2.2: Transfer Function-Derived Central Pressure and Cardiovascular Events: The Framingham Heart Study

Abstract

Relations between central versus brachial blood pressure and major cardiovascular disease (CVD) events remain controversial. Central measures derived using radial tonometry and a generalized transfer function as implemented using the SphygmoCor device may better predict CVD risk compared to central pressures from carotid tonometry. We used proportional hazards models to examine relations of augmentation index, central systolic and pulse pressure, and central-to-peripheral pulse pressure amplification obtained using the Sphygmocor algorithm to first-onset major CVD events in 2183 participants (mean age 62 years, 58% women) in the Framingham Heart Study. During median follow-up of 7.8 (range 0.2 to 8.9) years, 149 participants (6.8%) had an incident event. Augmentation index (P = 0.6), central systolic pressure (P = 0.20), central pulse pressure (P = 0.24) and pulse pressure amplification (P = 0.15) were not related to outcomes in models that adjusted for age, sex, clinic systolic blood pressure, use of antihypertensive therapy, total and high density lipoprotein cholesterol concentrations, smoking, and presence of diabetes. When models were repeated using supine oscillometric systolic pressure recorded at the time of tonometry and excluding cases with tonometry pulse height variations >5%, pulse diastolic variation >5%, pulse shape variation >4% or an operator index <80, as recommended by SphygmoCor documentation (N = 1262, 64 events), central pulse pressure estimated using the SphygmoCor algorithm was inversely associated with events (HR=0.64, confidence limits 0.42 to 0.98; P = 0.04). After considering standard risk factors including brachial systolic pressure, higher central pressure derived using radial artery tonometry and a generalized transfer function was not associated with higher CVD risk.