ACE inhibitors and ARBs have a protective effect on patients with cardiomyopathy who receive implantable cardioverter-defibrillators (ICDs), according to an analysis presented May 8 at the Heart Rhythm Society scientific session in San Francisco.

“ICD shocks are not only painful but they can be associated with morbidity and mortality,” Patrick T. Ellinor, MD, PhD, an electrophysiologist at of Massachusetts General Hospital in Boston, explained in an interview with Cardiovascular Business. Given the benefits of ACE inhibitors and ARBs on cardiovascular mortality in general, Ellinor and colleagues reasoned that the drugs likely would reduce the incidence of appropriate ICD shocks as well.  

They used data from the GRADE study (Genetic Risk Assessment of Defibrillator Events), which assessed whether certain genetic variations were associated with arrhythmias in patients with ICDs and an ejection fraction of 30 percent or less. Patients were enrolled between 2002 and 2010, with a five-year follow-up.

The ACE inhibitor/ARB analysis included 1,509 patients, mostly men, with a mean age of 63 years and a mean ejection fraction of 21 percent. Eighty percent were on ACE inhibitors or ARBs. After propensity matching, they found that at a mean 2.5 years, 22 percent of the entire group had appropriate shocks.

The proportion of patients to receive appropriate shocks was lower in ACE inhibitor/ARB group compared with the untreated group: at one year, 8.7 percent vs. 13.5 percent; at three years, 17.1 percent vs. 23.6 percent and at five years, 20 percent vs. 27.4 percent.

A multivariate analysis showed that ACE inhibitors/ARBs were associated with more than a 40 percent reduction in the incidence of an appropriate shock. “Everybody knows that patients with a low ejection fraction should be on an ACE inhibitor or ARB, but this is one more bit of evidence that shows they really should be on one,” Ellinor said.

They hypothesize that the benefits were due to the effects of ACE inhibitors and ARBs on remodeling and cardiovascular function. “What we have is a clinical observation," he said. "The mechanism behind it is difficult to know.”