Evidence of clinical practice heterogeneity in the use of implantable cardioverter-defibrillators in heart failure and post-myocardial infarction left ventricular dysfunction: Findings from IMPROVE HF

BACKGROUND Clinical guidelines recommend implantable cardioverter-defibrillators (ICDs) for selected patients with chronic left ventricular dysfunction (LVD) to improve survival, yet ICD treatment rates for eligible patients with LVD or heart failure (HF) in cardiology practices remain poorly studied. OBJECTIVE This study sought to determine patient and practice characteristics associated with ICD use in the outpatient setting. METHODS IMPROVE HF (Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting), a prospective cohort study, is designed to characterize management of HF with reduced left ventricular ejection fraction (LVEF <= 35%). Baseline data were collected for 15,381 patients attending 167 outpatient cardiology practices located in the U. S. RESULTS By current guidelines, 7,221 patients met eligibility for ICD implantation (+/- cardiac resynchronization therapy [CRT]), of whom 3,659 (50.7%) received either ICD (63.8%) or CRT with defibrillator (36.2%). Individual practice conformity for guidelinerecommended ICD use ranged from 0% to 100% (27.3% to 74.6% at the 10th and 90th percentiles, respectively). Adjusted analyses revealed lack of adherence for ICD use most notably with advancing age (odds ratio: 0.87; 95% confidence interval: 0.82 to 0.93 per 10 years), black race (odds ratio: 0.75; 95% confidence interval: 0.60 to 0.94), and lack of insurance (odds ratio: 0.45; 95% confidence interval: 0.26 to 0.78). Characteristics of increased adherence included male sex, ischemic disease, atrial fibrillation, and wider QRS. Practices in the Northeast U. S. were more likely to adhere to guidelines (P < .001), as were those with a dedicated HF clinic (P = .004) and electrophysiologists on staff (P < .001). CONCLUSION Although a number of patient and practice characteristics are associated with guideline-based ICD use, there is significant unexplained variation in the use of ICD therapy for sudden death prophylaxis across cardiology practices.