Body Surface Area and Prevalence of Severe Aortic Stenosis
Body Surface Area and Prevalence of Severe Aortic Stenosis
Data from two distinct study populations are presented. First, we identified 2843 consecutive patients investigated at the echocardiographic laboratory of the Heart Centre Bad Krozingen between January 1998 and December 2010 demonstrating normal left ventricular function and a jet velocity of ≥2.5 m/s. Patients with a moderate or severe mitral or aortic regurgitation, a mean pressure gradient <10 mm Hg or incomplete data were excluded. Normal left ventricular function was defined as normal global systolic left ventricular function with fractional shortening ≥30% without regional wall motion abnormalities.
The second cohort was recruited from the prospective SEAS study (NCT00092677), which enrolled 1873 patients with asymptomatic aortic stenosis, defined by echocardiography at local study centres as aortic valve thickening and transaortic Doppler jet velocity ≥2.5 and ≤4.0 m/s. Patients were randomised from January 2001 to February 2004 to at least 4-year placebo-controlled combined treatment with ezetimibe 10 mg/day and simvastatin 40 mg/day. Patients with coronary heart disease, heart failure, diabetes, history of stroke or peripheral vascular disease, clinically significant mitral valve disease, severe or predominant aortic regurgitation, rheumatic valvular disease, aortic valve prosthesis or renal insufficiency, and patients already on lipid-lowering therapy or having an indication for lipid lowering according to guidelines were excluded. The original SEAS study showed no difference in major cardiovascular events between treatment and placebo group but a significant reduction in ischaemic events in patients treated with ezetimibe/simvastatin. The present study population comprises 1525 (81.4%) of the 1873 patients recruited in the SEAS trial with an ejection fraction ≥55% in whom a detailed echocardiographic assessment by the core laboratory at baseline was available.
Echocardiography was performed following the guidelines for the clinical application of echocardiography and has been described in detail elsewhere. Severe aortic stenosis was defined according to current guidelines by an AVA<1.0 cm and an AVAindex<0.6 cm/m. The velocity ratio (VR) as a body size independent measure of aortic stenosis severity was calculated by the velocity time integral (VTI) of pulsed wave Doppler in the left ventricular outflow tract divided by the VTI of continuous Doppler through the aortic valve. Anthropometric data (height and weight) were recorded electronically at the time of echocardiography. BSA was calculated from the Mosteller formula:
. Body mass index (BMI) was calculated as BMI = weight/height . The primary end point of the outcome analysis of the present study was aortic valve related events (defined as aortic valve replacement, congestive heart failure due to aortic stenosis, or death from cardiovascular causes); the secondary end point was cardiovascular death. All end points had been adjudicated with a predefined end point protocol by an end point committee blinded for study conduct and results in the original SEAS study. All statistics were performed using SPSS V.15.0 with continuous variables presented as mean±SD and categorical variables as percentages. Percentages were compared with the use of the Pearson χ test. Receiver operating characteristic (ROC) curves were constructed to assess the sensitivity and specificity of parameters of AVA and an AVA index and to compare their ability to predict aortic valve events or cardiovascular death. The comparison of areas under the ROC curves (AUC) was performed as recommended by DeLong et al. The Kaplan–Meier method was used to assess event-free survival with differences checked by means of the log-rank test. All testing was two-tailed, and p values of less than 0.05 were considered to indicate statistical significance.
Patients and Methods
Data from two distinct study populations are presented. First, we identified 2843 consecutive patients investigated at the echocardiographic laboratory of the Heart Centre Bad Krozingen between January 1998 and December 2010 demonstrating normal left ventricular function and a jet velocity of ≥2.5 m/s. Patients with a moderate or severe mitral or aortic regurgitation, a mean pressure gradient <10 mm Hg or incomplete data were excluded. Normal left ventricular function was defined as normal global systolic left ventricular function with fractional shortening ≥30% without regional wall motion abnormalities.
The second cohort was recruited from the prospective SEAS study (NCT00092677), which enrolled 1873 patients with asymptomatic aortic stenosis, defined by echocardiography at local study centres as aortic valve thickening and transaortic Doppler jet velocity ≥2.5 and ≤4.0 m/s. Patients were randomised from January 2001 to February 2004 to at least 4-year placebo-controlled combined treatment with ezetimibe 10 mg/day and simvastatin 40 mg/day. Patients with coronary heart disease, heart failure, diabetes, history of stroke or peripheral vascular disease, clinically significant mitral valve disease, severe or predominant aortic regurgitation, rheumatic valvular disease, aortic valve prosthesis or renal insufficiency, and patients already on lipid-lowering therapy or having an indication for lipid lowering according to guidelines were excluded. The original SEAS study showed no difference in major cardiovascular events between treatment and placebo group but a significant reduction in ischaemic events in patients treated with ezetimibe/simvastatin. The present study population comprises 1525 (81.4%) of the 1873 patients recruited in the SEAS trial with an ejection fraction ≥55% in whom a detailed echocardiographic assessment by the core laboratory at baseline was available.
Echocardiography was performed following the guidelines for the clinical application of echocardiography and has been described in detail elsewhere. Severe aortic stenosis was defined according to current guidelines by an AVA<1.0 cm and an AVAindex<0.6 cm/m. The velocity ratio (VR) as a body size independent measure of aortic stenosis severity was calculated by the velocity time integral (VTI) of pulsed wave Doppler in the left ventricular outflow tract divided by the VTI of continuous Doppler through the aortic valve. Anthropometric data (height and weight) were recorded electronically at the time of echocardiography. BSA was calculated from the Mosteller formula:
. Body mass index (BMI) was calculated as BMI = weight/height . The primary end point of the outcome analysis of the present study was aortic valve related events (defined as aortic valve replacement, congestive heart failure due to aortic stenosis, or death from cardiovascular causes); the secondary end point was cardiovascular death. All end points had been adjudicated with a predefined end point protocol by an end point committee blinded for study conduct and results in the original SEAS study. All statistics were performed using SPSS V.15.0 with continuous variables presented as mean±SD and categorical variables as percentages. Percentages were compared with the use of the Pearson χ test. Receiver operating characteristic (ROC) curves were constructed to assess the sensitivity and specificity of parameters of AVA and an AVA index and to compare their ability to predict aortic valve events or cardiovascular death. The comparison of areas under the ROC curves (AUC) was performed as recommended by DeLong et al. The Kaplan–Meier method was used to assess event-free survival with differences checked by means of the log-rank test. All testing was two-tailed, and p values of less than 0.05 were considered to indicate statistical significance.
