Abstract
IntroductionHypertension (HTN) is the leading cause of cardiovascular mortality and morbidity. Invasive intra-aortic pressures are the gold standard for accurate blood pressure (BP) measurement and may be a better predictor of adverse cardiovascular(CV) outcomes than pressure measured in the brachial artery. However, in clinical practice, HTN management is guided by brachial cuff BP although its accuracy has now been questioned in recent years.HypothesisWe hypothesized that cuff-based brachial BP measurements may not correctly estimate intra-aortic BP with implications for correct management of HTN.MethodsIn this study, invasive intra-aortic and brachial cuff pressures were recorded in some 3000 patients undergoing coronary angiography( mean age 58.6±28, 23% female) between the years 2010 and 2016, at King Abdul Aziz Cardiac Centre, King Abdul Aziz Medical City, Riyadh, Saudi Arabia. Clinical and angiographic data were collected from electronic medical records (Apollo Lx®) .ResultsCuff brachial BP underestimated intra-aortic systolic BP (–6.2 mm Hg; 95% CI–7.2 to -5.4 mm Hg; p < 0.0001), but overestimated intra-aortic diastolic BP (2.5 mm Hg; 95% CI1.5 to 3.8 mm Hg; p < 0.001). The discrepancy between intra-aortic and brachial systolic BP was significantly higher in women than men ( -15 mm Hg; 95% CI-14 to -17 mm Hg vs. -3.9 mm Hg; 95% CI-2.8 to -4.1 mm Hg, p<0.0001). Intra-aortic diastolic BP was overestimated by cuff BP in men (0.9 mm Hg; 95% CI; 0.74 to 1.26, p<0.0.001) but underestimated in women ( -3.6 mm Hg; 95% CI-3 to -4 mm Hg, p<0.0001). While the cuff brachial BP correctly estimated intra-aortic systolic BP in subjects <50 yr-olds ( 0.13 mm Hg; 95% CI-0.57 to 0.85 mm Hg, p=0.68), there was a large discrepancy in >50 yr-olds ( -8.6 mm Hg; 95% CI-8.1 to -9.5 mm Hg, p<0.0001). Concordance between BP classifications with intra-aortic BP as reference using JNC8 cuff BP criteria (normal, pre-HTN, and HTN stages 1 and 2) was 81%, 60%, 64%, and 30%, respectively and with ACC/AHA recommended cut-offs (normal, elevated, Stage I and Stage II), 80%, 77%, 45% and 35% respectively.ConclusionsIn conclusion, cuff BP underestimates intra-aortic systolic BP, particularly in women, older subjects and at higher BPs, with implications for management of HTN. This calls for stronger accuracy standards for cuff BP measuring devices and a call for validation of non-invasive aortic BP measurements in clinical practice to improve CV risk management.