Abstract
BackgroundAortic stenosis (AS) is a progressive disease in which left ventricular (LV) diastolic dysfunction is common. However, the association between diastolic dysfunction and right ventricular (RV) loading conditions and function has not been investigated in asymptomatic AS patients.Methods and findingsA total of 41 patients underwent right heart catheterization and simultaneous echocardiography at rest and during maximal supine exercise, stratified according to resting diastolic function. Cardiac chamber size and morphology was assessed using cardiac magnetic resonance imaging (cMRI). RV stroke work index, pulmonary artery (PA) compliance, PA elastance, PA pulsatility index, and right atrial pressure (RAP) were calculated at rest and maximal exercise. Ten patients (24%) had normal LV filling pattern, 20 patients (49%) had grade 1, and 11 patients (27%) had grade 2 diastolic dysfunction. Compared to patients with normal diastolic filling pattern, patients with diastolic dysfunction had lower RV end-diastolic volume (66 ± 11 ml/m2 vs. 79 ± 15 ml/m2, p = 0.02) and end-systolic volume (25 ± 7 ml/m2 vs. 32 ± 9 ml/m2, p = 0.04). An increase in mean RAP to ≥15 mmHg following exercise was not seen in patients with normal LV filling, compared to 4 patients (20%) with mild and 7 patients (63%) with moderate diastolic dysfunction (p = 0.003). PA pressure and PA elastance was increased in grade 2 diastolic dysfunction and correlated with RV volume and maximal oxygen consumption (r = -0.71, p < 0.001).ConclusionsModerate diastolic dysfunction is associated with increased RV afterload (elastance), which is compensated at rest, but is associated with increased RAP and inversely related to maximal oxygen consumption during maximal exercise.
Highlights
Calcified aortic stenosis (AS) is a chronic, slowly progressing disorder where pressure overload can lead to heart failure symptoms warranting aortic valve replacement [1]
Moderate diastolic dysfunction is associated with increased right ventricle (RV) afterload, which is compensated at rest, but is associated with increased right atrial pressure (RAP) and inversely related to maximal oxygen consumption during maximal exercise
Patients were classified into 3 groups according to left ventricular (LV) diastolic filling pattern: 10 patients (24%) had normal diastolic filling pattern, 20 patients (49%) had grade 1 diastolic dysfunction, and 11 patients (27%) had grade 2 diastolic dysfunction
Summary
Calcified aortic stenosis (AS) is a chronic, slowly progressing disorder where pressure overload can lead to heart failure symptoms warranting aortic valve replacement [1]. Some patients remain asymptomatic for years with gradual adaptation to pressure overload. The filling pressure increases during diastolic dysfunction especially during exertion, thereby exposing the right ventricle (RV) to increased afterload through the pulmonary vascular bed [5]. Prior hemodynamic studies have shown that loading conditions on the left side of the heart inevitably affects RV diastolic properties and pressure, possibly through ventricular interdependence [6]. Previous studies have demonstrated that exercise in symptomatic as well as asymptomatic patients with AS inflicts severe post-capillary pulmonary artery hypertension, exposing the RV to increased afterload [7, 8]. The association between diastolic dysfunction and right ventricular (RV) loading conditions and function has not been investigated in asymptomatic AS patients
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