Blood Pressure Is a Major Modifiable Risk Factor Implicated in Pathogenesis of Intraplaque Hemorrhage: An In Vivo Magnetic Resonance Imaging Study.

OBJECTIVE: Effective prevention and management strategies of intraplaque hemorrhage (IPH) remain elusive because of our limited knowledge regarding its contributing factors. This hypothesis-generating study aimed to investigate associations between cardiovascular risk factors and IPH for improved understanding of the pathogenesis of IPH.

APPROACH AND RESULTS: Asymptomatic subjects with 16% to 79% stenosis on ultrasound underwent carotid magnetic resonance imaging using a large-coverage, 3-dimensional magnetic resonance imaging protocol. Individual plaques (maximum thickness >1.5 mm) in bilateral carotid arteries were identified, and presence of IPH was determined. From 80 subjects, 176 de novo plaques were measured, of which 38 (21.6%) contained IPH. Blood pressure (BP), primarily low diastolic BP, was associated with IPH in multivariate analysis adjusted for age, sex, and plaque size (odds ratio with 95% confidence interval per 10-mm Hg increase: 0.51 [0.30-0.88]), which was little changed after adjusting for antihypertensive use and systemic atherosclerosis. Antiplatelet use was associated with IPH in age and sex-adjusted models (P=0.018), for which a trend remained after considering plaque size and past medical history (odds ratio for aspirin alone versus none: 3.1 [0.66-14.8]; odds ratio for clopidogrel or dual therapy versus none: 5.3 [0.80-35.0]; P=0.083).

CONCLUSIONS: Low diastolic BP was independently associated with IPH, which was not attributed to treatment difference or BP changes from systemic atherosclerosis. Hemodynamic changes from lowering diastolic BP may be the pathophysiological link. Prospective serial studies are needed to assess whether BP and antiplatelet use are associated with the development of new or repeated IPH.