Background The benefit of implantable cardioverter defibrillator (ICD) therapy in patients who have heart failure with improved left ventricular ejection fraction (LVEF) to >35% after implantation (HFimpEF) is controversial. Methods Databases (Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar) were queried for studies of ICD patients that reported the association between HFimpEF and arrhythmic events (AEs), defined as the combined incidence of ventricular arrhythmias, appropriate ICD intervention and sudden cardiac death (primary composite endpoint). Results A total of 41 studies and 38,572 patients (11,135 with HFimpEF, 27,437 with persistent EF <35%) were included; mean follow up was 43 months. HFimpEF was associated with decreased AEs (OR 0.39, 95% CI 0.32-0.47; annual rate (AR) 4.1% vs. 8%; P<0.01). Super-responders (EF >50%) had a lower risk of AEs than patients with more modest reverse remodeling (EF>35% and <50%, OR 0.25, 95% CI 0.14-0.46; AR 2.7% vs. 6.2%; P<0.01). HFimpEF patients who had an initial primary prevention indication had a lower risk of AEs (OR 0.43, 95% CI 0.3-0.61; AR 5.1% vs. 10.3%; P<0.01). Among primary prevention patients who had never received appropriate ICD therapy at the time of generator change, HFimpEF was associated with decreased subsequent AEs (OR 0.26, 95% CI 0.12-0.59; AR 1.6% vs. 4.8%; P<0.01). Conclusion HFimpEF is associated with reduced, but not eliminated, risk for AEs in patients with ICDs. The decision for replacing an ICD in lower risk subgroups should incorporate shared decision making based on risks for subsequent AEs and procedural complications.

Background: As the volume of cardiac imaging continues to increase, so is the number of tests performed for rarely appropriate indications. Appropriate use criteria (AUC) documents were published by professional societies with quality improvement (QI) interventions developed in various institutions. However, the effectiveness of these interventions has not been assessed in a systematic fashion. Methods: We performed a database search for studies reporting the association between cardiac imaging, AUC and QI. We selected studies assessing the effect of QI interventions on performance of rarely appropriate echocardiograms. The primary endpoint was reduction of rarely appropriate testing. Results: Nine studies with 22,070 patients met inclusion criteria. QI interventions resulted in statistically significant reduction in rarely appropriate tests (OR 0.52, 95% CI 0.41-0.66; p<0.01). The effects of QI interventions were analyzed over both the short (< 3 months) and long-term (> 3 months) post intervention (OR 0.62, 95% CI: 0.49-0.79; p<0.01 in the short term, and OR 0.47, 95% CI: 0.35-0.62; p<0.01 in the long term). Subgroup analysis of the type of intervention, classified as education tools or decision support tools showed both significantly reduced rarely appropriate testing (OR 0.54, 95% CI: 0.41-0.73; p<0.01; OR 0.47, 95% CI: 0.36-0.61; p<0.01). Adding a feedback tool did not change the effect compared to not using a feedback tool (OR 0.49 vs. 0.57, 95% CI: 0.36-0.68 vs. 0.39-0.84; p>0.05). Conclusion: QI interventions are associated with a significant reduction in performance of rarely appropriate echocardiography testing, the effects of which persist over time.