The American College of Cardiology, American Heart Association, and Heart Rhythm Society have published guidelines that provide patient selection criteria for the use of implantable cardioverter-defibrillators (ICDs) as primary prevention. ICDs can be life-saving therapy for appropriate patients with cardiac abnormalities. Studies, however, suggest that guideline discordant practice is common. To further analyze this phenomenon, my colleagues and I conducted a study that was published in the February 2, 2012 issue of Heart Rhythm. We wanted to determine referring physicians’ concordance with the primary prevention ICD guidelines.

Assessing Guideline Concordance & Discordance

According to our findings, 28% of respondents never referred patients to specialists with the intent of considering them for a primary prevention ICD; 7% of such responses were seen in cardiologists. Many respondents didn’t understand left ventricular ejection fraction (LVEF) criteria or that ICDs can be indicated in the absence of ventricular arrhythmias. Guidelines-discordant responses were common overall:

15% reported that an ICD is never indicated in the absence of a ventricular arrhythmia.
6% reported that an LVEF greater than 40% can warrant a primary prevention ICD.
25% reported that they would refer a patient for a primary prevention ICD within 40 days of a myocardial infarction (MI).

Family practitioners and physicians residing in the western part of the United States were most likely to provide guideline-discordant answers to the survey when compared with other respondents. General cardiologists and those who referred patients to electrophysiologists were more likely to answer survey questions in ways that were considered concordant with the guidelines. Discordant responses, however, were not unusual among general cardiologists; 4% reported that an ICD isn’t indicated without ventricular arrhythmias, and 19% said they would refer a patient within 40 days of an MI. About one-quarter of cardiologists reported that an ICD can be indicated with an LVEF greater than 40%. Regarding primary care physicians, about 25% managed at least 40% of their low- LVEF patients without cardiologist referrals.

Wanted: Greater Awareness, More Education

Based on our findings, it appears that referring physician beliefs are an important barrier to appropriate patient referrals for primary prevention ICD implantation. It’s clear that these physicians should be targeted in terms of education regarding ICDs. Unfortunately, when CME sponsors are developing courses on cardiology guidelines, cardiologists are usually the primary focus. To improve referral patterns, it’s imperative that greater efforts are made to increase awareness of guidelines and enhance education for other providers.

It’s imperative that greater efforts are made to increase awareness of guidelines and enhance education for other providers.

There are many reasons that can come into play when patients are not referred for ICDs. Our study revealed that patient preference and concern over ICD-related infections had an important influence, but there were few concerns over inappropriate shocks or device recalls. This suggests many physicians do not consistently follow guideline recommendations on referring for ICD implantation because they’re adding their own interpretations to the evidence base. While all patients who meet guidelines criteria will not require an ICD, it’s important to at least provide patients with an opportunity to hear the pros and cons of implanting an ICD from expert electrophysiologists.