Comparsion of central aortic pressure to brachial artery pressure in hypertensive patients on drug treatment: An observational study

BACKGROUND: High brachial blood pressure (BP) is an important cardiovascular risk factor. However major differences in central systolic BP can occur among people with similar brachial systolic BP. It is known that central aortic pressure responses to antihypertensive therapy can differ substantially from brachial BP responses, such that true treatment effects cannot be gauged from conventional brachial BP. OBJECTIVE: The purpose of this study was to examine if adequate control of brachial BP was concordant with central BP control in treated hypertensive subjects. METHODS: Non-invasive acquisition of brachial and central pressures and wave forms was obtained from 100 subjects with systemic arterial hypertension on drug therapy and 50 healthy individuals. After all necessary precautions according to the guidelines, brachial and central pressures and wave forms were measured 3 times at 5 min intervals using an upper arm cuff (AGEDIO K900 HDP Stolberg, Germany). The mean of the last two measurements of each was recorded as representative of brachial and central aortic pressures and wave forms. RESULTS: In 45 of 50 healthy subjects with normotension (41 male, 9 female, mean age 38 years), central systolic BP was <120 mmHg. Five healthy subjects (10%) had falsely normal brachial systolic BP, but raised central systolic BP. Out of 100 patients with known hypertension and on various anti-hypertensive drug combinations, 9 had uncontrolled hypertension (defined as brachial BP of >140/90 mmHg and central systolic BP > 120 mmHg). Ninety-one patients had controlled hypertension as estimated by brachial BP of whom, 37 patients had uncontrolled central BP (systolic BP > 120 mmHg). Thus, brachial BP estimation over-estimated control of hypertension in 41% patients (p < 0.01). Central systolic BP control was inadequate in 9 out of 41 patients (22%) on angiotensin receptor blocking therapy versus 27 out of 31 (87%) patients on beta-blocking therapy (p < 0.05). Thus, there was a marked mismatch with regard to control of hypertension between central and peripheral measurements. CONCLUSION: Central BP measurement provides important information on true prevalence of uncontrolled hypertension in the outpatient setting which is higher than current estimates from brachial BP measurement. Optimal BP control by central BP is far less than observed from peripheral pressure measurement. Residual cardiovascular risk despite adequate control of brachial BP can also be explained by the substantial frequency of uncontrolled hypertension as determined by the central BP in patients with apparently controlled hypertension. Both these conclusions have significant impact on prevalence of uncontrolled hypertension and its proper management. Further studies are required to confirm the current data and to provide evidence that treatment decisions based on measurements of central BP result in better outcomes.