The Need for Defibrillator Therapy Continues in Patients with Heart Failure

Major defibrillator trials such as SCD-HeFT showed a mortality benefit in patients with heart failure and reduced ejection fraction (HFrEF),^1,2 led to our current guideline-based indications for device therapy, and informed Medicare reimbursement guidelines. However, these studies were performed many years ago. Since then, medical therapies for heart failure patients have greatly improved and resulted in greater patient longevity.

In recent years, there has been evidence to suggest that modern medical therapy is now so effective that defibrillator therapy may no longer be offering a significant mortality benefit to patients with advanced heart disease. For example, the DANISH trial showed no additional benefit to defibrillator therapy in patients with heart failure who were treated with cardiac resynchronization pacing therapy (CRT).³ In addition, a recent meta-analysis of heart failure trials showed that there has been a significant reduction in sudden death over the past two decades as new medications have become available for HFrEF. This information implies that defibrillators may not be having the same impact on overall mortality that they had in the past.⁴

However, a recent study strongly suggests that there remains a role for implantable defibrillator therapy in patients with HFrEF, and are underutilized. Presented at the European Society of Cardiology (ESC) Congress 2019 together with the World Congress of Cardiology and published simultaneously in Circulation,⁵ Schrage et al provided a contemporary analysis from the Swedish Heart Failure Registry of the association between the use of primary prevention implantable defibrillators and mortality in patients with HFrEF. They identify nearly 17,000 patients who (based on the registry) fulfilled the ESC criteria for a primary prevention defibrillator. Interestingly, they found that only 10% of patients who met these criteria had an implantable defibrillator. After performing a propensity score-matched analysis, they found a statistically significant major reduction in all-cause mortality at one year, with a hazard ratio of 0.73, and at five years, with a hazard ratio of 0.88. Equally impressive was a subgroup analysis, which showed that all groups of patients — regardless of the etiology of their heart failure, sex, age, or concomitant cardiac resynchronization therapy — benefited from defibrillator therapy. They concluded from this contemporary analysis that implantable defibrillator therapy for primary prevention in patients with HFrEF who are being treated with modern medical therapy continues to be associated with a significant reduction in short- and long-term all-cause mortality, and is underutilized.

It is important that we periodically reevaluate the role of implantable device therapy for the primary prevention of sudden death to make sure we are continuing to help patients. Although there have been some recent indications that, with improved medical therapy for heart failure over the past two decades, defibrillator therapy may be having less of an impact in helping patients live longer, this contemporary analysis from a large Swedish registry strongly suggests otherwise.

Disclosure: Dr. Knight reports that he is a consultant, speaker, investigator, and offers fellowship support for Abbott, Baylis Medical, Biosense Webster, Inc., BIOTRONIK, Boston Scientific, Medtronic, and SentreHEART.

1. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005;352:225-237.
2. Desai AS, Fang JC, Maisel WH, Baughman KL. Implantable defibrillators for the prevention of mortality in patients with nonischemic cardiomyopathy: a meta-analysis of randomized controlled trials. JAMA. 2004;292:2874-2879.
3. Kober L, Thune JJ, Nielsen JC, et al. Defibrillator implantation in patients with nonischemic systolic heart failure. N Engl J Med. 2016 Aug 27. DOI:10.1056/NEJMoa1608029.
4. Shen L, Jhund PS, Petrie MC, et al. Declining risk of sudden death in heart failure. N Engl J Med. 2017;377:41-51.
5. Schrage B, Uijl A, Benson L, et al. Association between use of primary prevention implantable cardioverter-defibrillators and mortality in patients with heart failure: a prospective propensity-score matched analysis from the Swedish Heart Failure Registry. Circulation. 2019 Sep 3. DOI: 10.1161/CIRCULATIONAHA.119.043012.