Potential triggering of repetitive nonreentrant ventriculoatrial synchrony by loss of atrial capture.

BACKGROUND: Data on the factors that trigger repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) are limited. We hypothesize that loss of atrial capture may trigger RNRVAS. We aimed to use an atrial threshold test to observe the development of RNRVAS upon loss of atrial capture in patients with implantable cardiac electronic devices (CIED). METHODS: Patients with DDD mode CIEDs [177 patients, 67.5 ± 14.8 (70) years; 70 women] were included. Atrial threshold test was done in DDD mode at a rate at least 10 beats above the basal heart rate, with an AV delay of 300 ms (range 250-350). A multivariable logistic regression model was used to assess the independent predictors of RNRVAS. RESULTS: RNRVAS was observed in 69 of the 177 patients (39.0%) during atrial threshold test. In patients with VA conduction, incidence of RNRVAS increased to 76.7%. In univariate analysis, younger age (p = .038) and the presence of VA conduction (p < .001) were associated with an increased risk of RNRVAS, whereas complete AV block or any AV node conduction defect (p < .001) and the ventricular pacing ratio (p = .001) were inversely related to the risk of RNRVAS occurrence after loss of atrial capture. In multivariate analysis complete AV block (p = .009) and ventricular pacing ratio (p = .029) appeared as independent factors inversely related to the risk of RNRVAS development. CONCLUSION: In this study, we demonstrated that loss of atrial capture results in RNRVAS in one-third of patients with a CIED in DDD mode, and in three-fourths of those with VA conduction under certain predisposing CIED settings.

The relationship between 25-hydroxyvitamin D levels and ambulatory arterial stiffness index in newly diagnosed and never-treated hypertensive patients.

OBJECTIVES: Vitamin D insufficiency has been shown to be associated with cardiac dysfunctions, such as cardiac hypertrophy and hypertension, in animal studies. Arterial stiffness is a prognostic marker for cardiovascular disease. Previous studies have demonstrated that 25-hydroxyvitamin D [25(OH)D] levels were negatively correlated with arterial stiffness index. The aim of this study was to investigate the relationship between 25(OH)D levels and arterial stiffness, which is evaluated using an ambulatory arterial stiffness index (AASI), in patients who have untreated and newly diagnosed essential hypertension. DESIGN: A total of 123 consecutive patients with newly diagnosed and untreated essential hypertension were included. Patients were divided into two groups according to their 25(OH)D levels. Vitamin D insufficiency was defined by 25(OH)D levels less than 20 ng/ml. All patients were referred for ambulatory blood pressure monitoring. The regression slope of diastolic and systolic blood pressure was computed for each individual on the basis of ambulatory blood pressure readings. AASI was described as one minus the respective regression slope. RESULTS: The mean AASI was significantly higher in patients with 25(OH)D levels less than 20 as compared with patients with 25(OH)D levels greater than or equal to 20 (0.50±0.20 vs. 0.34±0.17, P<0.001). In Pearson's correlation analysis, AASI had a significantly strong negative correlation with vitamin D levels (r=-0.385, P<0.001). In multivariate linear regression analysis, vitamin D levels were found to be significantly and independently associated with AASI (ß=-0.317, P=0.035). CONCLUSION: Arterial stiffness measured by AASI in newly diagnosed and untreated patients with essential hypertension were significantly related to vitamin D levels.

Association between gamma-glutamyltransferase and coronary artery calcification.

BACKGROUND: The exact mechanisms behind the association between atherosclerosis and gamma-glutamyltransferase (GGT) are unclear. Coronary artery calcification (CAC) detected by computerized tomography is an important marker of atherosclerosis and its severity correlates with coronary plaque burden. The aim of this study was to investigate if serum GGT levels are associated with CAC in patients without known coronary heart disease (CHD) who had low-intermediate risk for CHD. METHODS: Two hundred and seventy two patients who had low-intermediate risk for coronary artery disease were included in the study. Serum GGT levels were measured spectrophotometrically. CACS (Agatston method) were performed using a 64-slice computerized tomography scanner. The patients were grouped according to their GGT values in four quartiles. RESULTS: Patients in higher GGT quartiles had elevated CAC score (P<0.001). Patients in higher GGT quartiles were predominantly males (P<0.001) and were more likely to be smoking (P=0.004), and have elevated uric acid (P<0.001), fasting blood glucose (P<0.001), CRP levels (P=0.003) and 10-year total cardiovascular risk (P=0.007) and low HDL levels (P<0.001). Positive correlations were found between log GGT and CAC (r=0.233, P<0.001). In the multivariate analysis GGT, age, smoking and serum uric acid levels appeared as independent factors predictive of presence of CAC. CONCLUSIONS: We demonstrated a significant correlation between serum GGT levels and CAC and CHD risk factors. Serum GGT level was an independent marker of CAC.

Serum uric acid level is an independent risk factor for presence of calcium in coronary arteries: an observational case-controlled study.

OBJECTIVE: A link between uric acid levels and cardiovascular diseases has been previously reported. Coronary artery calcium score (CACS) is a marker of atherosclerotic disease and a predictor of cardiovascular events. We sought to determine if serum uric acid level is an independent risk factor for the presence of calcium in coronary arteries. METHODS: Four hundred and forty-two patients who were evaluated in the cardiology outpatient clinic for suspected coronary heart disease with a low-moderate risk for coronary artery disease were included in this observational case-controlled study. Serum uric acid levels were measured with colorimetric methods. CACS were performed using a 64-slice CT scanner. Patients were divided to 3 groups according to their CACS value (Group 1: CACS=0, Group 2: CACS 1-100, Group 3: CACS>100). RESULTS: The demographical characteristics and laboratory findings of 3 groups were similar, except age, fasting glucose levels and serum uric acid levels. Serum uric acid levels were found to increase significantly with increasing CACS (p=0.001). Patients were grouped according to presence CAC (CACS=0 and CACS≥1) and in the multiple regression analysis, age (OR, 1.11, 95% CI, 1.07-1.16), smoking (OR, 3.83, 95% CI, 2.06-7.09), serum uric acid levels (OR, 1.26, 95% CI, 1.04-1.54) and average 10-year total risk of Framingham risk score (OR, 1.13, 95% CI, 1.04-1.09) appeared as independent factors predictive of presence of CAC (p<0.05). CONCLUSION: Serum uric acid level is an independent risk factor for presence of coronary calcium. Moreover, increasing levels of serum uric acid are associated with increasing CACS.

[Two cases of acute coronary syndrome after intake of Clavis Panax]. / Clavis Panax kullanimi sonrasi gelisen akut koroner sendrom.

Atherosclerotic cardiovascular disease is an epidemic in today's world. It is one of the most common causes of hospitalization and death. Therefore, remedies to control or heal the disease are continuously sought. In addition to scientifically researched therapies, patients frequently utilize alternative medicine. However, effective and toxic doses, metabolisms, and drug interactions of the herbs and herbal nutrition supplements are largely unknown. Herein, we present two cases with acute coronary syndrome. The first case was admitted with a diagnosis of acute inferior myocardial infaction (MI) and a stent was implanted to the occluded right coronary artery (RCA). There was a 50% stenosis in his left anterior descending artery (LAD). He was admitted with a diagnosis of non-ST elevation MI (NSTEMI) 6 months later. In the coronary angiogram, there was stent restenosis in RCA, the lesion in LAD had become thrombotic and progressed to a stenosis of 90%. He was referred to surgical revascularization. The second case was admitted for acute inferior MI and a stent was implanted to the occluded circumflex artery. Two months later, he was hospitalized for NSTEMI. Progression of coronary plaques to stenosis and stent restenosis was detected and he was referred to surgical revascularization. Both patients used the product sold as Clavis Panax, which contains panax ginseng, tribulus terrestris, and oat, after their first coronary intervention. Intake of a mixture of plant extracts may have serious consequences in humans as drug interactions and side effects are unknown.

Coronary flow reserve in patients with diabetes mellitus and prediabetes.

BACKGROUND: Abnormalities of coronary microcirculation have been reported in patients with diabetes mellitus (DM) even in the presence of normal coronary arteries. It is unknown when the microvascular effects on coronary arteries begin to appear in the DM disease course. Coronary flow reserve (CFR), determined by pharmacological stress transthoracic Doppler echocardiography, is a reliable indicator of coronary microvascular function. We sought to determine the coronary microvascular function of prediabetic patients compared to DM patients and normal population. METHODS: Seventy-four subjects with normal coronary arteries were enrolled. DM and prediabetes were diagnosed according to American Diabetes Association criteria. All subjects had Doppler recordings of the left anterior descending artery with adenosine infusion at a rate of 0.014 mg/kg per minute. RESULTS: The demographical characteristics and laboratory findings of the three groups were similar (DM group: n = 25, mean age 62 ± 7 years, 19 females; prediabetic group: n = 25, mean age 64 ± 12 years, 21 females; control group: n = 24, mean age 63 ± 7 years, 15 females) except fasting glucose levels. CFR values of the three groups were significantly different (DM group: CFR = 1.75 ± 0.50; prediabetic group: CFR = 2.24 ± 0.43; control group: CFR = 2.38 ± 0.32, P < 0.001). CFR values of DM group were lower than those of prediabetic and control groups (DM vs. prediabetic: P < 0.001, DM vs. control: P < 0.001). However, CFR levels of prediabetic group were not different from those of the control group (P = 0.481). DM was an independent factor predictive of CFR < 2 (OR, 22.69; 95% CI, 6.47-79.51; P < 0.001). CONCLUSION: Coronary microvascular function seems to be normal in the prediabetic state, but dysfunction appears after DM becomes overt.

Platelet function analysis with two different doses of aspirin.

OBJECTIVES: We aimed to compare the level of platelet inhibition using the platelet function analyzer (PFA)-100 in patients receiving low and medium doses of aspirin. STUDY DESIGN: On a prospective basis, 159 cardiology outpatients (83 men, 76 women; mean age 60.9 ± 9.9 years) taking 100 mg/day or 300 mg/day aspirin at least for the previous 15 days were included. Of these, 79 patients (50%) were on 100 mg and 80 patients (50.3%) were on 300 mg aspirin treatment. Blood samples were collected between 09:30 and 11:00 hours in the morning. Platelet reactivity was measured with the PFA-100 system. Incomplete platelet inhibition was defined as a normal collagen/epinephrine closure time (< 165 sec) despite aspirin treatment. RESULTS: Baseline clinical and laboratory characteristics of the patient groups taking 100 mg or 300 mg aspirin were similar. The overall prevalence of incomplete platelet inhibition was 22% (35 patients). The prevalence of incomplete platelet inhibition was significantly higher in patients treated with 100 mg of aspirin (n = 24/79, 30.4%) compared with those treated with 300 mg of aspirin (n = 11/80, 13.8%) (p = 0.013). In univariate analysis, female sex (p = 0.002) and aspirin dose (p = 0.013) were significantly correlated with incomplete platelet inhibition. In multivariate analysis, female sex (OR: 0.99; 95% CI 0.9913-0.9994; p = 0.025) and aspirin dose (OR: 3.38; 95% CI 1.4774-7.7469; p = 0.003) were found as independent factors predictive of incomplete platelet inhibition. CONCLUSION: Our findings suggest that treatment with higher doses of aspirin can reduce incomplete platelet inhibition especially in female patients.

Determinants of coronary artery disease in liver transplant candidates.

OBJECTIVES: The potential for perioperative and late cardiovascular complications in liver transplant candidates makes careful preoperative risk assessment imperative. We sought to identify the determinants of coronary artery disease in liver transplant candidates. MATERIALS AND METHODS: Liver transplant candidates with end-stage liver disease who were more than 40 years old and undergoing coronary angiography were retrospectively included in this study. Patients with known coronary heart disease or valvular heart disease were excluded. Symptoms, coronary artery disease risk factors, blood tests, electrocardiogram, echocardiography, treadmill stress test, myocardial perfusion scintigraphy, and coronary angiography results were recorded. A multivariable logistic regression model was used to assess the independent predictors of coronary artery disease. RESULTS: A total of 139 patients (mean age, 52 +/- 8; 110 male [79%]) were included in the analysis. Coronary angiography revealed that 13 patients (9.4%) had coronary artery disease. The frequency of diabetes mellitus, stable angina symptoms, positive smoking status, presence of 2 or more risk factors for coronary artery disease, and mean low-density lipoprotein cholesterol levels were significantly higher in patients with coronary artery disease than in patients without coronary artery disease. The electrocardiogram, echocardiography, and noninvasive stress test results were not valuable tools in liver transplant candidates for the diagnosis of coronary artery disease. In multivariate analysis, typical angina symptoms and low-density lipoproteins cholesterol levels appeared to be independent factors that were predictive of coronary artery disease. CONCLUSIONS: Typical anginal symptoms and low-density lipoprotein cholesterol levels seem to be the best predictors of coronary artery disease in liver transplant candidates.

The clinical significance of aspirin resistance in patients with chest pain.

BACKGROUND: There are conflicting data in the literature about the clinical significance of aspirin resistance. HYPOTHESIS: We aimed to prospectively evaluate the prevalence of biochemical aspirin resistance in patients on aspirin therapy who were admitted to the emergency clinic with chest pain. We also aimed to evaluate the relation between acute coronary syndromes (ACS) and aspirin resistance. METHODS: A total of 338 patients were included in the study. Platelet reactivity was measured with the PFA-100 system (Dade Behring Inc, Deerfield, IL). Aspirin resistance determined by the PFA-100 was defined as a normal collagen and/or epinephrine closure time despite aspirin treatment (<165 s). RESULTS: Patients were divided into 4 groups: stable angina pectoris (SAP), unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI), ST-elevation myocardial infarction (STEMI), and rule out ACS. Aspirin resistance was found in 81 (24%) patients in all groups. Patients with ACS had significantly more aspirin resistance than patients with rule out ACS or patients with SAP (P < .001). In the SAP group, 31 (19.6%) patients; in the UA/NSTEMI group, 19 (35.8%) patients; in the STEMI group, 14 (50%) patients; and in the rule out ACS group, 17 (17.2%) patients had aspirin resistance (P < .001). In the multivariate analysis, cardiac biomarker elevation on admission to emergency department and platelet count appeared as independent factors predictive of aspirin resistance. CONCLUSIONS: We demonstrated that incidence of aspirin resistance was significantly higher in patients who were finally diagnosed as ACS, especially in aspirin-taking patients admitted to the emergency clinic with STEMI.

Comparative effects of losartan and nifedipine therapy on exercise capacity, Doppler echocardiographic parameters and endothelin levels in patients with secondary pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension (PHT) is associated with high mortality and morbidity. Interest has increased in the use of drugs that, because of their neurohumoral inhibitory effects, inhibit the renin angiotensin system. In this study, we sought to examine whether losartan therapy is non-inferior to nifedipine in the treatment of secondary PHT. METHODS: This prospective randomized study consisted of 63 patients (mean age, 63.7+/- 9.1 years) with PHT who underwent Doppler echocardiographic examination. A baseline 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) were performed, and the endothelin-1 level of each patient was measured. Patients were assigned to two groups receiving treatment with nifedipine (n=30) and losartan (n=33). After 2 months of treatment, those measurements were repeated. The groups were compared with regard to effectiveness for the studied parameters using 2*2 factorial ANOVA design for repeated measurements. RESULTS: When posttreatment values were compared with baseline values in both groups, the following statistically significant changes were noted: the mean values of both mean and systolic pulmonary artery pressures (PAPs) were reduced (p<0.05) on Doppler echocardiography; exercise duration, work rate, and end-tidal carbon dioxide pressure (PETCO2) were higher (p<0.05 for all); and the minute ventilation (VE) and ventilatory equivalents for carbon dioxide (VE/VCO2) were lower (p<0.05 for both) according to the results of a CPET. No statistically significant change was noted in the mean levels of serum endothelin-1. With regard to the results cited above, no statistically significant difference was detected between the losartan and nifedipine groups (p>0.05). CONCLUSION: The findings of this study indicate that losartan is non-inferior to nifedipine for reducing PAP and improving exercise capacity. However, the short-term use of losartan or nifedipine had no statistically significant effect on endothelin-1 levels in patients with secondary PHT.

Adenosine-induced ventricular arrhythmias in patients with supraventricular tachycardias.

BACKGROUND: Adenosine is widely used for the diagnosis and the termination of supraventricular arrhythmias. There are many case reports and few series about the proarrhythmic potential of adenosine. We sought to evaluate the proarrhythmic potential of adenosine used to terminate the supraventricular arrhythmias. METHODS: The records of all patients that received adenosine for the termination of supraventricular tachycardia were reviewed retrospectively and those with a continuous electrocardiographic (ECG) recording during adenosine administration were included to the study. RESULTS: Our search identified 52 supraventricular episodes of 46 patients with a continuous ECG recording during adenosine administration. Following adenosine administration, premature ventricular contraction (PVC) or ventricular tachycardia (VT) developed in 22 (47.8%) patients and in 26 (50%) tachycardia episodes. No patient had a sustained VT. Nonsustained VT developed in eight (17.4%) patients. All VT episodes were polymorphic, short, and self-terminating. When the basal and demographic properties of patients with PVC or VT and those without PVT or VT were compared, there was no significant difference. CONCLUSIONS: Adenosine is a quite safe and effective drug for the termination of narrow QRS complex tachycardia but it often induces nonsustained VT or PVC that are clinically insignificant in the absence of other accompanying heart disease.

The effects of prior calcium channel blocker therapy on creatine kinase-MB levels after percutaneous coronary interventions.

BACKGROUND: Use of intracoronary calcium channel blockers (CCBs) during percutaneous coronary intervention (PCI) has been shown to have favorable effects on coronary blood flow. We aimed to investigate the effects of CCBs administrated perorally on creatine kinase-MB (CK-MB) levels in patients undergoing elective PCI. METHODS: A total of 570 patients who underwent PCI were evaluated for CK-MB elevation. Patients who were on CCB therapy when admitted to the hospital constituted the CCB group. No CCBs were given to the rest of the patients during the periprocedural period and these patients served as the control group. Blood samples for CK-MB were obtained before and at 6 h, 24 h, and 36 h after the procedure. RESULTS: 217 patients were in the CCB group (mean age 60.2 +/- 9.3 years, 162 males), and 353 were in the control group (mean age 60.0 +/- 10.1 years, 262 males). CK-MB levels increased above the normal values in 41 patients (18.9%) of the CCBs group and in 97 patients (27.5%) of the control group (p = 0.02). Median CK-MB levels were significantly higher in the control group for all studied hours (for all p < 0.05). CONCLUSIONS: Prior oral CCB therapy may have favorable effects in preventing myocyte necrosis after elective PCI.

Frequency of atrial fibrillation and factors related to its development in dialysis patients.

BACKGROUND: The frequency of atrial fibrillation is increased in patients with end-stage renal disease. In this study, we sought to determine the incidence of persistent and paroxysmal atrial fibrillation in patients with end-stage renal disease and to identify the risk factors associated with this arrhythmia. METHODS: Two hundred seventy-five patients with end-stage renal disease who were in a hemodialysis program for at least 4 months were included in the study. Patients with permanent, persistent, or paroxysmal atrial fibrillation were identified and recorded. All patients were evaluated for cardiac risk factors and arrhythmias. RESULTS: Thirty (10.9%) of the 275 patients were found to have atrial fibrillation. Ten (33.3%) of these patients had permanent or persistent atrial fibrillation, and 20 (66.6%) of these patients had paroxysmal atrial fibrillation. Patients with atrial fibrillation were older. Incidences of hypertension, coronary artery disease, left ventricular systolic dysfunction, right atrial diameters, and mitral and/or aortic calcification were significantly higher in patients with atrial fibrillation. Serum albumin and high-density lipoprotein levels were significantly lower in patients with atrial fibrillation. CONCLUSIONS: Our data indicate that atrial fibrillation is a frequent arrhythmia in patients with end-stage renal disease, and the most frequently encountered form is paroxysmal atrial fibrillation. In this patient group, presence of coronary artery disease, age, and right atrial diameter are independent factors for determination of the risk of development of atrial fibrillation.

The effects of prior beta-blocker therapy on serum C-reactive protein levels after percutaneous coronary intervention.

BACKGROUND: There are no studies in the literature related to the effect of beta blockers (BB) on changes in C-reactive protein (CRP) levels after percutaneous coronary intervention (PCI). HYPOTHESIS: We designed a prospective randomized study to investigate the impact of BB therapy on CRP in patients who underwent elective PCI. METHODS: In all, 300 patients with coronary artery disease were included. Patients were randomized to either a metoprolol or to a control group before PCI. Blood samples for CRP levels were obtained before BB treatment, and at the 6th, 24th, and 36th h after PCI. RESULTS: Of 300 patients, 150 received metoprolol 100 mg/day (mean age, 59.0 +/- 10.2 years; 106 men, 44 women), and 150 received no BB (mean age, 59.8 +/- 9.8 years; 114 men, 36 women) and served as the control group. Baseline clinical characteristics of both groups were similar. Basal CRP levels between the two groups were similar. Of the patients included in the study, 40.8% in the BB group and 39.6% in the control group had elevated basal CRP levels. The CRP levels increased above baseline values in 85% of patients in the BB group and in 89.3% of patients in the control group (p > 0.05) during follow-up. The CRP levels in patients in the BB group at the 6th, 24th, and 36th h were lower than those in the control group; however, this difference did not reach statistical significance. CONCLUSIONS: Prior BB therapy seems to have no effect on CRP levels after PCI.