Abstract 4368224: Serial Myocardial Fibrosis Assessments Predict Outcomes in Patients with Hypertrophic Cardiomyopathy

Background: The prognostic value of serial myocardial fibrosis assessments in patients with hypertrophic cardiomyopathy (HCM) remains to be elucidated. Objectives: To investigate the progression of late gadolinium enhancement (LGE), as assessed by follow-up cardiac magnetic resonance (CMR) imaging, in patients with HCM, as well as its associated prognostic value. Methods: Patients with HCM who underwent two CMR examinations between 2010 and 2019 were retrospectively evaluated. The LGE mass progression (ΔLGE%) was defined as the number of increased grams of enhanced myocardium added divided by the number of years between the two scans. Primary endpoint was the combination of cardiac death, heart transplantation, aborted sudden cardiac death (SCD), appropriate implantable cardioverter defibrillator discharge, hospitalization for heart failure and stroke. Secondary endpoint was the combination of cardiac death, aborted SCD and heart transplantation. A maximally selected rank statistical analysis was conducted to identify the optimal cut-off for ΔLGE% for prognostic stratification. Results: A total of 313 patients with HCM (median scan interval: 4.2 years) were evaluated. LGE mass progressed from a median of 2.9 (Q1-Q3: 0.0 to 8.1) g at CMR-1 to 8.3 (Q1-Q3: 3.6 to 16.3) g at CMR-2. During a median follow-up of 7.7 (Q1-Q3: 6.0-9.8) years from initial CMR, the primary endpoint occurred in 66 patients, of whom 22.7% reached the secondary endpoint (n=15). For primary endpoint and secondary endpoint, the optimal cut-off for ΔLGE% were >1.50 and 3.75g/year, respectively. In the multivariable model, New York Heart Association class III/IV at baseline (HR 5.39, 95% CI: 2.92-9.94, P <0.0001), left ventricular ejection fraction <50% at CMR-1 (HR 2.65, 95% CI: 1.27-5.52, P =0.0096), and ΔLGE% >1.50g/year (HR 5.86, 95% CI: 3.41-10.08, P <0.0001) were associated with the primary endpoint. Conclusions: In HCM patients, myocardial fibrosis increased over time. Serial assessments of myocardial fibrosis on CMR may improve risk stratification and clinical decision-making in HCM patients.