Residual compromised myocardial contractile reserve after valve replacement for aortic stenosis

OBJECTIVE: Despite recovery of left ventricular (LV) function and morphology after aortic valve replacement (AVR) for aortic stenosis (AS), its relationship with exercise capacity remains unknown. Twenty-one AVR patients (age 61 ± 12 years, 14 male) with normal ejection fraction (EF, 64 ± 7%) and 21 age- and sex-matched controls (57 ± 9 years, 10 male, EF 68 ± 8%) were studied. METHODS AND RESULTS: All subjects performed semi-supine bicycle exercise and speckle tracking echocardiography (STE) study. Peak oxygen consumption (pVO(2)) was collected during semi-supine bicycle exercise. Systolic (GLSRs) and early diastolic (GLSRe) longitudinal strain rate using STE and Doppler echocardiographic parameters were measured at rest, submaximal, peak exercise, and 4 min after exercise. The two groups had comparable resting echocardiographic measurements. At peak exercise, pVO(2) was lower in patients than controls (18.5 ± 4.5 vs. 22.1 ± 4.3 L/min/kg, P < 0.05). GLSRs (0.98 ± 0.28 vs. 1.55 ± 0.30 1/s, P < 0.001), septal Sm (7.9 ± 1.4 vs. 11.1 ± 2.3 cm/s, P < 0.001) and their changes between rest and peak exercise (ΔGLSRs: 0.16 ± 0.33 vs. 0.68 ± 0.27 1/s, P < 0.001; ΔSm 2.29 ± 2.23 vs. 4.63 ± 2.29 cm/s, P < 0.01) were significantly lower in patients than controls. There was no correlation between pVO(2) and any echocardiographic measurements in controls. In patients, pVO(2) correlated with peak exercise GLSRs (r = 0.60, P = 0.0007), septal Sm (r = 0.65, P = 0.002), and Em (r = 0.57, P = 0.009). In a multivariate model, peak exercise GLSRs (β = 7.18, P = 0.03) was the only independent predictor of pVO(2) in the patients group. CONCLUSION: Exercise capacity is subnormal after AVR for AS, irrespective of normal LVEF suggesting residual compromised myocardial functional reserve.