Long-term prognostic value of scar characteristics in cardiac magnetic resonance to predict appropriate therapies in primary prevention

Abstract Background Scar characteristics analysed by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are useful to identify patients who will receive appropriate ICD therapies. Indeed, patients without scar and conducting channels are at particularly low risk of ventricular arrhythmias. However, very few studies analyse the value of these LGE-CMR characteristics at long-term follow-up. Objectives This research aims to evaluate the role of scar characteristics in stratifying arrhythmogenic risk in patients with ICD implantation for primary prevention over an eight-year follow-up period. Methods This was a prospective study, between 2006 and 2017, in which we enrolled 200 patients who underwent LGE-CMR before ICD implantation for primary prevention. A dedicated software (ADAS 3D) was employed to automatically quantify scar, border zone, core, and conducting channels (CCs). Results The mean age was 60.9 ± 10.9 years, with 81.5% (163) male participants and 52% (104) with ischemic cardiomyopathy. The average left ventricular ejection fraction was 29% ± 10.1%. After a follow up of 8.2 years (± 2.4), 58 patients (29%) reached the primary end point (appropriate ICD therapy). Scar mass (34.6 ± 18.5 g vs 19.8 ± 12.7 g, P <0.001), border zone mass (25.1 ± 12.2 g vs 14.7 ± 8.3 g, P <0.001), core mass (9.6 ± 8.2 g vs 5.1 ± 5.6 g, P <0.001), and CC mass (2.7 ± 2.5 g vs 1.4 ± 2.3 g, P <0.001) were associated with appropriate therapies. Scar mass > 10 g (hazard ratio 3.41, P 0.018), CCs (hazard ratio 2.84; P 0.0026) and the presence of both Scar mass > 10 g and CCs (hazard ratio 4.43, P 0.012), were also strongly associated with the primary end point. In the same line, patients without channels and with scar mass < 10 g had a very low rate of appropriate therapies (5.5 %). Conclusion Over an 8.2 (± 2.4) years follow-up, scar characteristics analysed by LGE-CMR remain potent predictors of appropriate ICD therapies in primary prevention. Specifically, the absence of conducting channels and scar mass < 10 g effectively identifies individuals at a lower risk of ventricular arrhythmias in this population.