Myocardial scar and mortality in severe aortic stenosis: Data from the BSCMR Valve Consortium

Background -Aortic valve replacement (AVR) for aortic stenosis (AS) is timed primarily on the development of symptoms; but late surgery can result in irreversible myocardial dysfunction and additional risk. This study aimed to determine whether presence of focal myocardial scar pre-operatively was associated with long-term mortality. Methods -In a longitudinal observational outcome study, survival analysis was performed in patients with severe AS listed for valve intervention at six UK cardiothoracic centers. Patients underwent pre-procedure echocardiography (for valve severity assessment) and cardiovascular magnetic resonance for ventricular volumes, function and scar quantification between January 2003 and May 2015. Myocardial scar was categorized into three patterns (none, infarct or non-infarct patterns) and quantified using the full-width-at-half-maximum method as percentage of the left ventricle. All-cause and cardiovascular mortality were tracked for a minimum of 2 years. Results -674 patients with severe AS (75±14years, 63% male; AV area 0.38±0.14cm2/m2; mean gradient 46±18mmHg, LVEF 61.0±16.7%) were included. Scar was present in 51% (18% infarct-pattern; 33% non-infarct). Management was surgical (SAVR, n=399) or transcatheter (TAVR, n=275). During follow-up (median 3.6 years), 145 (21.5%) died (52 post-SAVR, 93 post-TAVR). At multivariable analysis, the factors independently associated with all-cause mortality were age (HR 1.50, 95%CI: 1.11-2.04, p=0.009; scaled by epochs of 10 years), STS score (HR 1.12, 95%CI 1.03-1.22, p=0.007) and scar presence (HR 2.39, 95%CI 1.40-4.05, p=0.001). Scar independently predicted all-cause (26.4% vs 12.9%; p<0.001) and cardiovascular mortality (15.0% vs 4.8%; p<0.001), regardless of intervention (TAVR p=0.002, SAVR p=0.026 [all-cause mortality]). Every 1% increase in LV myocardial scar burden was associated with 11% higher all-cause mortality hazard (HR 1.11; 95%CI: 1.05-1.17; p<0.001) and 8% higher cardiovascular mortality hazard (HR 1.08; 95%CI: 1.01-1.17; p<0.001).  Conclusions -In patients with severe AS, late gadolinium enhancement on cardiovascular MR was independently associated with mortality; its presence being associated with a 2-fold higher late mortality.