Silent Ischemia Is Associated With Subclinical Atherosclerosis in African Males: The Sympathetic Activity and Ambulatory Blood Pressure in Africans Study

Abstract

Silent myocardial ischemia is a predictor of subclinical atherosclerosis driven by increased cardiovascular risk markers, although still unknown in Africans. The aim of this study was to assess if cardiovascular risk markers will be associated with subclinical atherosclerosis. African men were stratified into (i) 24-hour silent ischemia (SI, n = 38) and (ii) without (nSI, n = 40) groups. Ambulatory blood pressure (BP), SI, 12-lead resting electrocardiogram, ultrasound carotid intima-media thickness (CIMT) measurements, and fasting blood samples were obtained. Above-normal cardiovascular risk markers, that is, glucose level, heart rate, BP, and CIMT, were evident in men with SI. Hypertension prevalence was 89% in the African SI men as opposed to 64% in the nSI men. Regression analyses revealed that only SI events in SI men explained 35% (95% confidence interval [CI]: 0.22;0.52) of the variance in CIMT, while in all African men it explained 29% (95% CI: 0.19;0.39). In conclusion, SI was associated with structural vascular disease in African men. This could imply that SI is not necessarily driven by hypertension in African men but through other possible mechanisms such as increased sympathetic nervous system activity.

Troponin T release is associated with silent myocardial ischaemia in black men: The SABPA Study

“…Also, the black participants had significantly more SMI events than the white participants, although no ethnic difference was evident in the total duration and maximum duration of SMI events. Associations between the prevalence of SMI and CVD have been linked with higher 24 h BP values in people with hypertension, 4,18 and the higher number of SMI events may be detrimental to the higher 24 h BP values.…”

“…We previously demonstrated a higher incidence of SMI in black men. 4 However, the higher incidence and maximum duration of one SMI event or the increased intensity of all SMI events over 24 h in black men may be the driving force for injury of the myocardium with lower hs-cTnT cut-points and compensatory systolic BP increases to alleviate myocardial ischaemia. Limitations to this study include the small sample size and the cross-sectional design, which cannot infer causality.…”

“…Silent myocardial ischaemia (SMI) contributes to the total ischaemic burden in people with coronary artery disease. [1][2][3] It is more evident in black people from South Africa than in the white population 4 and occurs more often in people with hypertension resulting from a reduced vascular supply and increased cardiac demand. 5,6 High sensitivity cardiac troponin T (hs-cTnT), which is often measured in primary myocardial ischemia [7][8][9] and minor myocardial injury, 10 may be useful in detecting chronic subclinical myocardial damage before the development of hypertension.…”