent approach to pulmonary vein isolation, 59% of patients were arrhythmia-free after a decade. Recurrent arrhythmia between years 5 and 10 occurred in only 5% of patients. Predictors of late recurrence were female sex, left atrial size, and obesity. My take: These are remarkable findings because the late recurrence rate was lower than expected and the overall success rate was quite encouraging. Most important, though, was the fact that the modifiable risk factors, obesity and left atrial size, were strong predictors of recurrence.

Treating AF is a team sport: This is a recap of a chat I had today with the senior author of what I believe to be the most important AF study in decades.Dr Prash Sanders (Centre for Heart Rhythm Disorders, University of Adelaide, Australia) and colleagues, publishing yesterday in the Journal of the American Medical Association, report that weight reduction and intensive risk-factor management resulted in substantial reduction in AF symptom burden/severity and beneficial structural remodeling. Dr Sanders told me that the idea for this study came from patients on his waiting list for ablation. "We aggressively risk-modify all patients. We noticed that for patients who succeeded in actually modifying risk factors, atrial-fibrillation symptoms improved." My take: All parties involved with atrial fibrillation, patients and caregivers alike, must understand that attention to basic lifestyle changes will lead to better outcomes—with or without ablating in the left atrium. Look for more from me on this important study in future posts.

Be careful what you read about AF ablation: The medical literature overflows with studies on AF ablation. Ultimately, most readers want to know one thing: What is the success rate? However, there is no simple answer because reported success rates vary from 10% to 95% and depend on many factors, including varying definitions of success, numbers of procedures, medications taken, and intensity of monitoring. Researchers from Stanford University systematically identified 180 ablation studies with 36 549 patients over a 12-year span. They found significant citation bias among the studies. Reported success rates brought more citations. My take: I agree with the authors, who conclude that AF ablation may seem more effective than the data support. I also like this study because it underscores the importance of critical vetting of science, which is always important, but even more so in this climate of information overload.

Anticoagulation News

GI side effects contribute to the fall of dabigatran . "So the last shall be first, and the first last," said Matthew. In a new meta-analysis of four randomized trials of dabigatran, Dr Ilke Sipahi (University Hospitals and Case Medical Center, Cleveland, OH) and colleagues report that dabigatran increased GI bleeding risk by 41%. This is in sharp contrast to a recent FDA Mini-Sentinel database, which showed a 54% lower risk with dabigatran. Senior heartwire journalist Steve Stiles published this excellent summary on theheart.org on Medscape. My take: Notwithstanding the news of an encouraging study of an IV reversal agent for dabigatran, the first novel anticoagulant is in trouble. Its propensity to cause GI symptoms—often quite severe—is a real problem . . . in the real world. There are now two, and soon three, alternative warfarin substitutes that do not cause these symptoms. What's more, preliminary evidence suggests that dabigatran is inferior to rivaroxaban in the prevention of left atrial appendage thrombus in patients referred for AF ablation. GI symptoms, GI bleeding, comparative efficacy challenges, and twice-daily dosing spell trouble for this early starter.

ICD/CRT News

CRT programming matters: In selected patients, cardiac resynchronization therapy can be a life-changing intervention. But the success of CRT depends on numerous parameters—one of which is device programming. Dr Sina Jamé and colleagues at Stanford University presented intriguing data concerning the prognostic significance of LV pacing lead polarity. The research team analyzed the effects of LV lead polarity of 973 patients who received a CRT-D device as part of the MADIT-CRT trial. Compared with extended bipolar or unipolar programming, true bipolar LV pacing was associated with a significantly lower risk of heart failure or death. My take: The results were convincing and robust but hard to explain. In the Q & A, Dr Jamé said they have studied the data for explanations, but no easy answers have emerged. Stay tuned for more on this one. (I can't help but wonder about underappreciated anodal stimulation.)

Do not implant ICDs during an unplanned hospital admission: The benefit of ICD therapy for selected patients has been well established. The magnitude of this benefit, however, turns on the patient's comorbidities. Recall that most of the patients enrolled in ICD trials were ambulatory outpatients. That said, Dr Garrick Stewart (Brigham and Women's Hospital, Boston MA) and colleagues report that one-third of primary-prevention ICDs placed in Medicare patients were implanted during an unplanned hospitalization to treat another illness. Compared with patients who underwent ICD implants during a scheduled admission, those implanted during an unplanned admission did worse, sustaining a 44% higher rate of complications, 65% higher readmission rate, and an 89% higher risk of death. In a related presentation, Dr Lynne Warner Stevenson (Brigham and Women's Hospital, Boston, MA) presented data from a similar analysis that found ICD use did not confer long-term mortality benefit in Medicare patients when the device was implanted during an unplanned hospitalization. My take: When ICDs are implanted in patients with competing causes of death, not only is benefit muted or eliminated, we expose patients to what I feel is the greatest risk of these devices: the delay of death rather than the extension of life. Reprogramming the mode of death, creating a "bad death," these should be never events for electrophysiologists.

Clinical Research News

Do not ignore the "methods" section of papers: I am an enthusiastic supporter of comparative effectiveness research. As a clinician, the importance of knowing how treatments work in the real world seems self-evident. But observational studies have pitfalls, including the failure to consider selection factors. A group of influential US researchers presented this provocatively titled abstract: "Do ICDs prevent hip fractures, or are physicians selecting appropriate candidates for ICDs?" The experienced research team linked large registry databases and came up with findings that suggested ICD implants reduce the risk of hip fractures by 60%, the risk of nursing-home admission by 47%, and 30-day mortality by 90%. My take: This is beautiful stuff. Of course ICDs don't prevent hip fractures or nursing-home admissions. Rather, this study underscores the pitfalls of observational comparative effectiveness research—namely, that "treatments are not randomly allocated but selected based on specific indications."

For more coverage by my colleagues at theheart.org on Medscape see the AHA 2013 conference page.

Feel free to chime in on whether you liked or disliked the rapid-fire format.

JMM

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