Prophylactic implantable cardioverter-defibrillators may decrease mortality in left ventricular dysfunction

1. Survival at 3 years was significantly better in patients with a left ventricular ejection fraction (LVEF) between 30% and 35% and an implantable cardioverter-defibrillator (ICD) compared to matched patients without an ICD. 

2. Survival at 3 years was also significantly better in patients with LVEF < 30% and an ICD compared to matched patients without an ICD. 

Evidence Rating Level: 2 (Good)            

Study Rundown: Implantable cardioverter-defibrillators (ICDs) prevent sudden cardiac death in patients with systolic heart failure and low left ventricular ejection fraction (LVEF). Randomized clinical trials have investigated the survival benefit of prophylactic ICDs using the inclusion criteria of LVEF < 35%. However, most participants in these studies have LVEFs much lower than 30% and the outcomes of patients with LVEF between 30% and 35% have not been well studied.

This study examined the survival benefit of prophylactic ICD placement in patients with a LVEF between 30% and 35% and those with a LVEF less than 30%, and found a benefit at 3 years post-placement for both. This study was limited by its restriction to Medicare patients and the incomplete nature of some aspects of the clinical databases that were utilized. Thus, future studies may aim to increase the generalizability of these findings and may be able to capture more complete data through a prospective approach. Moreover, additional measures may be examined in addition to all-cause mortality, such as quality of life and procedural complications. Nevertheless, at this time, this study demonstrates the survival benefit of prophylactic ICD placement in patients with LVEF less than 35%.

Click to read the study in JAMA

Relevant Reading: Prophylactic Implantation of a Defibrillator in Patients with Myocardial Infarction and Reduced Ejection Fraction

In-Depth [retrospective cohort]: This study was a retrospective cohort in which patients with an LVEF between 30 and 35% who received a prophylactic ICD during a heart failure hospitalization (n=408) were matched to patients with no ICD (n=408). At 3 years, 51.4% of the patients with prophylactic ICD had died compared to 55.0% of the patients without ICDs, demonstrating a significantly lower risk of mortality in patients with an ICD (HR 0.83 [95% CI 0.69-0.99], p=0.4).  The same analysis was performed on patients with LVEF < 30% with a prophylactic ICD (n=1088) matched to patients with no ICD (n=1088). At 3 years, 45.0% of patients with ICDs had died compared to 57.6% of the patients without ICDs. Similarly, patients with ICDs had a significantly lower risk of mortality (HR 0.72 [95% CI, 0.65-0.81], p<0.001).

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