Symptoms in Patients With Severe Aortic Stenosis and Preserved Left Ventricular Ejection Fraction: Is It All About Diastole?
Although it has been ≈50 years since Ross and Braunwald1 reported the malignant natural history of aortic stenosis (AS) after the onset of angina, syncope, or heart failure, the pathophysiologic underpinnings of these classic symptoms remain incompletely delineated. We appreciate that angina may occur in the absence of epicardial coronary disease with both increased demand and impaired supply, contributing to imbalance of the supply–demand relationship. Exertional syncope reflecting the inability to maintain cerebral perfusion is attributed to an inability to increase cardiac output in combination with, at times, paradoxically reduced systemic vascular resistance. Although we attribute the low-output symptoms of heart failure to the same inability to increase cardiac output, we still have an incomplete understanding of the changes that restrict stroke volume augmentation. Similarly, although the dyspnea of heart failure is typically linked to elevated pulmonary capillary pressures, which of the multiple pathways leading to elevated pulmonary pressures is/are operative in the symptomatic patient with AS? Although afterload mismatch and attendant left ventricular (LV) systolic dysfunction provide a substrate for symptoms in some patients, understanding the basis for symptoms in patients with preserved LV ejection fraction (EF) is particularly challenging because measures of AS severity alone predict the onset of but correlate imperfectly with the presence of symptoms.2
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In this issue of Circulation: Cardiovascular Imaging, Dahl et al3 provide hypothesis-generating data that argue an important role for LV remodeling and diastolic dysfunction in the pathogenesis of symptoms in patients AS and preserved (≥50%) LVEF. They compared echocardiographic parameters in 139 asymptomatic patients assessed in an outpatient clinic and 99 symptomatic patients referred for surgical intervention. Although the symptomatic patients were surprisingly younger, had less atrial fibrillation, hypertension, and chronic lung disease than did the asymptomatic cohort, higher LV mass index and …