ADDITIONAL VALUE OF QUANTIFICATION OF MYOCARDIAL FIBROSIS BY CONTRAST-ENHANCED MRI TO IDENTIFY SUBJECTS WITH HYPERTROPHIC CARDIOMYOPATHY AND SUDDEN CARDIAC DEATH RISK

Background . A 5-year sudden cardiac death risk model in line with ESC-2014 (HCM Risk-SCD score) Guidelines assesses the risk of sudden cardiac death in individuals with hypertrophic cardiomyopathy using clinical parameters without taking into account magnetic resonance imaging indices including myocardial fibrosis. Aim . To compare subjects with low, moderate, and high sudden cardiac death risks, identified based on HCM Risk-SCD score, with delayed enhancement magnetic resonance imaging-evidenced fibrosis and to assess the role of fibrosis in identification of patients with sudden cardiac death risk. Material and Methods . A total of 98 patients with hypertrophic cardiomyopathy underwent an integrative examination including cardiac echocardiography, 24-h electrocardiography monitoring, delayed gadolinium-enhanced magnetic resonance imaging, and an assessment of a 5-year sudden cardiac death risk by HCM Risk-SCD score. Results and Discussion . Out of 98 patients, 45 (46%) patients had low risk of sudden cardiac death, 26 (26%) patients had intermediate risk, and 27 (28%) patients had high sudden cardiac death risk by HCM Risk-SCD score. During the follow-up period, (mean 41 months; 25 to 58 months), 16 adverse events were registered: sudden cardiac death occurred in 9 patients while 7 patients had been successfully resuscitated and implanted with implantable cardioverter defibrillator for secondary prevention of sudden cardiac death. The risk assessment using HCM Risk-SCD score showed high risk in 8 out of 16 (50%) patients; 2 (12.5%) patients had moderate risk, while 6 (37.5%) patients had low risk. High-risk patients demonstrated significantly (p<0.001) larger fibrosis (mean 28.5%; quartiles 21.9%; 44.1%) compared to those with moderate risk (mean 17.6%; quartiles 8.0%; 22.5%) and low risk of sudden cardiac death (mean 11.7%; quartiles 5.8%; 17.6%). The volume of fibrosis by delayed contrast-enhanced magnetic resonance imaging was associated with the adverse outcomes rate, which was 15%. A Log rank test in the KaplanMeier survival analysis showed statistically significant differences (p=0,002) in groups with fibrosis <15% and≥15%. The regression analysis showed that myocardial fibrosis was more significant factor associated with sudden cardiac death (OR 12; 95% CI 1.6–91) compared to SCD ESC-2014 score (OR 2.8 95% CI 1.1–7.5). Conclusion . Therefore, based on regression analysis, patients with hypertrophic cardiomyopathy who had myocardial fibrosis volume ≥15% were identified as a group with risk of sudden cardiac death and adverse arrhythmic events.