Clinical Associations of Vascular Stiffness, Microvascular Dysfunction, and Prevalent Cardiovascular Disease in a Black Cohort: The Jackson Heart Study

Post-occlusive reactive hyperemia in habituated caffeine users: Effects of abstaining versus consuming typical doses

BACKGROUND

Post-occlusive reactive hyperemia (PORH) typically requires caffeine abstinence. For habitual users, it is unknown if abstinence affects PORH.

OBJECTIVE

Compare PORH after habitual users consume or abstain from caffeine.

METHODS

On separate visits (within-subject), PORH was measured in 30 participants without abstinence from typical caffeine doses (CAFF) and with abstinence (ABS). Measurements included baseline and peak hyperemic velocity, tissue saturation index slopes during ischemia (Slope 1) and following cuff deflation (Slope 2), resting arterial occlusion pressure (AOP), heart rate (HR), systolic (SBP), and diastolic (DBP) blood pressure. All variables were compared using Bayesian paired t-tests. BF10 = likelihood of alternative vs null. Results are mean±SD.

RESULTS

Comparing baseline velocity (cm/s) between CAFF (9.3±4.8) and ABS (7.5±4.9) yielded anecdotal evidence (BF10 = 1.0). Peak hyperemic velocity (cm/s) was similar (CAFF = 77.3±16.7; ABS = 77.6±19.0, BF10 = 0.20). For slopes (TSI% /s), CAFF Slope 1 = -0.11±0.04 and Slope 2 = 1.9±0.46 were similar (both BF10≤0.20) to ABS Slope 1 = -0.12±0.03 and Slope 2 = 1.8±0.42. SBP and DBP (mmHg) were both similar (CAFF SBP = 116.0±9.8, DBP = 69.6±5.8; ABS SBP = 115.5±10.7, DBP = 69.5±5.4; both BF10≤0.22). Comparing AOP (mmHg) (CAFF = 146.6±15.0; ABS = 143.0±16.4) yielded anecdotal evidence (BF10 = 0.46). HR (bpm) was similar (CAFF = 66.5±12.3; ABS = 66.9±13.0; BF10 = 0.20).

CONCLUSIONS

In habitual users, consuming or abstaining from typical caffeine doses does not appear to affect post-occlusive reactive hyperemia.

Application of a novel index for understanding vascular health following pharmacological intervention in a pre-clinical model of metabolic disease

While a thorough understanding of microvascular function in health and how it becomes compromised with progression of disease risk is critical for developing effective therapeutic interventions, our ability to accurately assess the beneficial impact of pharmacological interventions to improve outcomes is vital. Here we introduce a novel Vascular Health Index (VHI) that allows for simultaneous assessment of changes to vascular reactivity/endothelial function, vascular wall mechanics and microvessel density within cerebral and skeletal muscle vascular networks with progression of metabolic disease in obese Zucker rats (OZR); under control conditions and following pharmacological interventions of clinical relevance. Outcomes are compared to "healthy" conditions in lean Zucker rats. We detail the calculation of vascular health index, full assessments of validity, and describe progressive changes to vascular health index over the development of metabolic disease in obese Zucker rats. Further, we detail the improvement to cerebral and skeletal muscle vascular health index following chronic treatment of obese Zucker rats with anti-hypertensive (15%-52% for skeletal muscle vascular health index; 12%-48% for cerebral vascular health index; p < 0.05 for both), anti-dyslipidemic (13%-48% for skeletal muscle vascular health index; p < 0.05), anti-diabetic (12%-32% for cerebral vascular health index; p < 0.05) and anti-oxidant/inflammation (41%-64% for skeletal muscle vascular health index; 29%-42% for cerebral vascular health index; p < 0.05 for both) drugs. The results present the effectiveness of mechanistically diverse interventions to improve cerebral or skeletal muscle vascular health index in obese Zucker rats and provide insight into the superiority of some pharmacological agents despite similar effectiveness in terms of impact on intended targets. In addition, we demonstrate the utility of including a wider, more integrative approach to the study of microvasculopathy under settings of elevated disease risk and following pharmacological intervention. A major benefit of integrating vascular health index is an increased understanding of the development, timing and efficacy of interventions through greater insight into integrated microvascular function in combination with individual, higher resolution metrics.

Blood pressure response during treadmill exercise testing and the risk for future cardiovascular events and new-onset hypertension

OBJECTIVE

The physiologic response to exercise may provide valuable prognostic information. We investigated the association of blood pressure (BP) measurements during exercise stress testing (EST) with long-term risk of myocardial infarction, stroke or death (major adverse cardiovascular event, MACE), as well as the development of new-onset hypertension.

METHODS

A retrospective analysis of treadmill ESTs (years 2005-2019) performed by the Bruce protocol in patients aged 35-75 years without a history of cardiovascular disease (n = 14 792; 48% women). BP was documented at rest, submaximal exercise (Bruce stage-2), peak exercise and recovery (2 min). Association of SBP measures with study outcomes during median follow-up of 6.5 years was investigated.

RESULTS

Highest vs. lowest SBP quartile at rest (≥140 vs. <120 mmHg), submaximal-exercise (≥170 vs. <130 mmHg), peak-exercise (≥180 vs. ≤145 mmHg) and recovery (≥160 vs. <130 mmHg) was associated with an increase in the adjusted hazard ratio and 95% confidence interval (CI) for MACE: 1.53 (1.23-1.88), 1.33 (1.01-1.76), 1.30 (1.05-1.61), 1.35 (1.09-1.68), respectively. The association between SBP at submaximal exercise and recovery with MACE displayed a J-shaped pattern. Among nonhypertensive patients (n = 8529), excessive SBP response to peak exercise (≥190 mmHg in women and ≥210 mmHg in men) was an independent predictor of hypertension [hazard ratio (95% CI)]: 1.87 (1.41-2.48), as were SBPs during submaximal exercise [>160 vs. ≤130 mmHg: 2.44 (1.97-3.03)] and recovery [≥140 vs. ≤120 mmHg: 1.65 (1.37-1.98)].

CONCLUSION

BP measurement during rest, exercise and recovery phases of EST provides incremental prognostic information regarding long-term risk for cardiovascular events and the probability for developing hypertension.

Young black women demonstrate impaired microvascular but preserved macrovascular function compared to white women

NEW FINDINGS

What is the central question of this study? Is there a racial disparity in macrovascular and/or microvascular function between young black and white women? What is the main finding and its importance? Black women (BLW) demonstrated impaired microvascular function but similar macrovascular function compared to white women (WHW). These findings suggest an identifiable racial disparity in microvascular function between BLW and WHW as early as young adulthood. Microvascular dysfunction is predictive of future cardiovascular disease (CVD) and generally precedes the development of macrovascular dysfunction. Therefore, these findings also suggest that evaluating microvascular function and CVD risk in young, otherwise healthy BLW are important, as there are known racial disparities in CVD morbidity and mortality in black adults.

ABSTRACT

Black women (BLW) have a higher incidence of cardiovascular disease (CVD) morbidity and mortality compared to white women (WHW). Vascular dysfunction is a non-traditional risk factor for CVD and BLW demonstrate impaired vascular function when compared to WHW throughout the lifespan. Several previous studies assessed macrovascular and microvascular function in young BLW compared to WHW, but there has been no recent work exploring this disparity in young women using current, up-to-date methodologies. Therefore, the purpose of this study was to evaluate both macrovascular and microvascular function as assessed by haemodynamic responses to flow-mediated dilatation (FMD), following current FMD guidelines, in young adult BLW and WHW. We hypothesized that BLW would demonstrate attenuated macrovascular and microvascular responses to FMD compared to WHW. Macrovascular function was assessed as the percentage dilatation of the brachial artery following FMD occlusion-cuff release (FMD%). Microvascular function was assessed by total reactive hyperaemia area under the curve (RH-AUC), calculated as the cumulative increase in brachial artery blood flow above baseline following FMD occlusion-cuff release. Participants were tested in the morning hours during the early follicular phase of their menstrual cycle. Twenty-eight young, apparently healthy women completed the study: 17 WHW (23 ± 4 years) and 11 BLW (24 ± 5 years). FMD% was lower in BLW (WHW: 8.0 ± 1.6, BLW: 6.2 ± 2.4%; P = 0.02), but significance was abolished when FMD% was normalized for shear (WHW: 0.1230 ± 0.0388, BLW: 0.1132 ± 0.0405; P = 0.53). RH-AUC was lower in BLW (WHW: 438 ± 133, BLW: 268 ± 66 ml/min; P < 0.001). Young, otherwise healthy BLW demonstrated impaired microvascular function compared to WHW.

Clinical Associations of Vascular Stiffness, Microvascular Dysfunction, and Prevalent Cardiovascular Disease in a Black Cohort: The Jackson Heart Study

Background

Measures of vascular dysfunction are related to adverse cardiovascular disease (CVD) outcomes in non‐Hispanic, White populations; however, data from Black individuals are limited. We aimed to investigate the associations between novel hemodynamic measures and prevalent CVD in a sample of Black individuals.

Methods and Results

Among older Black participants of the Jackson Heart Study, we assessed noninvasive vascular hemodynamic measures using arterial tonometry and Doppler ultrasound. We assessed 5 measures of aortic stiffness and wave reflection (carotid‐femoral pulse wave velocity, pulse wave velocity ratio, forward pressure wave amplitude, central pulse pressure, and augmentation index), and 2 measures of microvascular function (baseline and hyperemic brachial flow velocity). Using multivariable logistic regression models, we examined the relations between vascular hemodynamic measures and prevalent CVD. In models adjusted for traditional CVD risk factors, higher carotid‐femoral pulse wave velocity (odds ratio [OR],1.25; 95% CI, 1.01–1.55; P=0.04), lower augmentation index (OR, 0.84; 95% CI, 0.70–0.99; P=0.05), and lower hyperemic brachial flow velocity (OR, 0.77; 95% CI, 0.65–0.90; P=0.001) were associated with higher odds of CVD. After further adjustment for hypertension treatment, lower augmentation index (OR, 0.84; 95% CI, 0.70–0.99; P=0.04) and hyperemic brachial flow velocity (OR, 0.79; 95% CI, 0.67–0.94; P=0.006), but not carotid‐femoral pulse wave velocity (OR, 1.23; 95% CI, 0.99–1.051; P=0.06), were associated with higher odds of CVD.

Conclusions

In a sample of older Black individuals, more severe microvascular damage and aortic stiffness were associated with prevalent CVD. Further research on hemodynamic mechanisms that contribute to cardiovascular risk among older Black individuals is merited.