Habil Yücel

Mean platelet volume in patients with prehypertension and hypertension

Patients with hypertension have evidence of platelet activation. Mean platelet volume (MPV), an indicator of platelet activation has been shown to be elevated in patients with hypertension. Prehypertension is also associated with an increase in cardiovascular morbidity and mortality. The aim of this study was to assess the MPV in patients with prehypertension and hypertension. This study included newly diagnosed and untreated 87 prehypertensive patients, 30 hypertensive patients and 35 normotensive control subjects matched for age, gender, and body mass index. All patients and controls gave informed consent. The MPV values of patients with prehypertension and hypertension were significantly higher than those of the control group (8.4 +/- 0.8 and 8.8 +/- 0.7 versus 7.9 +/- 0.5 fl; p < 0.05 and p < 0.001 respectively). It was also higher in hypertensives than in prehypertensives (8.8 +/- 0.7 versus 8.4 +/- 0.8 fl; p < 0.05). However, we found that the presence of the hypertension (beta = 0.28, P = 0.003) was only significant predictors of higher MPV in a multivariable model that adjusted for other variables. We have shown that, MPV, an indicator of platelet activation was significantly higher in patients with prehypertension and hypertension when compared with control subjects. We have also showed that MPV was also higher in patients with hypertension than in patients with prehypertension. However, presence of the hypertension was only significant predictor of higher MPV.

Effects of normal blood pressure, prehypertension, and hypertension on autonomic nervous system function

BACKGROUND Autonomic nervous system plays an important role in blood pressure (BP) regulation, and large proportion of patients with hypertension have increased sympathetic and decreased parasympathetic activity. Heart rate recovery (HRR) is a simple non-invasive measurement for investigating autonomic nervous system influence on the cardiovascular system; however, this methodology has not been used to evaluate autonomic nervous system in subjects with prehypertension (PHT). Accordingly, the present study was designed to evaluate HRR in subjects with PHT. METHODS AND RESULTS We measured HRR of 91 subjects with PHT, 44 patients with hypertension, and 53 normotensive healthy volunteers. HRR was significantly lower in the HT and PHT groups as compared to the control group (24.4 ± 5.7, 26.0 ± 8.4, 30.0 ± 8.7; hypertension, PHT, and control groups, respectively), but it did not significantly differ between HT and PHT groups. HRR was significantly and inversely correlated with age, systolic and diastolic BP, fasting and postprandial glucose level, waist circumference, total cholesterol, LDL cholesterol and non-HDL cholesterol, whereas exercise duration and METs were positively correlated with HRR. In multivariable analysis, we found that systolic BP, postprandial glucose level and exercise duration were independent predictors of lower HRR. CONCLUSIONS HRR, a non-invasive measurement analyzing the dysfunction in autonomic nervous system, was reduced in subjects with PHT as compared to normotensives, and the subjects with PHT had HRR as lower as patients with HT did. Our findings are supportive for the hypothesis that autonomic dysregulation is present in an early stage of essential hypertension.

The effects of continuous positive airway pressure therapy on mean platelet volume in patients with obstructive sleep apnea

Previous studies have reported increased platelet activation and aggregation in patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) treatment has been shown to decrease platelet activation. We aimed to study the effects of nasal CPAP therapy has on MPV values in patients with severe OSA. Thirty-one patients (21 men; mean age 53.8 ± 9.2 years) with severe OSA (AHI > 30 events/hour) constituted the study group. An age, gender and body mass index (BMI) matched control group was composed 25 subjects (14 men; mean age 49.6 ± 8.5 years) without OSA (AHI < 5 events/hour). We measured MPV values in patients with severe OSA and control subjects and we measured MPV values after 6 months of CPAP therapy in severe OS patients. The median (IQR) MPV values were significantly higher in patients with severe OSA than in control group (8.5 [8.3–9.1] vs. 8.3 [7.5–8.8] fL; p = 0.03). The platelet counts were significantly lower in patients with severe OSA than in control group (217.8 ± 45.9 vs. 265.4 ± 64.0 × 109/L; p = 0.002). The six months of CPAP therapy caused significant reductions in median (IQR) MPV values in patients with severe OSA (8.5 [8.3–9.1] to 7.9 [7.4–8.2] fL; p < 0.001). Six months of CPAP therapy caused significant increase in platelet counts when compared with baseline values (217.8 ± 45.9 to 233.7 ± 60.6 × 109/L; p < 0.001). We have found that the MPV values of patients with severe OSA were significantly higher than those of the control subjects and 6 months CPAP therapy caused significant reductions in the MPV values in patients with severe OSA.

Metoprolol vs. carvedilol or carvedilol plus N-acetyl cysteine on post-operative atrial fibrillation: a randomized, double-blind, placebo-controlled study

AIMS Carvedilol and N-acetyl cysteine (NAC) have antioxidant and anti-inflammatory properties. Aim was to evaluate the efficacy of metoprolol, carvedilol, and carvedilol plus NAC on the prevention of post-operative atrial fibrillation (POAF). METHODS AND RESULTS Patients undergoing cardiac surgery (n = 311) were randomized to metoprolol, carvedilol, or carvedilol plus NAC. Baseline characteristics were similar. The incidence of POAF was lower in the carvedilol plus NAC group compared with the metoprolol group (P < 0.0001) or the carvedilol group (P = 0.03). There was a borderline significance for lower POAF rates in the carvedilol group compared with the metoprolol group (P = 0.06). Duration of hospitalization was lower in the carvedilol plus NAC group compared to the metoprolol group (P = 0.004). Multivariate independent predictors of POAF included left-atrial diameter, hypertension, bypass duration, pre-randomization and pre-operative heart rates, carvedilol plus NAC group vs. metoprolol group, and carvedilol plus NAC group vs. carvedilol group. CONCLUSION Carvedilol plus NAC decreased POAF incidence and duration of hospitalization compared with metoprolol and decreased POAF incidence compared with carvedilol.

Effects of prediabetes and diabetes on left ventricular and coronary microvascular functions

BACKGROUND Coronary flow reserve (CFR) provides independent prognostic information in diabetic patients with known or suspected coronary artery disease. However, there have been no substantial data to evaluate CFR in prediabetics. Accordingly, we aimed to evaluate CFR in subjects with prediabetes using second harmonic transthoracic Doppler echocardiography. METHODS AND RESULTS We measured CFR of 65 subjects with prediabetes, 45 patients with overt type 2 diabetes, and 43 sex and age matched normoglycemic healthy subjects with normal glucose tolerance. Ages, gender, existence of hypertension or hypercholesterolemia, smoking status were similar among the groups. CFR was significantly lower in diabetics (2.15 ± 0.39) than in prediabetics (2.39 ± 0.45) and controls (2.75 ± 0.35); in addition, it was significantly lower in prediabetics than controls. Only 2 (5%) of control subjects had abnormal CFR (<2) but 11 (17%) prediabetic subjects and 19 (42%) diabetic patients had abnormal CFR. We found that only age (β=-0.31, P<0.01) and presence of the diabetes (β=-0.57, P<0.01) were significant predictors of lower CFR in a multivariable model that adjusted for other variables. CFR was significantly and inversely correlated with age (r=-0.15, P=0.04), fasting glucose level (r=-0.27, P=0.001), postprandial glucose level (r=0.43, P<0.001), hemoglobin A1C level (r=-0.34, P<0.001), LDL cholesterol level (r=0.22, P=0.009), mitral A velocity (r=-0.27, P=0.001) and Tei index (r=-0.19, P=0.02), whereas mitral E/A ratio, mitral Em (r=0.18, P=0.02), mitral Em/Am ratio (r=0.23, P=0.004) were significantly and positively correlated with CFR. CONCLUSION CFR is impaired in subjects with prediabetics, but this impairment is not as severe as that in diabetics.

Increased Mean Platelet Volume in Patients With Aortic Stenosis

Background: Systemic thromboembolism is a serious complication in patients with aortic stenosis (AS). Previous studies have demonstrated that platelet activation occurs in patients with AS. The aim of this study was to assess the mean platelet volume (MPV), an indicator of platelet activation in patients with AS. Patients and Methods: The study group consisted of 43 patients with AS. An age-, gender-, and body mass index−matched control group consisted of 35 healthy volunteers. All patients and control participants underwent echocardiographic examination. We measured the serum MPV values in patients and control participants. Results: Mean platelet volume was significantly higher among patients with AS when compared with the control group (8.7 ± 1.0 vs 7.9 ± 0.9 fL, respectively; P = .001). Conclusion: We have shown that MPV was significantly elevated in patients with AS compared to control participant.

Plasma concentrations of asymmetric dimethylarginine, nitric oxide and homocysteine in patients with slow coronary flow

Abstract Objectives. Slow coronary flow (SCF) is slow progression of contrast agent in the coronary arteries in the absence of stenosis in epicardial coronary vessels. Endothelial dysfunction and diffuse atherosclerosis have been proposed for the etiology of SCF. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthesis, levels are associated with an increased risk of endothelial dysfunction and atherosclerosis. ADMA levels may be increased by homocysteine. The aim of this study was to evaluate the relationship between ADMA, nitric oxide and homocysteine in patients with SCF. Methods. The study group consisted of 50 patients with SCF. An age- and gender-matched control group was composed of 30 patients with normal coronary arteries and normal coronary flow on coronary angiography. We measured ADMA, nitric oxide and homocysteine plasma concentrations in all patients. Results. Plasma nitric oxide concentrations were significantly lower in the SCF group than in the control group (11.4 ± 6, 16.1 ± 9, p = 0.02). Plasma ADMA concentrations (0.9 ± 0.3, 0.7 ± 0.3, p = 0.01) and plasma homocysteine concentrations (12.4 ± 5, 9.8 ± 2, p = 0.03) were significantly higher in the SCF group than control group. The mean TIMI frame count (TFC) was significantly correlated with plasma ADMA (r = 0.26, p = 0.02) and homocysteine (r = 0.28, p = 0.02) concentrations, but not with nitric oxide concentrations (r = − 0.18, p = 0.13). In linear regression analysis, plasma ADMA concentrations (β = 4.6, p = 0.005) and homocysteine concentrations (β = 0.2, p = 0.03) were independently and positively associated with mean TFC. Conclusion. Our results suggest that plasma concentrations of ADMA and homocysteine are increased in SCF and also that these are independent predictors of SCF.

Evaluation of plasma oxidative status in patients with slow coronary flow.

BACKGROUND Slow coronary flow (SCF) is a coronary microvascular disorder characterised by delayed opacification of coronary vessels in a normal coronary angiogram. Coronary endothelial dysfunction plays an important pathogenetic role in patients with SCF. Oxidative stress is associated with cardiovascular diseases. AIM To assess the total antioxidant capacity (TAC) and total oxidative status (TOS) in patients with SCF. METHODS The study included 36 patients with SCF. An age- and gender-matched control group was composed of 30 patients with normal coronary arteries and normal coronary flow. We measured plasma TAC and TOS levels and oxidative stress index(OSI) value in patients and control subjects. Linear regression analysis was performed to identify factors associated with the mean TIMI frame count (TFC). RESULTS Plasma TOS level and OSI value were significantly higher in the SCF group compared to the control group (p = 0.005 and p = 0.004, respectively). However, there was no significant difference in plasma TAC levels between the groups (p = 0.104). Factors associated with mean TFC were plasma TOS levels (β = 0.425, p = 0.002) and fasting glucose levels (β = 0.099, p = 0.01) in linear regression analysis. CONCLUSIONS We found that plasma TOS and OSI were significantly higher in SCF compared to the control group and plasma TOS levels were independently associated with mean TFC.

Heart rate variability and heart rate recovery in patients with coronary artery ectasia.

BackgroundCoronary artery ectasia (CAE) is characterized by an abnormal dilatation of the coronary arteries, which is a variant of coronary artery disease (CAD). Increased sympathetic activity or decreased vagal modulation of cardiac function assessed by heart rate variability (HRV) analysis has been associated with an increased risk of coronary artery disease and mortality and angiographic progression of coronary atherosclerosis, as well as arrhythmia and sudden cardiac death. Heart rate recovery index is a strong indicator of risk in asymptomatic and symptomatic CAD. To the best of our knowledge, no study has been conducted to investigate the relationship between HRV, heart rate recovery, and CAE. The purpose of this study was to examine the changes in heart rate recovery and HRV measurements in coronary artery ectasia. MethodsThe study population consisted of 50 consecutive patients (24 women; mean age 46±5 years) with CAE, and 35 asymptomatic healthy individuals comprised the control group (19 women; mean age 44±7 years). We performed electrocardiography, echocardiography, Holter analysis, exercise stress test, routine biochemical tests and evaluated the clinical characteristics. Time-domain parameters of HRV (mean R–R intervals; standard deviations of all N–N intervals; standard deviations of the averages of N–N intervals), the root mean square of the difference in successive R–R intervals, proportion derived by dividing the number of interval differences of successive N–N intervals greater than 50 ms by the total number of N–N intervals (pNN50) were evaluated. Heart rate recovery was defined as the difference in the heart rate from peak exercise to 1 min after peak exercise. ResultsStandard deviations of all N–N intervals (123.7±30.3 vs. 178.8±52.7, P<0.001), standard deviations of the averages of N–N intervals (95.2±27.1 vs. 120.2±39.6, P = 0.001), total number of N–N intervals (11.9±8.6 vs. 17.1±6.4, P = 0.004) were significantly lower in the CAE group than in healthy controls. The root mean square of the difference in successive R–R intervals was lower in CAE patients than controls, but the differences between groups were not statistically significant (47.5±23.1 vs. 56.2±23.6, P = 0.097). The heart rate recovery values measured during the recovery phase were significantly lower in the CAE group compared with the control group (21.3±11.1 vs. 29.3±11.9, P = 0.002). The incidence of abnormal heart rate recovery [22 (44%) vs. 5 (14%), P = 0.002] was greater in patients with CAE group than in controls. ConclusionThe results of this study showed that time-domain HRV parameters and heart rate recovery were reduced in patients with CAE.

The effects of good glycaemic control on left ventricular and coronary endothelial functions in patients with poorly controlled Type 2 diabetes mellitus

Diabetics are at risk for developing overt heart failure and subclinical left ventricular (LV) dysfunction. Also, impaired coronary flow reserve (CFR) reflecting coronary microvascular dysfunction is common in diabetics. However, no substantial data regarding the effects of good glycaemic control on subclinical LV dysfunction and CFR are available.