Predictive value of scar burden assessed by cardiac MRI on sudden cardiac death in cardiac resynchronization therapy patients: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Innovation and the National Research, project no. RRF-2.3.1-21-2022-00003 and Project no. RRF-2.3.1-21-2022-00004 (MILAB) has been implemented with the support provided by the European Union. Background Myocardial fibrosis (MF) is associated with a higher prevalence of ventricular arrhythmias (VA) and sudden cardiac death (SCD). Late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) can accurately evaluate the extent of MF. Clinical evidence suggests that scar assessment may help the decision of adding an implantable cardioverter defibrillator (ICD) to cardiac resynchronization therapy (CRT) to reduce the risk of VA and SCD. Purpose In this systematic review and meta-analysis, we collected and analyzed evidence pertaining to the association between scar burden and the risk of VA and SCD, and we evaluated the impact of appropriate device choice for CRT. Methods We performed a systematic literature search on MEDLINE using the PubMed, Embase, Scopus and CENTRAL databases. The target population were adults with heart failure with reduced ejection fraction who underwent CRT. The primary outcome was the association between the incidence of VA and/or SCD and scar burden assessment. Meta-analyses were performed using the META and DMETAR packages in R, using a random-effects model. The risk of bias was assessed using RoB2and the quality of evidence was evaluated using the GRADE assessment. Results 6 eligible articles have been included in our study, with a total of 1548 patients, of whom 465, 696, and 387 have been implanted with an ICD, CRT-D, CRT-P respectively. Altogether 62,68 % of the total population were LGE-CMR positive. The proportion of appropriate ICD shock reached 15,65 % in the total population during the median follow-up time of 51,59 months. The risk of developing appropriate ICD shocks in the LGE positive population was almost 70% higher (Hazard ratio 1,69, 95% Confidence interval: 1,29- 2,21; p<0,001) compared to LGE negative patients. Conclusion In our meta-analysis, LGE-CMR was significantly associated with appropriate device therapy and can identify a subgroup of patients with an increased risk of life-threatening VA. Based on our results performing an MRI before device implantation might be important to select the high-risk patients for SCD in the elderly with ischaemic etiology and older age.