From short-term blood pressure variability to atherosclerosis: Relative roles of vascular stiffness and endothelial dysfunction

Both arterial blood pressure (BP) average levels and short-term BP variability (BPV) relate to hypertension-mediated organ damage, in particular increased carotid artery intima-media thickness (IMT) and carotid-femoral pulse wave velocity (PWV). Endothelial dysfunction possibly mediates such damage. The authors aimed at further investigating such role in hypertensive patients. In 189 recently diagnosed, untreated hypertensive patients the authors evaluated, in a cross-sectional design, the relationships of BP average levels and short-term systolic (S) BPV (standard deviation of awake SBP or of 24-hour-weighted SBP) with IMT and PWV, and how much these relationships are explained by endothelial function parameters-brachial artery flow-mediated dilation (FMD) and digital reactive hyperemia index (RHI). Multivariable models assessed the strength of these relationships to derive a plausible pathogenetic sequence. Both average SBP values and our measures of SBPV were significantly related to IMT (24-hour mean SBP: r = .156, P = .034; 24-hour-weighted SBPV: r = .157, P = .033) and to PWV (24-hour mean SBP: r = .179, P = .015; 24-hour-weighted SBPV: r = .175; P = .018), but only poorly related to FMD or RHI (P > .05 for all). At univariable regression analysis, FMD and RHI were both related to IMT, (P < .001), but not to PWV. When FMD and RHI were added to average SBP and SBPV parameters in a multivariable model, both significantly (P < .005) contributed to predict IMT, but not PWV. Thus, endothelial dysfunction relates to IMT independently of BP parameters, but appears to play a minor role in the association between BP variability-related variables and arterial stiffening.

Genetic determinants of cognitive responses to caffeine drinking identified from a double-blind, randomized, controlled trial

The widely observed between-subject variability in cognitive responses to coffee may have a genetic basis. We evaluated cognitive responses to caffeine throughout three complex cognitive tasks assessing different subdomains of attention, namely Alerting and Orienting (Categorical Search Task) and Executive Control (Stroop Task and Eriksen Flanker Task). We explored whether they are influenced by gene variants affecting adenosine metabolism or catecholamine receptors. We recruited 106 healthy male subjects who were administered, in a double-blind design, 40mL of either a decaffeinated coffee preparation plus 3mg/kg caffeine (caf) or the corresponding vehicle (decaf). The protocol was repeated 24h later with the alternative preparation. Cognitive tasks were performed between 30min and 2h after caf or decaf administration. Each subject underwent ambulatory blood pressure monitoring for 2h. Blood samples were collected for genetic evaluations and for plasma caffeine and catecholamines measures. We found a significant reduction of reaction times in two of the cognitive tasks (Categorical Search Task and Stroop Task) after caf compared with decaf, indicating that caffeine, on average, improved the attention level in the domains under investigation. We also found, however, a great inter-individual variability in the cognitive performance responses to caffeine. In exploring genetic sources for such variability, we found a relation between polymorphisms of adenosine A2A and the caffeine effects on the attentional domains of Orienting and Executive control. In conclusion, variability in the attentional response to coffee may be partly explained by genetic polymorphisms of adenosine and adrenergic receptors.

Cardiovascular morbidity and mortality related to orthostatic hypotension: a meta-analysis of prospective observational studies

BACKGROUND

Whether orthostatic hypotension (OH) is a risk factor for cardiovascular morbidity and death is uncertain. Currently available evidence derives from non-homogeneous and partly ambiguous studies.

OBJECTIVE

We aimed at assessing the relationship between OH and death or major adverse cardiac and cerebrovascular events (MACCEs) by integrating results of previous studies.

METHODS

We performed a meta-analysis of prospective observational studies reporting on the association between prevalent OH, mortality, and incident MACCE, published from 1966 through 2013. Mantel-Haenszel pooled estimates of relative risk (RR) and 95% confidence intervals (CIs) for all-cause death were assessed as the primary endpoint at the longest follow-up; incident coronary heart disease (CHD), heart failure (HF), and stroke were assessed as secondary endpoints. We also performed post hoc subgroup analyses stratified by age and a meta-regression analysis.

RESULTS

We identified a total of 13 studies, including an overall population of 121 913 patients, with a median follow-up of 6 years. Compared with the absence of OH, the occurrence of OH was associated with a significantly increased risk of all-cause death (RR 1.50; 95% CI 1.24-1.81), incident CHD (RR 1.41; 95% CI 1.22-1.63), HF (RR 2.25; 95% CI 1.52-3.33), and stroke (RR 1.64; 95% CI 1.13-2.37). When analysed according to age, pooled estimates of RR (95% CI) for all-cause death were 1.78 (1.25-2.52) for patients <65 years old, and 1.26 (0.99-1.62) in the older subgroup.

CONCLUSION

Orthostatic hypotension is associated with a significantly increased risk of all-cause death, incident CHD, HF, and stroke.

Genetic determinants of blood pressure responses to caffeine drinking

BACKGROUND

The widely observed between-subject variability in cardiovascular responses to coffee may have a genetic basis.

OBJECTIVE

We evaluated acute blood pressure (BP) responses to caffeine and explored whether they are influenced by candidate gene variants affecting caffeine metabolism (for cytochrome P450 1A2), adenosine metabolism (for adenosine receptor and AMP deaminase), or catecholamine receptors.

METHODS

We recruited 110 healthy male habitual moderate coffee drinkers who refrained from drinking coffee on the day preceding the study. Each subject underwent ambulatory BP monitoring at 6-min intervals for 2 h. Each participant was administered, in a double-blind design, 40 mL of either a decaffeinated coffee preparation plus 3 mg caffeine/kg (caf) or the corresponding vehicle (decaf). The protocol was repeated 24 h later with the alternative preparation. Blood samples were collected for genetic and plasma caffeine and catecholamine evaluations.

RESULTS

Compared with decaf, caf was associated with a mean (± SD) significant increase in systolic BP of 4 ± 12 mm Hg and in diastolic BP of 3 ± 10 mm Hg (P < 0.001 for both). Plasma caffeine and adrenaline increased after caf, but not after decaf. Of 11 gene polymorphisms analyzed, a relation was observed between the ADORA2A TT variant and the change in SBP peak and between the ADRA2B I variant and the changes in both SBP mean and peak; mean peak change in SBP; these variants were associated with increased SBP responses to caf.

CONCLUSIONS

Variability in the acute BP response to coffee may be partly explained by genetic polymorphisms of the adenosine A2A receptors and α(2)-adrenergic receptors. This trial is registered at clinicaltrials.gov as NCT01330680.

Effects of dual renin-angiotensin system blockade on proteinuria in a hypertensive black African HIV-infected patient

Case study

Defective recovery of QT dispersion predicts late cardiac mortality after percutaneous coronary intervention

BACKGROUND

It has been suggested that corrected QT dispersion (cQTD) provides a measure of repolarisation inhomogeneity; however, the existence of a relationship between cQTD and cardiac outcomes is controversial.

OBJECTIVE

To assess whether changes in cQTD following percutaneous coronary intervention (PCI) predict long-term survival.

DESIGN

Prospective observational study.

SETTING

Single tertiary care centre. Main outcome measures Cardiac mortality.

PATIENTS

612 patients had a 12-lead ECG recorded before and 6 h after PCI, and were followed-up for 49 ± 10 months.

RESULTS

PCI was associated with a significant overall reduction of cQTD at 6 h versus baseline (p < 0.001); a reduction in cQTD occurred in 343 patients (56%). During the follow-up, 46 deaths (7.5%) were recorded, 21 of which for non-cardiac and 25 for cardiac causes. At Cox regression analysis, a reduced ΔcQTD (cQTD baseline - 6 h) was an independent predictor of cardiac mortality (HR = 1.497; 95% CI 1.081 to 2.075 for each 20 ms decrease; p = 0.015), together with age (HR = 1.672; 95% CI 1.039 to 2.691 per 10 years increase; p = 0.034), diabetes (HR = 2.622; 95% CI 1.112 to 6.184; p=0.028), peak CK-MB (HR = 1.798; 95% CI 1.063 to 3.039 per each unit increase over normal level; p = 0.029), three-vessel coronary artery disease (HR=3.626; 95% CI 1.079 to 12.187; p = 0.037) and the number of treated lesions (HR=2.066; 95% CI 1.208 to 3.532; p = 0.008). Patients in the lowest tertile of ΔcQTD and having a post-procedural increase of CK-MB had a considerably higher cardiac mortality than the remaining population (14.6 vs 2.4%, p < 0.001).

CONCLUSIONS

cQTD decreases after PCI. A defective cQTD recovery, suggesting the persistence of repolarisation inhomogeneities, predicts long-term cardiac mortality.

Awake systolic blood pressure variability correlates with target-organ damage in hypertensive subjects

Growing evidence associates blood pressure (BP) variability with cardiovascular events in hypertensive patients. Here we tested the existence of a relationship between awake BP variability and target-organ damage in subjects referred for suspected hypertension. Systolic and diastolic BP variability were assessed as the standard deviation of the mean out of 24-hour, awake and asleep BP recordings in 180 untreated subjects, referred for suspected hypertension. Measurements were done at 15-minute intervals during daytime and 30-minute intervals during nighttime. Left ventricular mass index (by echo), intima-media thickness (by carotid ultrasonography), and microalbuminuria were assessed as indices of cardiac, vascular and renal damage, respectively. Intima-media thickness and left ventricular mass index progressively increased across tertiles of awake systolic BP variability (P for trend=0.001 and 0.003, respectively). Conversely, microalbuminuria was similar in the 3 tertiles (P=NS). Multivariable analysis identified age (P=0.0001), awake systolic BP (P=0.001), awake systolic BP variability (P=0.015) and diastolic BP load (P=0.01) as independent predictors of intima-media thickness; age (P=0.0001), male sex (P=0.012), awake systolic (P=0.0001) and diastolic BP (P=0.035), and awake systolic BP variability (P=0.028) as independent predictors of left ventricular mass index; awake systolic BP variability (P=0.01) and diastolic BP load (P=0.01) as independent predictors of microalbuminuria. Therefore, awake systolic BP variability by non-invasive ambulatory BP monitoring correlates with sub-clinical target-organ damage, independent of mean BP levels. Such relationship, found in subjects referred for recently suspected hypertension, likely appears early in the natural history of hypertension.