Cardiac magnetic resonance for prophylactic implantable-cardioverter defibrillator therapy international registry: prognostic value of LGE distribution in non-ischemic dilated cardiomyopathy
Authors: Guaricci A I , Carrabba N C , Romano S R , Chiostri M C , Basile P B , Mushtaq S M , Baggiano A B , Fazzari F F , Fusini L F , Volpe A V , Pradella S P , Schwitter J S , Pontone G P 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public Institution(s). Main funding source(s): This work was supported by Italian Ministry of Health, Rome, Italy (RC 2017 R659/17-CCM698).

Background/Introduction
Tissue characterization obtained by cardiac magnetic resonance (CMR) has emerged as a promising tool for better identification of non ischemic cardiomyopathy patients at high arrhythmic risk and thus worthy of prophylactic ICD therapy.

Purpose
Current analysis has the scope to assess the prognostic value of fibrosis, as evaluated by late gadolinium enhancement sequences (LGE) specifically regarding its LV wall distribution, and a CMR-derived risk score. The primary endpoint was all-cause mortality. The secondary end-point consisted of major adverse arrhythmic cardiac events (MAACE), defined as combination of SCD, aborted SCD, and sustained ventricular tachycardia

Methods
DERIVATE Study is an international, multicenter, prospective, observational registry including consecutive patients from 21 sites referred for heart failure (HF) work-up including transthoracic echocardiography (TTE) and CMR without a history of previous major ventricular arrhythmias. Inclusion criteria were: (i) aged 18 or older, (ii) chronic HF, and (iii) LV-EF&lt;50% at initial TTE. All patients underwent TTE and CMR within 3 months. Patients with (i) decompensated within 3 months of enrollment, (ii) recent myocardial infarction (&lt;40 days), (iii) unstable angina, (iv) severe valvular disease, (v) primary or secondary cardiomyopathies other than NICM, (vi) cardiac amyloidosis, and (vii) congenital heart disease were excluded.

Results
The entire cohort consisted of 1384 subjects [mean age: 56±14 years, male: 948 (68.4%)]. The median follow-up time was 959 days. Mortality and MAACE occurred in 92 (6.6%) and 125 (9%) patients, respectively. SCD, aborted SCD, and sustained VT occurred in 15 (1.1%), 80 (5.8%), and 104 (7.5%), respectively. The sum of events exceeds the overall number of MAACE because several events could occur in the same patients but just the first event was counted. In the multivariate analyses for all-cause mortality, only the number of segments with LGE at the level of the septum was an independent predictor (p = 0.002), while in the analyses for MAACE the only independent predictors were male gender, LVEDVi by CMR, and the number of segments with LGE at the level of septum inferior. Based on the multivariate analysis, the DERIVATE score (including all 1384 patients) ranging from 0 to 8 (Cox regression analysis HR=1.35, 95%CI 1.24–1.46, p&lt; 0.001) was realized. The redistribution of patients according to the CMR composite DERIVATE risk/year MAACE was of 44%, 37% and 32% for the low, intermediate and high risk groups, respectively.

Conclusions
The arrhythmic risk of patients with NICM is also dependent on the different distribution of fibrosis in the LV. The redistribution of the event rate according to the CMR composite risk score indicates the potential to alter the decision on ICD implantation in a relevant portion of NICM patients. These results warrant further confirmation in prospective randomized controlled trials.