Enalapril reduces QTc dispersion in mild congestive heart failure secondary to coronary artery disease

Predictive factors of poor blood collecting flow during leukocyte apheresis for cellular therapy

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1-pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre-evaluated based on laboratory and chest X-ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2-127 min) post-initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre-evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Pharmacological interventions for heart failure in people with chronic kidney disease

BACKGROUND

Approximately half of people with heart failure have chronic kidney disease (CKD). Pharmacological interventions for heart failure in people with CKD have the potential to reduce death (any cause) or hospitalisations for decompensated heart failure. However, these interventions are of uncertain benefit and may increase the risk of harm, such as hypotension and electrolyte abnormalities, in those with CKD.

OBJECTIVES

This review aims to look at the benefits and harms of pharmacological interventions for HF (i.e., antihypertensive agents, inotropes, and agents that may improve the heart performance indirectly) in people with HF and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies through 12 September 2019 in consultation with an Information Specialist and using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials of any pharmacological intervention for acute or chronic heart failure, among people of any age with chronic kidney disease of at least three months duration.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the records to identify eligible studies and extracted data on the following dichotomous outcomes: death, hospitalisations, worsening heart failure, worsening kidney function, hyperkalaemia, and hypotension. We used random effects meta-analysis to estimate treatment effects, which we expressed as a risk ratio (RR) with 95% confidence intervals (CI). We assessed the risk of bias using the Cochrane tool. We applied the GRADE methodology to rate the certainty of evidence.

MAIN RESULTS

One hundred and twelve studies met our selection criteria: 15 were studies of adults with CKD; 16 studies were conducted in the general population but provided subgroup data for people with CKD; and 81 studies included individuals with CKD, however, data for this subgroup were not provided. The risk of bias in all 112 studies was frequently high or unclear. Of the 31 studies (23,762 participants) with data on CKD patients, follow-up ranged from three months to five years, and study size ranged from 16 to 2916 participants. In total, 26 studies (19,612 participants) reported disaggregated and extractable data on at least one outcome of interest for our review and were included in our meta-analyses. In acute heart failure, the effects of adenosine A1-receptor antagonists, dopamine, nesiritide, or serelaxin on death, hospitalisations, worsening heart failure or kidney function, hyperkalaemia, hypotension or quality of life were uncertain due to sparse data or were not reported. In chronic heart failure, the effects of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) (4 studies, 5003 participants: RR 0.85, 95% CI 0.70 to 1.02; I2 = 78%; low certainty evidence), aldosterone antagonists (2 studies, 34 participants: RR 0.61 95% CI 0.06 to 6.59; very low certainty evidence), and vasopressin receptor antagonists (RR 1.26, 95% CI 0.55 to 2.89; 2 studies, 1840 participants; low certainty evidence) on death (any cause) were uncertain. Treatment with beta-blockers may reduce the risk of death (any cause) (4 studies, 3136 participants: RR 0.69, 95% CI 0.60 to 0.79; I2 = 0%; moderate certainty evidence). Treatment with ACEi or ARB (2 studies, 1368 participants: RR 0.90, 95% CI 0.43 to 1.90; I2 = 97%; very low certainty evidence) had uncertain effects on hospitalisation for heart failure, as treatment estimates were consistent with either benefit or harm. Treatment with beta-blockers may decrease hospitalisation for heart failure (3 studies, 2287 participants: RR 0.67, 95% CI 0.43 to 1.05; I2 = 87%; low certainty evidence). Aldosterone antagonists may increase the risk of hyperkalaemia compared to placebo or no treatment (3 studies, 826 participants: RR 2.91, 95% CI 2.03 to 4.17; I2 = 0%; low certainty evidence). Renin inhibitors had uncertain risks of hyperkalaemia (2 studies, 142 participants: RR 0.86, 95% CI 0.49 to 1.49; I2 = 0%; very low certainty). We were unable to estimate whether treatment with sinus node inhibitors affects the risk of hyperkalaemia, as there were few studies and meta-analysis was not possible. Hyperkalaemia was not reported for the CKD subgroup in studies investigating other therapies. The effects of ACEi or ARB, or aldosterone antagonists on worsening heart failure or kidney function, hypotension, or quality of life were uncertain due to sparse data or were not reported. Effects of anti-arrhythmic agents, digoxin, phosphodiesterase inhibitors, renin inhibitors, sinus node inhibitors, vasodilators, and vasopressin receptor antagonists were very uncertain due to the paucity of studies.

AUTHORS' CONCLUSIONS

The effects of pharmacological interventions for heart failure in people with CKD are uncertain and there is insufficient evidence to inform clinical practice. Study data for treatment outcomes in patients with heart failure and CKD are sparse despite the potential impact of kidney impairment on the benefits and harms of treatment. Future research aimed at analysing existing data in general population HF studies to explore the effect in subgroups of patients with CKD, considering stage of disease, may yield valuable insights for the management of people with HF and CKD.

Pharmacokinetics and pharmacodynamics of enalapril and its active metabolite, enalaprilat, at four different doses in healthy horses

Pharmacokinetic and pharmacodynamic of IV enalapril at 0.50 mg/kg, PO placebo and PO enalapril at three different doses (0.50, 1.00 and 2.00 mg/kg) were analyzed in 7 healthy horses. Serum concentrations of enalapril and enalaprilat were determined for pharmacokinetic analysis. Angiotensin-converting enzyme (ACE) activity, serum ureic nitrogen (SUN), creatinine and electrolytes were measured, and blood pressure was monitored for pharmacodynamic analysis. The elimination half-lives of enalapril and enalaprilat were 0.67 and 2.76 h respectively after IV enalapril. Enalapril concentrations after PO administrations were below the limit of quantification (10 ng/ml) in all horses and enalaprilat concentrations were below the limit of quantification in 4 of the 7 horses. Maximum mean ACE inhibitions from baseline were 88.38, 3.24, 21.69, 26.11 and 30.19% for IV enalapril at 0.50 mg/kg, placebo and PO enalapril at 0.50, 1.00 and 2.00 mg/kg, respectively. Blood pressures, SUN, creatinine and electrolytes remained unchanged during the experiments.

Nebivolol therapy improves QTc and QTcd parameters in heart failure patients

Aim

It has previously been shown that β-blocker therapy reduces QT dynamics in heart failure patients. The aim of this study was to demonstrate this improvement with the third-generation β-blocker, nebivolol.

Methods

A total of 72 heart failure patients with systolic dysfunction were included in the study. Corrected QT (QTc) and QT dispersion (QTcd) were measured manually by two independent observers at baseline and after nebivolol use (5 mg/day) in the first and third months of follow up.

Results

Both QTc and QTcd were found to be significantly reduced in the first (455.3 ± 26.7 vs 441.2 ± 25.7 ms, p < 0.001 for QTc, and 65.6 ± 5.3 vs 58.2 ± 5.6 ms, p = 0.001 for QTcd) and third months (455.3 ± 26.7 vs 436.0 ± 28.7 ms, p < 0.001 for QTc, and 65.6 ± 5.3 vs 56.0 ± 6.2 ms, p < 0.001 for QTcd) compared with baseline values.

Conclusion

Nebivolol was associated with improved QT dynamics in heart failure patients with systolic dysfunction.

Increased pretransplant QT dispersion as a risk factor for the development of cardiac complications during and after preparative conditioning for pediatric allogeneic hematopoietic stem cell transplantation

Although cardiac complications are some of the most serious complications of HSCT for leukemia, it is difficult to predict them. QTD has been reported as a predictor of heart failure and fatal arrhythmia in adults. The purpose of this study is to examine whether QTD predicts cardiac complications in pediatric HSCT. Eighteen patients (mean age, 6.9 yr; 11 ALL and seven AML) underwent high-dose cyclophosphamide treatment and total body irradiation as preparative conditioning for HSCT. QTD, QTcD, echocardiographic functional parameters, and cumulative anthracycline dose were evaluated. We compared these values between patients with and without cardiac complications. Among 18 patients, seven patients experienced cardiac complications (heart failure in four, arrhythmia in three). There were significant differences in QTD (43.7 ms in patients with cardiac complications vs. 30.2 ms in patients without the complications, p = 0.019) and QTcD (55.3 vs. 36.9 ms, p = 0.003) between the two groups. On the other hand, the cumulative dose of anthracycline and echocardiographic parameters were not significantly different between the two groups. Increases in QTD and QTcD during the pretreatment period may be risk factors for the development of cardiac complications during and after conditioning for pediatric HSCT.

Efficacy and safety of atrasentan in patients with cardiovascular risk and early atherosclerosis

Endothelin plays an important role in the pathogenesis of atherosclerosis. The aim of the study was to evaluate the safety and hemodynamic and metabolic responses to 6 months treatment with atrasentan, the selective endothelin-A receptor antagonist. Seventy-two patients with multiple cardiovascular risk factors and nonobstructive coronary artery disease on coronary angiogram were randomly assigned in a double-blind manner to atrasentan or placebo. Mean aortic blood pressure decreased from 92+/-10 to 80+/-10 mm Hg (P<0.001) in the atrasentan group and did not change in the placebo group (93+/-10 and 92+/-11 mm Hg; P=0.84). The difference between the groups was significant (P<0.001). No effect on heart rate was observed. In a subgroup of patients not treated with angiotensin-converting enzyme inhibitor, creatinine level decreased in the atrasentan versus the placebo group (P=0.011). Fasting glucose (P=0.026), glycosylated hemoglobin level (P=0.041), triglyceride l (P=0.013), lipoprotein-A (P=0.046), and uric acid levels (P=0.048) decreased significantly in the atrasentan group compared with the placebo group. No progression of angiographic coronary disease was observed. The most common adverse effects with atrasentan were nasal stuffiness, headache, and edema. In conclusion, 6 months of treatment with atrasentan results in a reduction of blood pressure and improvement in glucose and lipid metabolism. These findings suggest the beneficial role of atrasentan in the treatment of hypertension and metabolic syndrome.

Possible cardioprotective effect of angiotensin-converting enzyme inhibitors during treatment of American tegumentary leishmaniasis with meglumine antimoniate

We conducted an observational retrospective study to identify factors associated with prolongation of corrected QT (QTc) interval during treatment of American tegumentary leishmaniasis with meglumine antimoniate. A group of 108 patients with normal ECG before treatment were included. Thirty-one patients (29%) developed increase of QTc interval beyond 0.44s in the second ECG performed after an average of (mean+/-S.D.) 12.6+/-4.9 days. After univariate and multivariate analysis, the age was associated with prolonged QTc interval, and the use of angiotensin-converting enzyme (ACE) inhibitors demonstrated a protective factor. These results identify elderly as a risk factor to develop prolonged QTc due to antimonial therapy (odds ratio: 1.1; 95% confidence interval: 1.01-1.12), and suggest that use of ACE inhibitors is a possible cardioprotective agent (odds ratio: 0.3; 95% confidence interval: 0.003-0.34). Further studies using prospective methodology are necessary to define the role of ACE inhibitors as prophylactic agent in high-risk patients.

Calcitriol Regresses Cardiac Hypertrophy and QT Dispersion in Secondary Hyperparathyroidism on Hemodialysis

BACKGROUND

Sudden cardiac death is common in patients on hemodialysis (HD), and its rate is as high as 25% of all cardiac deaths associated with left ventricular hypertrophy (LVH) and secondary hyperparathyroidism. A prolonged QT interval on standard electrocardiography is related to an increase in sudden death in various patient groups. It is also well known that LVH has been noted in uremic patients with high parathyroid hormone levels.

METHODS

To evaluate the response of intravenous calcitriol treatment on the QT interval and LVH in HD patients with secondary hyperparathyroidism (intact parathyroid hormone, iPTH, > 450 ng/ml), echocardiographic, electrocardiographic (ECG), and biochemical assessments were performed over a 15-week period in 25 HD patients before and after intravenous calcitriol treatment. We also evaluated 25 age-, sex-, HD duration-, and BMI-matched HD control patients with secondary hyperparathyroidism.

RESULTS

In patients receiving intravenous calcitriol, a significant reduction in iPTH levels (p < 0.05) and alkaline phosphatase levels (p < 0.01) was found without changes in values of serum calcium and ionized Ca2+, phosphorus, Na+, K+, Mg2+, hematocrit, blood pressure, or other hemodynamic changes. Echocardiograms showed significant decreases in the thickness of the interventricular septum (p < 0.05), left posterior wall thickness (p < 0.05), and left ventricle mass index (LVMi, p < 0.01). In addition, sequential ECG measurement in patients with calcitriol treatment showed significant reductions in QTcmax (QTmax interval corrected for heart rates, p < 0.01) and QTc dispersion (QT dispersion corrected for heart rates, p < 0.01). However, in the control patients, biochemical, hemodynamic, and ECG changes, as well as myocardial structural and functional changes were not seen. Multiple regression analysis in all patients indicated that iPTH and LVMi levels were independent predictors of QTcmax while the LVMi level was the only independent predictor of QTc dispersion (p < 0.05).

CONCLUSIONS

Our study showed a significant correlation between LVMi and QT dispersion in HD patients with secondary hyperparathyroidism. Intravenous calcitriol treatment, to be used for the control of secondary hyperparathyroidism, was found to cause regression of myocardial hypertrophy and a reduction in the QTc interval and dispersion, without biochemical and hemodynamic changes. These findings suggest that an active vitamin D metabolite has a cardioprotective action in HD patients.

Acute reduction of ventricular volume decreases QT interval dispersion in elderly subjects with and without heart failure

To evaluate the effects of acute reduction in ventricular volume (VV) on QT interval dispersion (QTd), 14 men with heart failure (HF; 74.5 ± 2 yr of age) and 11 healthy male control subjects (68 ± 2 yr of age) were studied. For 15 min, lower body negative pressure (LBNP) was applied at −15 and −40 mmHg to reduce venous return. At baseline and during LBNP application, QTd was measured with an 87-lead, body-surface-mapping device; chamber volumes were assessed by radioisotope ventriculography; blood pressure (BP) and heart rate (HR) were continuously monitored; and blood samples were obtained for assessment of norepinephrine (Nor) levels. At −15 mmHg, LNBP application induced a significant decrease in VV but did not change BP and HR in both groups. In addition, Nor levels increased significantly ( P ≤ 0.05) in the control group (from 286.7 ± 31.5 to 388.8 ± 41.2 pg/ml) and in HF patients (from 405.8 ± 56 to 477.6 ± 47 pg/ml), and QTd was significantly ( P ≤ 0.05) decreased in the control group (57.2 ± 3.8 vs. 49.1 ± 3.4 ms) and in HF patients (67.8 ± 6 vs. 63.7 ± 5.9 ms). No additional decreases in VV or QTd were produced by −40 mmHg LNBP, but Nor levels did increase in both groups and reach 475.5 ± 34 and 586.5 ± 60 pg/ml ( P < 0.05) in the control and HF groups, respectively; BP did not change, but HR also increased in both groups. In conclusion, an acute LBNP-induced reduction in VV caused a decrease in the QTd of elderly men regardless of the existence of HF. Because increased sympathetic activity with more intense LBNP was not accompanied by additional changes in QTd, altered QTd may be better related to changes in VV than to autonomic nervous system activity.

Clinical effects of endothelin receptor antagonism with bosentan in patients with severe chronic heart failure: results of a pilot study

BACKGROUND

Endothelin receptor antagonism produces favorable short-term hemodynamic effects in heart failure, but the clinical effects of longer term therapy have not been evaluated.

METHODS AND RESULTS

Three hundred and seventy patients with symptoms of heart failure at rest or on minimal exertion and a left ventricular ejection fraction <35% were randomly assigned (double-blind) to placebo (n = 126) or the endothelin receptor antagonist bosentan, titrated slowly (n = 121) or rapidly (n = 123) to a target dose of 500 mg twice daily. Treatment with the study drug was to be maintained for 26 weeks, whereas background medications for heart failure were kept constant. Safety concerns led to early termination of the trial when only 174 patients had had an opportunity to complete 26 weeks of therapy. Bosentan exerted no apparent benefit when all randomized patients were analyzed (P = .709). However, in the first 174 patients who were recruited at least 26 weeks before study termination and who could therefore be followed for the planned duration of the trial, patients in the bosentan groups were more likely to be improved (26% versus 19%) and were less likely to be worse (28% versus 43%), P = .045. When compared with placebo-treated patients, bosentan-treated patients had a increased risk of heart failure during the first month of treatment but a decreased risk of heart failure during the fourth, fifth, and sixth months of therapy. The major noncardiac adverse effects of bosentan included an increase in hepatic transaminases (in 15.6% of patients) and a decrease in hemoglobin (of about 1 g/L).

CONCLUSION

Although bosentan exerted no favorable effects in the overall study, our findings suggest that the clinical responses to endothelin antagonism with bosentan in patients with severe chronic heart failure may be dependent on the duration of treatment.

Effect of nebivolol on QT dispersion in hypertensive patients with left ventricular hypertrophy

Hypertensive patients with left ventricular hypertrophy (LVH) have increased QT dispersion, which is considered an early indicator of end-organ damage and a non-invasive marker of risk for clinically important ventricular arrhythmias and cardiac mortality. The purpose of this study was to examine the effect of nebivolol antihypertensive therapy on QT dispersion in hypertensive subjects. Twenty-five subjects (15 men and 10 women, mean age 53.6 +/- 4.5 years) with essential arterial hypertension and mild-to-moderate LVH (blood pressure: 147.2 +/- 6.2/90.6 +/- 3.8 mmHg; left ventricular mass indexed: 149.1 +/- 10.7 g/m(2)) were compared with 25 age-matched healthy control subjects. All the participants underwent a complete clinical examination, including electrocardiogram for QT interval measurements. The QT dispersion was defined as the difference between the longest and the shortest QT interval occurring in the 12-lead electrocardiogram. The QT dispersion was corrected (QTc) with Bazett's formula. Hypertensive subjects were treated with 5 mg daily of nebivolol. The ECG and echocardiogram were repeated after four weeks of treatment. At baseline, hypertensive patients showed QT dispersion (56.9 +/- 6.4 vs. 31.7 +/- 8.4 ms, P < 0.001) and QTc dispersion (58.3 +/- 6.2 vs. 33.2 +/- 7.8 ms, P < 0.001) significantly higher than control subjects. Four-week nebivolol treatment reduced blood pressure from 147.2 +/- 6.2/90.6 +/- 3.6 mmHg to 136.3 +/- 3.1/83.3 +/- 2.5 mmHg (P < 0.0001), and resting heart rate from 75.3 +/- 4.7 to 64.2 +/- 3.0 bpm (P < 0.001), without significant change in left ventricular mass (LVMi: 149.1 +/- 10.7 vs. 151.4 +/- 9.8 g/m(2), ns). Nebivolol-based treatment improved QT dispersion (56.9 +/- 6.4 vs. 40.5 +/- 5.8 ms, P < 0.001) and QTc dispersion (58.3 +/- 6.2 vs. 42.2 +/- 5.6 ms, P < 0.001), which remained higher than in control subjects (P < 0.001 in both cases). The reduction of QT dispersion did not correlate with arterial BP reduction. In conclusion, nebivolol reduced increased QT dispersion in hypertensive subjects after four weeks. This effect, occurred without any change in LVM, did not seem to be related to the blood pressure lowering and could contribute to reduce arrhythmias as well as sudden cardiac death in at-risk hypertensive patients.

Predictive value of QT dispersion for acute heart failure after autologous and allogeneic hematopoietic stem cell transplantation

The aim of our study was to evaluate whether corrected QT dispersion (QTc dispersion), an electrocardiographic marker, is a good predictor of the development of acute heart failure after high-dose chemotherapy followed by autologous or allogeneic hematopoietic stem cell transplantation. We enrolled 50 consecutive patients, from age 15 to 63 years, with hematopoietic diseases scheduled to undergo autologous or allogeneic hematopoietic stem cell transplantation, and compared QTc dispersion with other markers before transplantation conditioning. In univariate logistic analysis, QTc dispersion was a significant factor for acute heart failure after hematopoietic stem cell transplantation (odds ratio, 3.7 per 10 msec; confidence interval, 1.6-8.5; P = 0.002). There were no significant differences as age, sex, systolic or diastolic echocardiographic function markers, cumulative anthracycline dose, or QTc before transplantation between patients with and without acute heart failure. After multiple adjustments for left ventricular ejection fraction, cumulative anthracycline dose, cyclophosphamide conditioning dose, QTc dispersion was a significant and independent factor for acute heart failure after hematopoietic stem cell transplantation (odds ratio, 48.0 per 10 msec; confidence interval, 1.4-1666.3; P = 0.03). This study demonstrated that QTc dispersion could be used as a powerful noninvasive predictor of the development of acute heart failure after hematopoietic stem cell transplantation.

Adverse effects of ACE inhibitors in patients with chronic heart failure and/or ventricular dysfunction : meta-analysis of randomised clinical trials

BACKGROUND

The evidence-based benefit/risk evaluation of therapeutic interventions in randomised clinical trials should include both the assessment of the benefits and of the adverse outcomes. There is ample evidence that ACE inhibitors improve the symptoms and prognosis of chronic heart failure (CHF) and ventricular dysfunction. However, there is little systematic information on the tolerability and adverse effects associated with their use in these conditions.

OBJECTIVE

To estimate the adverse events related to ACE inhibitor use in the treatment of CHF and ventricular dysfunction.

DESIGN AND METHODS

Description of adverse events in reports of randomised clinical trials of ACE inhibitors in CHF or ventricular dysfunction was examined, and a meta-analysis was performed. Trials were included if they were placebo- or standard treatment-controlled, and if the treatment duration was at least 8 weeks. Relative risks and their 95% CIs were estimated with a random effects model.

RESULTS

Only 22 (43%) of 51 original reports contained information on the number of withdrawals and their causes. Missing information from the remaining 29 trials was obtained from the authors. The weighted mean duration of treatment was 100.2 weeks. After excluding administrative reasons, heart failure, myocardial infarction and hypertension, the withdrawal rates attributed to adverse events were 13.8% and 9.4% for the ACE inhibitor and control groups, respectively (RR = 1.54 [95% CI 1.30-1.83]; weighted difference = 3.1 per 100 treated patients [95% CI 1.8-4.4]). Cough, hypotension, renal dysfunction, dizziness, hyperkalaemia, and impotence were all significantly more prevalent among patients treated with ACE inhibitors than among those in the control groups.

CONCLUSIONS

Among patients with CHF or ventricular dysfunction enrolled in randomised clinical trials, treatment with an ACE inhibitor for an average of 2 years leads to an additional 3% of treatment withdrawals. In a significant proportion of the reports on these randomised clinical trials, information on adverse events leading to treatment withdrawal was inadequate. Proper evidence-based evaluation of the benefit/risk of therapeutic interventions needs a more systematic approach to reporting of adverse events experiences recorded in clinical trials.

Impaired left ventricular function is associated with increased recovery time dispersion in patients with previous myocardial infarction

Left ventricular (LV) dysfunction after myocardial infarction is associated with higher risk of serious ventricular arrhythmias and sudden death. We suspected that heterogeneity in ventricular repolarization contributes to these arrhythmias. To quantify this heterogeneity, we measured the recovery time (the interval between QRS onset and the time of maximum dV/dt in the ST-T segment) using an 87-lead body surface mapping electrocardiogram and estimated recovery time dispersion (the difference between maximum recovery time and minimum recovery time) in each lead. Differences between 110 patients with previous myocardial infarction and 31 healthy controls were compared. Recovery time dispersion [medians (25th, 75th percentiles)] was greatest in patients with a dilated LV [169 ms (154, 201) vs. 155 ms (137, 172), P <.005], impaired ejection fraction [173 ms (155, 202) vs. 152 ms (138, 165), P <.0005] and LV dyskinesis [175 ms (159, 201) vs. 155 ms (137, 161), P <.0005]. This study suggests that LV dysfunction associated with myocardial infarction leads to heterogeneous ventricular repolarization and may provide the electrical substrate for ventricular arrhythmias.

Simvastatin normalizes qtc dispersion and reduces ventricular electrical instability in isolated hypercholesterolemia

This study aimed at evaluating a possible relationship between cholesterol levels and ventricular electrical instability in human beings. Forty subjects (26 males and 14 females, mean age+/-SD 50.3+/-3.7 yr) with isolated hypercholesterolemia (> or =240 mg/dl) were selected from a population of 250 patients who attended the outpatient department of our institution for symptomatic extrasystolic activity (ventricular premature complexes >3,000/24 h). Subjects were randomly assigned to receive either simvastatin 40 mg/d or placebo for 3 consecutive months. After treatment, subjects in the simvastatin group presented a significant decrease of total cholesterol and LDL-cholesterol (p<0.001) and an increase of HDL-cholesterol levels (p<0.01), associated with a reduction of both QTc dispersion (p<0.001) and ventricular premature complexes (p<0.001). None of these changes were observed in the placebo group. At baseline, there was a relationship between cholesterol levels, ventricular premature complexes (VPC) (r=0.33, p<0.05) and QTc dispersion (r=0.41, p<0.01). After treatment, reductions in serum cholesterol levels correlated with decreases of both VPCs (r=0.37, p<0.01) and QTc dispersion (r=0.49, p<0.01). In subjects with isolated hypercholesterolemia simvastatin may reduce the cardiovascular risk associated with ventricular electrical instability.

Changes in the corrected QT interval and corrected QT dispersion during haemodialysis

The link between increased QT dispersion and cardiac death in subjects with diabetes and arterial disease is well recognised. Corrected QT dispersion was studied in subjects with end stage renal failure on haemodialysis. Thirty one stable, chronic subjects on haemodialysis had 12-lead electrocardiograms (ECGs) taken before and after a single haemodialysis session. The QT interval was measured manually in each and the corrected QT and corrected QT dispersion calculated. Serum concentrations of potassium, calcium, and magnesium were measured at the same time as ECG acquisition. Corrected QT dispersion increased from a mean (SEM) 90.6 (5.8) to 117.7 (10.2) ms (p=0.002). Serum potassium and magnesium decreased from 5.0 (0.14) to 3.5 (0.09) mmol/l and 0.95 (0.04) to 0.89 (0.09) mmol/l respectively, while serum calcium increased from 2.56 (0.04) to 2.77 (0.04) mmol/l. Intradialytic weight fell by a mean of 2.1 kg. There was no significant correlation between the change in QTc dispersion and the changes in measured serum anions or the subjects' weight during dialysis. Corrected QT dispersion was higher in subjects on haemodialysis than previously suggested normal values, and was significantly increased by haemodialysis. This reflects increased inhomogeneous ventricular repolarisation, which may lead to an increased risk of arrhythmias and sudden death. Studies looking at QT dispersion in subjects on dialysis should standardise the timing of ECG recordings taken with respect to dialysis.

The effects of chronic carvedilol therapy on QT dispersion in patients with congestive heart failure

BACKGROUND

Carvedilol therapy reduces mortality from sudden cardiac death and progressive pump failure in congestive heart failure (CHF). However, the effect(s) of carvedilol on ventricular repolarization characteristics is unclear.

AIM

The aim of the study was to investigate the effects of chronic carvedilol therapy on ventricular repolarization characteristics as assessed by QT dispersion (QTd) in patients with CHF.

METHOD

Nineteen patients (age 53+/-12 years; 16 male, three female) with CHF (eight ischemic, 11 non-ischemic dilated cardiomyopathy) were prospectively included in the study. Carvedilol was administered in addition to standard therapy for CHF at a dose of 3.125 mg bid and uptitrated biweekly to the maximum tolerated dose. From standard 12-lead electrocardiograms the maximum and minimum QT intervals (QTmax, QTmin), QTd, corrected QT intervals (QTcmax, QTcmin) and corrected QTd (QTcd) values were calculated at baseline, after the 2nd and the 16th month of carvedilol therapy.

RESULTS

A significant reduction was noted in the QTd and QTcd values with carvedilol therapy after the 16th month (QTd: 81+/-22 ms vs. 40+/-4.3 ms P<0.001; QTcd: 91+/-25 ms vs. 51+/-7 ms P<0.001), but not after the 2nd month (P>0.05). The resting heart rate was also significantly reduced after a 16-month course of carvedilol therapy (78+/-13 bpm vs. 66+/-15 bpm, P<0.05). Carvedilol therapy did not alter QTmax and QTcmax intervals (P>0.05), however, QT min and QTcmin significantly increased with carvedilol at the 16th month (P<0.001 and P<0.01, respectively).

CONCLUSION

Long-term carvedilol therapy was associated with a reduction in QTd, an effect that might contribute to the favorable effects of carvedilol in reducing sudden cardiac death in CHF.

Circadian variation in the effects of aldosterone blockade on heart rate variability and QT dispersion in congestive heart failure

OBJECTIVES

The study was designed to comprehensively evaluate the circadian effects of aldosterone blockade on autonomic tone and QT dispersion in chronic heart failure (CHF).

BACKGROUND

Spironolactone therapy given in addition to angiotensin-converting enzyme inhibitors improved survival in CHF, but the mechanism of its benefit is uncertain. Experimental evidence suggests that aldosterone may have detrimental effects on the autonomic nervous system, especially during the morning hours.

METHODS

Twenty-eight patients with New York Heart Association class II to IV CHF received spironolactone 50 mg daily and placebo for four weeks each in a double-blind crossover fashion. After each treatment phase, a full circadian assessment was undertaken of spironolactone's autonomic effects. The assessment included monitoring heart rate, QT dispersion, continuous Holter recordings, heart rate variability (HRV) and norepinephrine kinetics.

RESULTS

Spironolactone significantly reduced all indices of QT dispersion. The reductions in QTcmax, QTd and QTcd were greatest at 6 AM. In addition, spironolactone had favorable autonomic effects, which were limited to the morning (6-10 AM), including heart rate reduction and an improvement in HRV.

CONCLUSIONS

Spironolactone reduced heart rate and improved HRV and QT dispersion in CHF. Its effects were particularly prominent during the morning hours.

Effect of bisoprolol on QT dispersion in patients with congestive heart failure--the etiology-dependent response

AIMS

To evaluate the effect of beta1-selective blocker bisoprolol on the QT and QTc dispersion in patients with chronic heart failure and to compare the responses to bisoprolol in patients with different etiologies.

METHODS AND RESULTS

Eighty-one patients with heart failure secondary to ischemic heart disease (n=47) or idiopathic dilated cardiomyopathy (n=34) were stratified by etiology and then randomly assigned to the bisoprolol and control group (no tablet) on top of the conventional treatment. QT dispersion was calculated by subtracting the shortest QT from the longest QT, in absolute value (Qtmax-Qtmin). It was also corrected with Bazett's formula (QTc dispersion). After 6 weeks of treatment, QT and QTc dispersion were significantly decreased in the bisoprolol group (QT dispersion: 66.5+/-13.4 ms vs. 49.1+/-16.8 ms for ischemic heart disease (P<0.01); 67.5+/-12.4 ms vs. 59.4+/-14.4 ms for dilated cardiomyopathy (P<0.05); QTc dispersion: 78.3+/-15.2 ms vs. 53.3+/-18.1 ms for ischemic heart disease (P<0.01); 79.1+/-14.2 ms vs. 69.0+/-17.9 ms for dilated cardiomyopathy (P<0.05)), but there was no significant decrease of QT and QTc dispersion in the control group. Linear regression analysis showed that patients with ischemic heart disease tend to have lower 6-week QT dispersion than patients with dilated cardiomyopathy (coefficient beta=-0.283, P=0.009) after controlling for their baseline values in the bisoprolol group.

CONCLUSION

These findings suggested that bisoprolol reduces QT and QTc dispersion in patients with chronic heart failure, but the etiology of heart failure affects the response of patients to bisoprolol.

Effects of antiarrhythmic drugs on QT interval dispersion--relationship to antiarrhythmic action and proarrhythmia

Class IA, IC, and III antiarrhythmic drugs prolong ventricular repolarization (VR) which is manifest as QT interval prolongation on the surface electrocardiogram. These drugs may prolong VR in a spatially heterogeneous manner which results in increased dispersion of VR. This may be manifest as increased QT interval dispersion. Antiarrhythmic drug-induced decreases in QT interval dispersion are associated with antiarrhythmic efficacy in patients with the long QT syndrome and in patients with sustained ventricular tachycardia. Antiarrhythmic drug-induced increases in QT interval dispersion are associated with ventricular proarrhythmia secondary to torsades de points ventricular tachycardia. A number of factors may modulate the effects of antiarrhythmic drugs on dispersion of VR, including the disease state, transient ischemia, electrolyte abnormalities, changes in autonomic tone, and hemodynamic stress.

Electrophysiological basis of QT dispersion measurements

Dispersion of ventricular repolarization is a now widely used term describing nonhomogeneous recovery of excitability or heterogeneity of ventricular repolarization. It is usually expressed as the difference or the range of various repolarization measurements obtained from a heart. Experimentally, an increased dispersion of ventricular repolarization was found to be tightly associated with increased propensity for ventricular arrhythmias, and, therefore, is considered an important arrhythmogenic mechanism. Noninvasively, this arrhythmogenic substrate was approached using multilead body surface potential mapping, but also QT interval dispersion (QTd) and similar electrocardiogram (ECG) variables from the 12-lead surface ECG. Standard QTd from the ECG correlates significantly with dispersion of repolarization measured from the myocardium. A causal relationship is, however, still unclear, and there are 2 main hypotheses to explain the electrophysiological basis of QTd. The local hypothesis explaining QTd with spatial differences in action potential duration mirrored in the various QT intervals competes with the global hypothesis explaining the variation in surface ECG measurements with different projections of a common T-wave vector. Notwithstanding the final explanation for QTd, and particularly for technical reasons, new markers like advanced T-wave loop variables may best reflect the abnormal repolarization substrate on the surface ECG.

Effect of phenylephrine with and without atropine on QT dispersion in healthy normotensive men

The present study examined if changes in cardiac after-load would affect QT interval dispersion. QT dispersion (QTd) on the 12-lead electrocardiogram is believed to be a noninvasive measure of electrical inhomogeneity in the heart and has recently been identified as a sensitive predictor of sudden cardiac death. In experimental models, an increase in cardiac afterload has been shown to alter action potential durations through mechanoelectrical feedback. This may result in an altered dispersion of action potential repolarization in the ventricle. Until now, there has been little evidence for this occurring in man in vivo. In the present study, the effects of afterload on QTd were examined in 10 healthy male volunteers (mean age [SD] 25 years [4.5]) who received an intravenous infusion of phenylephrine (0.2 to 3.6 microg/kg/min) given in incremental doses, and placebo in a blinded, crossover fashion. Because phenylephrine is known to alter heart rate (HR) significantly (via a reflex vagal response), the study was performed with and without atropine. We found a significant positive correlation between acute changes in blood pressure (BP) and changes in all QTd indexes (deltaQTd/delta systolic BP and deltaQTcd/deltasystolic BP r values 0.67 and 0.60, respectively; p <0.001). This relation was independent of HR changes or reflex vagal activity. Atropine had no significant effect on QTd. These observations have important clinical implications and may partly account for why sudden deaths and arrhythmic complications occur so frequently in conditions associated with increased after-load, such as hypertension and heart failure.

QT dispersion is reduced after valve replacement in patients with aortic stenosis

OBJECTIVE

To investigate whether QT dispersion is a reliable index of the severity of aortic stenosis and left ventricular hypertrophy in the setting of aortic stenosis.

DESIGN

A retrospective analysis of the results of echocardiography and electrocardiography before and after aortic valve replacement.

SETTING

Tertiary centre.

PATIENTS

36 men (30 white and six black) with symptomatic aortic stenosis requiring valve replacement.

RESULTS

All patients had significant aortic stenosis (mean (SD) aortic valve area 0.68 (0.18) cm2) and evidence of left ventricular hypertrophy (left ventricular mass index (LVMI): 267 (90) g/m2). Before aortic valve replacement, QT dispersion was correlated with mean aortic valve area and LVMI (r = 0.697, p < 0.001, and r = 0.59, p < 2.4 x 10(-6), respectively). QT dispersion and QT corrected for heart rate dispersion decreased from 133 (54) to 71 (33) ms and from 151 (64) to 94 (76) ms, respectively (p < 0.001 for both). LVMI regressed after aortic valve replacement to 190 (79) g/m2, p < 0.01.

CONCLUSIONS

QT dispersion is increased in association with LVMI in patients with significant symptomatic aortic stenosis. Aortic valve replacement reduces QT dispersion and LVMI. QT dispersion could be a useful indicator of risk and risk reduction in patients with significant symptomatic aortic stenosis.

Ramipril reduces QT dispersion in patients with acute myocardial infarction and heart failure

In a cohort of 67 patients from the Acute Infarction Ramipril Efficacy study, we showed that ramipril therapy was associated with a significant reduction in QT dispersion over a 2-month period after acute myocardial infarction. This reduction of ventricular repolarization inhomogeneity indicates an antiarrhythmic effect and may be an important additional mechanism for the reduced all-cause mortality and sudden death incidence achieved with angiotensin-converting enzyme inhibition after acute myocardial infarction.

QT dispersion in patients with chronic heart failure: beta blockers are associated with a reduction in QT dispersion

OBJECTIVE

To compare QT dispersion in patients with impaired left ventricular systolic function and in matched control patients with normal left ventricular systolic function.

DESIGN

A retrospective, case-control study with controls matched 4:1 for age, sex, previous myocardial infarction, and diuretic and beta blocker treatment.

SETTING

A regional cardiology centre and a university teaching hospital.

PATIENTS

25 patients with impaired left ventricular systolic function and 100 patients with normal left ventricular systolic function.

MAIN OUTCOME MEASURES

QT and QTc dispersion measured by three methods: the difference between maximum and minimum QT and QTc intervals, the standard deviation of QT and QTc intervals, and the "lead adjusted" QT and QTc dispersion.

RESULTS

All measures of QT/QTc dispersion were closely interrelated (r values 0.86 to 0.99; all p < 0.001). All measures of QT and QTc dispersion were significantly increased in the patients with impaired left ventricular systolic function v controls (p < 0.001): 71.9 (6.5) (mean (SEM)) v 46.9 (1.7) ms for QT dispersion, and 83.6 (7.6) v 54.3 (2.1) ms(-1-2) for QTc dispersion. All six dispersion parameters were reduced in patients taking beta blockers (p < 0.05), regardless of whether left ventricular function was normal or impaired-by 9.4 (4.6) ms for QT dispersion (p < 0.05) and by 13.8 (6. 5) ms(-1-2) for QTc dispersion (p = 0.01).

CONCLUSIONS

QT and QTc dispersion are increased in patients with systolic heart failure in comparison with matched controls, regardless of the method of measurement and independently of possible confounding factors. beta Blockers are associated with a reduction in both QT and QTc dispersion, raising the possibility that a reduction in dispersion of ventricular repolarisation may be an important antiarrhythmic mechanism of beta blockade.

Effect of angiotensin converting enzyme inhibition on sudden cardiac death in patients following acute myocardial infarction. A meta-analysis of randomized clinical trials

Estimate the effect of angiotensin converting enzyme (ACE) inhibitors on the risk of sudden cardiac death (SCD) following myocardial infarction (MI).

BACKGROUND

Trials in post-MI patients have shown that ACE inhibitor therapy reduces mortality. However, the effect on SCD as a mechanism has not been clarified.

METHODS

Trials of ACE inhibitor therapy following MI reported between January, 1978 and August, 1997 were identified. Studies were included if they met the following criteria: 1) randomized comparison of ACE inhibitor to placebo within 14 days of MI; 2) study duration/blinded follow-up of > or =6 weeks; 3) the number of deaths and modes of death were reported or could be obtained from the investigators.

RESULTS

We identified 374 candidate articles, of which 15 met the inclusion criteria. The 15 trials included 15,104 patients, 2,356 of whom died. Most (87%) fatalities were cardiovascular and 900 were SCDs. A significant reduction in SCD risk or a trend towards this was observed in all of the larger (N > 500) trials. Overall, ACE inhibitor therapy resulted in significant reductions in risk of death (random effects odds ratio [OR] = 0.83; 95% confidence interval [CI] 0.71-0.97), cardiovascular death (OR = 0.82; 95% CI 0.69-0.97) and SCD (OR = 0.80; 95% CI 0.70-0.92).

CONCLUSIONS

This analysis is consistent with prior reports showing that ACE inhibitors decrease the risk of death following a recent MI by reducing cardiovascular mortality. Moreover, this analysis suggests that a reduction in SCD risk with ACE inhibitors is an important component of this survival benefit.

Irbesartan reduces QT dispersion in hypertensive individuals

Angiotensin type 1 receptor antagonists have direct effects on the autonomic nervous system and myocardium. Because of this, we hypothesized that irbesartan would reduce QT dispersion to a greater degree than amlodipine, a highly selective vasodilator. To test this, we gathered electrocardiographic (ECG) data from a multinational, multicenter, randomized, double-blind parallel group study that compared the antihypertensive efficacy of irbesartan and amlodipine in elderly subjects with mild to moderate hypertension. Subjects were treated for 6 months with either drug. Hydrochlorothiazide and atenolol were added after 12 weeks if blood pressure (BP) remained uncontrolled. ECGs were obtained before randomization and at 6 months. A total of 188 subjects (118 with baseline ECGs) were randomized. We analyzed 104 subjects who had complete ECGs at baseline and after 6 months of treatment. Baseline characteristics between treatments were similar, apart from a slight imbalance in diastolic BP (irbesartan [n=53] versus amlodipine [n=51], 99.2 [SD 3. 6] versus 100.8 [3.8] mm Hg; P=0.03). There were no significant differences in BP normalization (diastolic BP <90 mm Hg) between treatments at 6 months (irbesartan versus amlodipine, 80% versus 88%; P=0.378). We found a significant reduction in QT indexes in the irbesartan group (QTc dispersion mean, -11.4 [34.5] milliseconds, P=0.02; QTc max, -12.8 [35.5] milliseconds, P=0.01), and QTc dispersion did not correlate with the change in BP. The reduction in QT indexes with amlodipine (QTc dispersion, -9.7 [35.4] milliseconds, P=0.06; QTc max, -8.6 [33.2] milliseconds, P=0.07) did not quite reach statistical significance, but there was a correlation between the change in QT indexes and changes in systolic BP. In conclusion, irbesartan improved QT dispersion, and this effect may be important in preventing sudden cardiac death in at-risk hypertensive subjects.

Influence of lead selection and population on automated measurement of QT dispersion

BACKGROUND

The study of QT dispersion (QTd) is of increasing clinical interest, but there are very few data in large healthy populations. Furthermore, there is still discussion on the extent to which QTd reflects dispersion of measurement. This study addresses these problems.

METHODS AND RESULTS

Twelve-lead ECGs recorded on 1501 apparently healthy adults and 1784 healthy neonates, infants, and children were used to derive normal limits of QTd and QT intervals by use of a fully automated approach. No age gradient or sex differences in QTd were seen and it was found that an upper limit of 50 ms was highly specific. Three-orthogonal-lead ECGs (n=1220) from the Common Standards for Quantitative Electrocardiography database were used to generate derived 12-lead ECGs, which had a significant increase in QTd of 10.1+/-13.1 ms compared with the original orthogonal-lead ECG but a mean difference of only 1.63+/-12.2 ms compared with the original 12-lead ECGs. In a population of 361 patients with old myocardial infarction, there was a statistically significant increase in mean QTd compared with that of the adult normal group (32.7+/-10.0 versus 24.53+/-8.2 ms; P<0. 0001). An estimate of computer measurement error was also obtained by creating 2 sets of 1220 ECGs from the original set of 1220. The mean error (difference in QTd on a paired basis) was found to be 0. 28+/-9.7 ms.

CONCLUSIONS

These data indicate that QTd is age and sex independent, has a highly specific upper normal limit of 50 ms, is significantly lower in the 3-orthogonal-lead than in the 12-lead ECG, and is longer in patients with a previous myocardial infarction than in normal subjects.

Regression of left ventricular hypertrophy results in improvement of QT dispersion in patients with hypertension

OBJECTIVES

Increased QT dispersion has been considered as predisposing to ventricular arrhythmias in hypertrophic cardiomyopathy, congestive heart failure, and coronary artery disease. An increased QT dispersion has also been found in hypertensive patients with left ventricular hypertrophy (LVH). The data on the effect of LVH regression on QT dispersion are limited.

METHODS AND RESULTS

To assess the relation of LVH regression and QT dispersion decrease, 68 patients (42 men and 26 women, mean age 56.3+/-9.5 years) with uncomplicated essential hypertension were studied. All underwent full electrocardiographic and echocardiographic studies at baseline and after 6 months of monotherapy, 29 with angiotensin-converting enzyme inhibitors and 39 with calcium antagonists. QT dispersion was calculated by subtracting the shortest QT from the longest QT, in absolute value (QTmax - QTmin). It was also corrected with Bazett's formula (QTc dispersion). Left ventricular mass index was assessed according to the Devereux formula. After treatment, LVH decreased with both angiotensin-converting enzyme inhibitors (from 155 to 130 g/m2, P < .001) and calcium antagonists (156 to 133/92/m2, P < .001). QT dispersion decreased both after angiotensin-converting enzyme inhibitor treatment (from 82 to 63 ms) and calcium antagonist treatment (from 77 to 63 ms, both P < .001 ). There was a significant correlation of QT dispersion and left ventricular mass after therapy (r = 0.36, P < .005). There was a correlation of the degree of LVH and QT dispersion decrease (r = 0.27, P < .05).

CONCLUSIONS

It is concluded that LVH regression influences AQT favorably. Its prognostic value has yet to be determined.

Reduction of QT and QTc dispersion during long-term treatment of systemic hypertension with enalapril

We report, in conjunction with other findings, the evolution of the dispersion of QT and QTc in patients who for the last 7 years have been treated with enalapril for systemic hypertension with left ventricular (LV) hypertrophy. Twenty-four essential hypertensive patients who had received no previous treatment took enalapril (20 mg twice daily) for 7 years. In a pretreatment placebo phase and 8 weeks and 1, 3, 5, 6, and 7 years after the start of therapy, cardiovascular parameters were determined by two-dimensional guided M-mode echocardiography, and the QT interval and corrected QT interval (QTc) and their dispersions were obtained from amplified standard 12-lead electrocardiograms. Therapy rapidly reduced blood pressure (BP) from 156/105 mm Hg to normal values; at 7-year follow-up, BP was 130/84 mm Hg (p <0.001 with respect to the placebo phase). LV mass index decreased progressively until at 5-year follow-up the reduction had reached 39% (p <0.001), after which neither LV mass index nor any structural parameter underwent any further significant change. LV pump function was also significantly better after 7 years of treatment. During this time, QT and QTc decreased significantly, as did the dispersion of both QT (from 61+/-21 to 37+/-14 ms) and QTc (from 67+/-27 to 41+/-16 ms). We conclude that long-term enalapril treatment of hypertensive patients with LV hypertrophy not only induces marked regression of LV mass and improved LV systolic function, but also reduces the dispersions of QT and QTc, which probably reduces the likelihood of ventricular arrhythmias and improves prognosis.