Relationships between reduced heart rate variability and pre-clinical cardiovascular disease in patients with type 2 diabetes.

AIMS: Reduced heart rate variability (HRV), an early sign of diabetic cardiovascular autonomic neuropathy (CAN), is associated with worse cardiovascular outcomes. The objective was to evaluate relationships between HRV parameters and three pre-clinical cardiovascular disease markers (left ventricular hypertrophy [LVH], aortic stiffness and carotid atherosclerosis) in type 2 diabetes. METHODS: In a cross-sectional study, 313 patients with type 2 diabetes performed 24-h Holter monitoring, carotid ultrasonography (intima-media thickness and plaques measurements), aortic pulse wave velocity measurement and echocardiography (left ventricular mass index [LVMI] measurement). Time-domain HRV parameters were the standard deviation of all normal RR intervals (SDNN), the standard deviation of the averaged normal RR intervals for all 5min segments (SDANN), the root mean square of differences between adjacent R-R intervals (rMSSD), and the percentage of adjacent R-R intervals that varied by >50ms (pNN50). Multivariate linear and logistic regressions assessed associations between HRV parameters and the three markers of pre-clinical cardiovascular disease. RESULTS: Patients with reduced HRV had longer diabetes duration, greater prevalences of microvascular complications, lower physical fitness, and higher heart rate, glycated hemoglobin, albuminuria and LVMI than patients with normal HRV. On multivariate regressions, after adjustments for several confounders, reduced SDNN and SDANN were independently associated with LVH and aortic stiffness. No HRV parameter was associated with carotid atherosclerosis. CONCLUSIONS: Two reduced HRV parameters, SDNN and SDANN, which reflect cardiovascular autonomic imbalance, were associated with LVH and aortic stiffness, markers of pre-clinical cardiovascular disease. These findings may offer insights into physiopathological mechanisms linking CAN to worse cardiovascular prognosis.

High fitness is associated with a better cardiovascular risk profile in patients with type 2 diabetes mellitus.

Novel cardiovascular risk markers, such as ambulatory blood pressure (BP) and aortic stiffness, have been proposed. The aim of this study was to investigate the relationship between physical fitness and some of these risk markers in 575 type 2 diabetic patients. In a cross-sectional design, clinical, laboratory, echocardiographic, aortic pulse wave velocity and 24-h ambulatory BP monitoring data were obtained. Fitness was self-reported using a standard questionnaire of daily activities, and then assessed as belonging to one of the three categories: low (<4 metabolic equivalents (METs)), moderate (≥ 4 to <7 METs) and high fitness (≤ 7 METs). In a random sub-sample of 265 patients, self-reported fitness was confirmed by a standard treadmill test. Statistical analysis was carried out, using tests including bivariate tests among the three categories and multivariate logistic regression. Agreement between self-reported and measured fitness was substantial (weighted κ: 0.63). High fitness patients were younger, frequently male, had a decreased prevalence of degenerative complications, lower office and ambulatory BP levels, particularly during the night and had an increased prevalence of the normal nocturnal dipping pattern. High fitness patients also had lower hemoglobin A1c and C-reactive protein levels, a decreased prevalence of left ventricular hypertrophy and increased aortic stiffness. On multiple logistic regression, after adjustments for several confounders, high fitness was independently associated with a higher likelihood of having low C-reactive protein (odds ratio (OR): 2.3, 95% confidence interval (CI): 1.3-3.9), controlled nighttime BP (OR: 2.3, 95% CI: 1.4-3.8), normal dipping pattern (OR: 2.1, 95% CI: 1.2-3.5) and low aortic stiffness (OR: 2.5, 95% CI: 1.3-4.8). Patients with moderate fitness had intermediate OR. In conclusion, a moderate to high level of physical fitness was independently associated with several favorable intermediate cardiovascular risk markers, which may contribute to decreasing the burden of morbi-mortality in patients with type 2 diabetes.

Prognostic significance of baseline and serial changes in electrocardiographic strain pattern in resistant hypertension.

OBJECTIVES: The prognostic importance of serial changes in electrocardiographic strain pattern of lateral ST-depression and T-wave inversion is unclear. The objective was to evaluate the significance of baseline and serial changes in strain pattern as predictors of cardiovascular morbidity and mortality in patients with resistant hypertension. METHODS: At baseline and during follow-up, 532 resistant hypertensive patients had the presence of strain pattern examined on 12-lead ECGs. Other clinical laboratory, echocardiographic and ambulatory blood pressure data were obtained. Primary endpoints were a composite of total cardiovascular events and mortality. Strokes and coronary heart disease events were secondary endpoints. Multiple Cox regression assessed the associations between strain pattern and subsequent endpoints. RESULTS: At baseline, 115 patients (21.6%) presented the strain pattern and during follow-up, 17 patients regressed and 22 developed new strain pattern. After a median follow-up of 4.8 years, 69 patients died, 46 from cardiovascular causes; and 107 cardiovascular events occurred, 44 strokes and 42 coronary heart disease events. After adjustment for several cardiovascular risk factors, including time-varying ambulatory blood pressures and electrocardiographic voltage criteria of left ventricular hypertrophy, the persistence or development of strain during follow-up was a predictor of the composite endpoint (hazard ratio 1.97, 95% confidence interval 1.19-3.25), all-cause mortality (hazard ratio 1.99, 95% confidence interval 1.10-3.61) and of stroke (hazard ratio 3.09, 95% confidence interval 1.40-6.81). The combination of strain pattern and left ventricular hypertrophy voltage criteria improved stratification of cardiovascular risk. CONCLUSION: Serial changes in electrocardiographic strain pattern during follow-up predict cardiovascular morbidity and mortality in resistant hypertensive patients. Regression or prevention of the strain pattern during antihypertensive treatment may be a therapeutic goal to improve prognosis.