Impact of pre-implant cardiac magnetic resonance on arrhythmic outcomes in ICD recipients: insights from a single-center registry

Background Cardiac magnetic resonance (CMR) imaging is increasingly used prior to implantable cardioverter-defibrillator (ICD) implantation, but its clinical impact remains unclear. Purpose We evaluated whether pre-implantation CMR was associated with different rates of appropriate ICD therapies in the follow-up. Methods We retrospectively analyzed consecutive patients who underwent ICD implantation in a single-center Hospital, from March 2016 to February 2024. Subjects were divided according to whether they underwent CMR prior to implantation. The composite endpoint was the occurrence of antitachycardia pacing (ATP) or appropriate shock during follow-up. Comparisons between groups were performed using X², Mann-Whitney, Kaplan-Meier with log-rank test, and multivariable logistic and Cox regression analyses, adjusting for age, left ventricular ejection fraction (LVEF), sex, and cardiomyopathy etiology. Results A total of 226 patients were included: 135 (60%) had undergone pre-implantation CMR (Table 1). Patients with CMR were younger (median age 70.0 years [62.0-76.0] vs. 75.0 [68.5-79.0], p < 0.001), with similar LVEF (median 31.0% [26.0-40.0] vs. 30.0% [28.2-35.8], p = 0.75). During follow-up (median 620 days), the composite endpoint occurred more often in the CMR group (25.2%) than in the non-CMR group (9.9%) (p = 0.0053). In the multivariable analysis, pre-implantation CMR remained independently associated with the endpoint (adjusted OR = 2.94; 95% CI 1.31–6.06, p = 0.0091) (Table 2). The Cox proportional hazards model confirmed this association (HR 2.14; 95% CI 1.55–2.97, p < 0.001) (Table 3). Kaplan–Meier analysis demonstrated significantly lower event-free survival in patients with CMR before ICD implantation (log-rank p = 0.030) (Figure 1). Conclusions In this real-world cohort, a CRM-guided ICD implantation strategy was independently associated with an almost three-fold increased risk of appropriate device therapy during follow-up, despite similar baseline LVEF. These findings may reflect improved identification of arrhythmogenic substrate in patients selected with CMR, but these results require prospective validation.