Risk Stratification by Cross-Classification of Central and Brachial Systolic Blood Pressure

Abstract

Background: Whether cardiovascular risk is more tightly associated with central (cSBP) than brachial (bSBP) systolic pressure remains debated, because of their close correlation and uncertain thresholds to differentiate cSBP into normotension versus hypertension. Methods: In a person-level meta-analysis of the International Database of Central Arterial Properties for Risk Stratification (n=5576; 54.1% women; mean age 54.2 years), outcome-driven thresholds for cSBP were determined and whether the cross-classification of cSBP and bSBP improved risk stratification was explored. cSBP was tonometrically estimated from the radial pulse wave using SphygmoCor software. Results: Over 4.1 years (median), 255 composite cardiovascular end points occurred. In multivariable bootstrapped analyses, cSBP thresholds (in mm Hg) of 110.5 (95% CI, 109.1–111.8), 120.2 (119.4–121.0), 130.0 (129.6–130.3), and 149.5 (148.4–150.5) generated 5-year cardiovascular risks equivalent to the American College of Cardiology/American Heart Association bSBP thresholds of 120, 130, 140, and 160. Applying 120/130 mm Hg as cSBP/bSBP thresholds delineated concordant central and brachial normotension (43.1%) and hypertension (48.2%) versus isolated brachial hypertension (5.0%) and isolated central hypertension (3.7%). With concordant normotension as reference, the multivariable hazard ratios for the cardiovascular end point were 1.30 (95% CI, 0.58–2.94) for isolated brachial hypertension, 2.28 (1.21–4.30) for isolated central hypertension, and 2.02 (1.41–2.91) for concordant hypertension. The increased cardiovascular risk associated with isolated central and concordant hypertension was paralleled by cerebrovascular end points with hazard ratios of 3.71 (1.37–10.06) and 2.60 (1.35–5.00), respectively. Conclusions: Irrespective of the brachial blood pressure status, central hypertension increased cardiovascular and cerebrovascular risk indicating the importance of controlling central hypertension.

Central hypertension is a non‐negligible cardiovascular risk factor

“… According to ref. [ 14 ], the thresholds of central systolic blood pressure yielded similar 5‐year risk of a composite cardiovascular event as the corresponding brachial values. Diastolic blood pressure is similar throughout the arterial tree.…”

“… 14 The concordant normotension, concordant hypertension, isolated brachial hypertension, and isolated central hypertension, respectively, accounted for 43.1%, 48.2%, 5.0%, and 3.7% of the 5576 study participants. 14 The mean age of the corresponding patients was 47.8, 60.5, 47.3, and 57.3 years, respectively. In elderly, pressure amplification from central to peripheral arteries decreases and the difference between central and brachial BP becomes small, 26 therefore the prevalence of isolated brachial or isolated central hypertension may vary with age.…”

“…Based on the central and brachial BP status, patients could be cross‐classified as concordant or discordant normotensive or hypertensive. 11 , 12 , 13 Emerging evidence indicated that such cross‐classification might improve risk stratification and have its clinical significance, 14 which shed some light on the application of central BP measurement. In this article, we aim to briefly review the prognostic value of central versus brachial BP in prospective population studies and discuss about the diagnosis and treatment of central hypertension in individual patients.…”

“… 24 Along similar lines, the IDCARS collaboration determined the thresholds by considering both fatal and nonfatal endpoints in multiethnic populations. 14 Central systolic BP estimated by the type‐I device (SphygmoCor) of 110.4 (95% CI, 109.0–111.9), 120.2 (119.3–121.0), 129.9 (129.5–130.3), and 149.4 (148.2–150.6) mmHg yielded similar 5‐year risk of composite cardiovascular events as the brachial systolic BP of 120, 130, 140, and 160 mmHg, respectively. 14 Taken the results of 2 outcome‐based studies together, 14 , 24 the rounded thresholds for central systolic BP were approximately 10 mmHg lower than their brachial counterparts, and those for diastolic BPs were similar between the central and brachial arterial sites (Table 1 ).…”

“… 14 Central systolic BP estimated by the type‐I device (SphygmoCor) of 110.4 (95% CI, 109.0–111.9), 120.2 (119.3–121.0), 129.9 (129.5–130.3), and 149.4 (148.2–150.6) mmHg yielded similar 5‐year risk of composite cardiovascular events as the brachial systolic BP of 120, 130, 140, and 160 mmHg, respectively. 14 Taken the results of 2 outcome‐based studies together, 14 , 24 the rounded thresholds for central systolic BP were approximately 10 mmHg lower than their brachial counterparts, and those for diastolic BPs were similar between the central and brachial arterial sites (Table 1 ). Nonetheless, it is important to note that the proposed thresholds may only be applied to the central BP estimated by the type‐I device, especially the SphygmoCor system, and need to be tested in future studies using various devices.…”