CarDiac magnEtic resonance for prophylactic implantable cardioVerter defibrillAtor ThErapy in ischemic dilated CardioMyopathy: Prognostic implication of papillary muscles involvement

Aims: Implantable cardioverter-defibrillator (ICD) therapy is the most effective prophylactic strategy of sudden cardiac death (SCD) in patients with ischemic cardiomyopathy (ICM). The aim of current analysis is to evaluate the prognostic impact of late gadolinium enhancement-papillary muscles (LGE-PMs) at cardiovascular magnetic resonance (CMR) and specifically its capability to re-stratify the arrhythmic risk on top to the DERIVATE-ICM Risk Score previously published. Methods: Eighty-hundred-thirty-nine patients (mean age 65 ± 11 years; males:721[86%]) with ICM and TTE-LVEF <50% were enrolled from the DERIVATE-ICM registry (CarDiac MagnEtic Resonance for Primary Prevention Implantable CardioVerter DebrillAtor ThErapy- Ischemic Cardiomyopathy). Major adverse arrhythmic cardiac events (MAACE) were the primary endpoints. Results: During a median follow-up of 1054 days, MAACE occurred in 86 (9.7%). DERIVATE-ICM Risk Score quartiles Q2-Q3 (HR:2.124 [95% CI:1.084-4.162]; p = 0.028), Q4 (HR: 3.865 [95% CI: 1.875-7.970]; p < 0.001) and the involvement of isolated posteromedial (P)PM (HR:1.985 [95% CI:1.073-3.673]; p = 0.029) were independent predictors of MAACE. The Kaplan-Meier survival curves showed a higher event-free rate in absence of LGE-PPM in patients categorized in the DERIVATE-ICM Risk Score quartiles Q2-Q3 (p = 0.018). Finally, adding LGE-PPM involvement on top of the model included TTE LVEF<35% plus DERIVATE-ICM Risk Score quartiles Q2-Q3 provided a significant improvement of prognostic stratification (p = 0.044). Conclusion: This study suggests that, in a wide population of ICM patients, LGE-PPM is independently associated with the occurrence of MAACE. In the intermediate quartiles of the DERIVATE-ICM Risk Score, the absence of LGE-PPM, when added to the Score, may contribute to downward re-stratification of arrhythmic risk.