Abstract
AIMS: The effect of primary prevention ICD (ppICD) in non-ischaemic dilated cardiomyopathy (DCM) remains debated. We investigated long-term outcomes and the incidence of ppICD therapy in patients with DCM and ischaemic cardiomyopathy (ICM), comparing implants before and after 2017. METHODS AND RESULTS: We prospectively included ppICD patients from the multicentre IMPROVE study (2014-2022) with DCM and ICM. All underwent ECG and echocardiography at baseline. The primary outcome was appropriate ICD therapy; the secondary outcome was all-cause mortality. Outcomes were compared pre- and post-2017 in DCM and ICM patients. Among 393 ppICD patients (median age 66, 15% female), 115 had DCM (66 post-2017, 49 pre-2017) and 278 had ICM (165 post-2017, 113 pre-2017). DCM post-2017 patients were younger (54 vs. 64 years, P < 0.01) and had a higher left ventricular ejection fraction (LVEF) (33% vs. 24%, P < 0.001) compared to DCM pre-2017 patients. Nevertheless, ICD therapy [4.0 vs. 3.1/100 person-years (PY), P = 0.57] and all-cause mortality rates (2.0 vs. 4.7/100 PY, P = 0.09) were similar. ICM post-2017 patients had a slightly higher LVEF (31% vs. 29%, P = 0.04), fewer ICD therapies (3.1 vs. 6.2/100 PY, P = 0.01), and similar mortality rates (6.3 vs. 8.3/100 PY, P = 0.18) compared to pre-2017. CONCLUSION: Patient selection for ppICD in DCM changed post-2017, with a shift towards younger patients and better LVEF compared to those implanted pre-2017; however, appropriate ICD therapy and all-cause mortality rates remained unchanged. In ICM, lower ICD therapy rates post-2017 may reflect improvement in revascularization and heart failure treatments. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02286908.