Myocardial Scar and Mortality in Severe Aortic Stenosis

Abstract

Background: Aortic valve replacement (AVR) for aortic stenosis is timed primarily on the development of symptoms, but late surgery can result in irreversible myocardial dysfunction and additional risk. The aim of this study was to determine whether the presence of focal myocardial scar preoperatively was associated with long-term mortality.

Methods: In a longitudinal observational outcome study, survival analysis was performed in patients with severe aortic stenosis listed for valve intervention at 6 UK cardiothoracic centers. Patients underwent preprocedural 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 3 patterns (none, infarct, or noninfarct patterns) and quantified with the full width at half-maximum method as percentage of the left ventricle. All-cause mortality and cardiovascular mortality were tracked for a minimum of 2 years.

Results: Six hundred seventy-four patients with severe aortic stenosis (age, 75±14 years; 63% male; aortic valve area, 0.38±0.14 cm²/m²; mean gradient, 46±18 mm Hg; left ventricular ejection fraction, 61.0±16.7%) were included. Scar was present in 51% (18% infarct pattern, 33% noninfarct). Management was surgical AVR (n=399) or transcatheter AVR (n=275). During follow-up (median, 3.6 years), 145 patients (21.5%) died (52 after surgical AVR, 93 after transcatheter AVR). In multivariable analysis, the factors independently associated with all-cause mortality were age (hazard ratio [HR], 1.50; 95% CI, 1.11-2.04; P=0.009, scaled by epochs of 10 years), Society of Thoracic Surgeons 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% versus 12.9%; P<0.001) and cardiovascular (15.0% versus 4.8%; P<0.001) mortality, regardless of intervention (transcatheter AVR, P=0.002; surgical AVR, P=0.026 [all-cause mortality]). Every 1% increase in left ventricular 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 aortic stenosis, late gadolinium enhancement on cardiovascular magnetic resonance was independently associated with mortality; its presence was associated with a 2-fold higher late mortality.

Keywords: aortic valve stenosis; magnetic resonance imaging; mortality; myocardium.

Figure 1.

Multi modality assessment of aortic stenosis (AS). Assessment of AS by transthoracic echocardiography (TTE; A–C) and cardiovascular magnetic resonance (D–F). A, Continuous Doppler trace across the aortic valve in the apical 5-chamber demonstrating hemodynamic parameters consistent with severe AS (peak velocity, 4.67 m/s; peak gradient, 87 mm Hg; mean gradient, 51 mm Hg). B, Short-axis TTE image of a severely calcified aortic valve. C, Parasternal long-axis image demonstrating left ventricular hypertrophy (#) and a calcified aortic valve (*). D, Four-chamber balanced steady-state free precession cine image demonstrating left ventricular hypertrophy; white dotted line demonstrates the axis of acquisition of the short axis (E and F). E, Late gadolinium enhancement (LGE) image in a midventricular short axis showing transmural LGE of a full-thickness myocardial infarct (arrow). F, LGE image in a midventricular short axis showing patchy nonischemia LGE in the mid inferolateral segment (arrow) and more subtle LGE in the inferoseptum and right ventricular insertion points.

Figure 2.

All-cause and cardiovascular mortality in severe aortic stenosis by late gadolinium enhancement (LGE) status. Kaplan-Meier (KM) survival plots showing all-cause (left) and cardiovascular (CV; right) mortality in all patients (A and B; n=674), patients treated with surgical aortic valve replacement (SAVR; C and D; n=399), and patients treated with transcatheter aortic valve replacement (TAVR; E and F; n=275), according to the presence or absence of LGE preoperatively. TAVI indicates transcatheter aortic valve implantation.

Figure 3.

All-cause mortality in severe aortic stenosis (AS) by late gadolinium enhancement (LGE) pattern. Kaplan-Meier (KM) survival plot showing all-cause mortality in all patients with severe AS (n=674) by pattern of late gadolinium enhancement (no LGE, infarct LGE, noninfarct LGE; both P<0.001). The plot summarizes 6-year follow-up data.