Blood Pressure in Asymptomatic Aortic Stenosis
Is there a link between blood pressure (BP) and outcomes in patients with asymptomatic mild and moderate aortic stenosis (AS)?
This was a post hoc analysis of data from the SEAS (Simvastatin Ezetimibe in Aortic Stenosis Study) trial, which enrolled patients with asymptomatic mild to moderate AS. Patients with diabetes, congestive heart failure (CHF), or atherosclerosis were not included in the trial. AS severity was defined by peak Doppler gradient with mild AS defined as a maximum gradient <3.0 m/s and moderate AS as maximum gradient 3.0-4.0 m/s. The primary outcome was all-cause mortality. Secondary outcomes of myocardial infarction (MI), CHF, stroke, or aortic valve replacement (AVR) were also tabulated. The original cohort included 1,873 patients, ages 45-85 years, of whom 1,767 (89%) had measurements adequate for inclusion in the study. BP was measured at baseline, 8 weeks, 24 weeks, and then twice annually. For purposes of data analysis, BP was defined as the average of all measurements from start to the last measurement. BP was categorized into four diastolic, systolic, and pulse pressure groups. Diastolic BP was characterized as <70 mm Hg, 70–79 mm Hg, 80–89 mm Hg, and ≥90 mm Hg. Systolic BP was characterized as <120 mm Hg, 120–139 mm Hg, 140–159 mm Hg, and ≥160 mm Hg.
Over a median follow-up of 4.3 years, 188 subjects died and 504 underwent AVR. There were 95 cardiovascular deaths, 66 strokes, 38 MIs, and 80 episodes of CHF. For the entire population, the lowest event rates were associated with systolic BP 120–139 mm Hg, diastolic BP 70–79 mm Hg, and pulse pressure 60–69 mm Hg. The risk association for systolic BP was U-shaped with a systolic BP of 120-139 mm Hg associated with the best survival. After adjusting for gender, age, history of hypertension, and severity of AS, all-cause mortality was highest for systolic BP ≥160 mm Hg (4.3 per 100 person-years) and lowest for systolic BP 120–139 mm Hg (2.0 per 100 person-years). Low diastolic BP conferred a low risk of stroke, but increased the risk of MI and CHF. AVR was not strongly associated with BP. A high diastolic BP was associated with all outcomes except AVR in patients with mild AS, whereas for moderate AS, low diastolic BP was associated with increased all-cause mortality and CHF.
In patients with asymptomatic mild and moderate AS, optimal BP appears to be 130–139 mm Hg systolic and 70–90 mm Hg diastolic.
It is generally presumed that the added pressure burden of hypertension will result in a greater tendency for adverse ventricular remodeling, systolic and diastolic dysfunction, and worsening symptoms in patients with AS. Limited data are available, however, to identify ideal BP targets in patients with AS. This study evaluated a large number of patients with asymptomatic mild and moderate AS who were free of atherosclerotic disease, diabetes, or CHF at baseline. For the general population, the authors describe a U-shaped curve of systolic and diastolic BP, suggesting that optimal blood pressure control in patients with mild to moderate AS would be a target of 130-139 mm Hg systolic. It should be emphasized that this is a post hoc analysis of a heterogeneous group of patients with respect to gender, age, and outcomes. The authors provide multiple subset analysis of the different outcomes of CHF, AVR, and stroke broken by age, gender, and BP categories, which demonstrate a complex relationship between BP control and various outcomes dependent on patient characteristics. As such, the recommendations above should be considered a general starting point for BP control in patients with asymptomatic mild to moderate AS. Based on these findings, overly aggressive BP control in patients with AS may be counterproductive.
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