Risk For Prolonged QTc Interval Research Articles

Prolonged QTc Interval in Nigerian Children with Sickle Cell Anemia

Prolonged QTc interval, a risk factor for ventricular arrhythmia, occurs in sickle cell anemia. The aim of this study was to determine the risk of prolonged QTc interval and its relationship with vaso-occlusive painful crises (VOCs) and follow-up steady-state in the same children with sickle cell anemia. This prospective cohort study enrolled 38 subjects, aged 5–17 years. History of bone pain and examination were obtained during VOC and steady-state. Assessment of QTc interval was with 12-lead electrocardiography. The QTc interval value >0.440 seconds was taken as prolonged. Median (interquartile range) of QTc interval was higher during VOC [0.447 (0.438–0.459) seconds] than during steady-state [0.435 (0.417–0.440) seconds]. Risk of prolonged QTc interval was higher during VOC (68.4%) than in steady-state (21.1%) with relative risk of 3.250 [95% confidence interval (CI) = 1.692–6.241]. Prolonged QTc interval was likely to occur [area under curve (AUC) = 0.759, p<0.001] during VOC with 68.4% sensitivity, 78.9% specificity and at cutoff point of 0.441 seconds. Prolonged QTc interval negatively correlated with packed cell volume (PCV) during VOC [rs (36) = −0.14, p = 0.387]. Binary logistics of the combined effect of PCV and gender on QTc interval showed that during VOC, males were more likely to have prolonged QTc [odds ratio (OR): 1.337 (95% CI: 0.327–5.464; p = 0.686]. Children with sickle cell anemia, particularly males, were three-times more likely to have prolonged QTc interval during VOC when QTc interval was >0.441 seconds. Routine electrocardiography may help to identify those with QTc intervals above this threshold for prompt cardiac-oriented management.

Prevalence and risk factors of prolonged corrected QT interval in general Chinese population

BackgroundCorrected QT (QTc) interval has been correlated with total and CVD mortality. Although much is known about the relation between prolonged QTc interval and clinical outcome, there is no information on the prevalence and specific risk factors of QTc prolongation in general Chinese population. We evaluated the prevalence of prolonged QTc interval and its risk factors in general Chinese population, aiming to fill in the gaps in the literature and provide evidence for potential CVD risk prediction and disease burden estimate in community.MethodsA population-based survey was conducted on 11,209 participants over the age of 35 in rural areas of Liaoning Province from 2012 to 2013. Twelve-lead ECGs and automatic analysis were performed on all participants. Logistic regression adjustments were made by using the Bazett’s formula to correlate specific risk factors with prolonged QTc intervals (> 440 ms) for potential confounders.ResultsThe overall prevalence of prolonged QTc interval was 31.6%. The prevalence increased significantly with age (24.1% among those aged 35–44 years; 28.3%, 45–54 years; 35.2%, 55–64 years; 43.4%, ≥65 years, P < 0.001). Participants with a history of CVD had a higher prevalence of QTc prolongation (40.7% vs. 30.0%). In the fully adjusted logistic regress model, older age, abdominal obesity, hypertension, diabetes, hypokalemia and any medicine used in the past two weeks were associated independently with increased risk for prolonged QTc interval (All P < 0.05). We found no significant differences between general obesity, hypocalcemia and hypomagnesemia with prolongation of QTc interval. Female sex showed opposite results after applying clinical diagnostic criteria, and high physical activity could reduce the risk of prolonged QTc interval.ConclusionsThe prevalence of prolonged QTc interval was relatively high in general Chinese population and listed relevant factors, which would help identify patients at risk in pre-clinical prevention and provide evidence for estimating potential CVD burden and making management strategies in community.

QTc Interval and Risk of Cardiac Events in Adults With Anorexia Nervosa: A Long-Term Follow-Up Study.

The literature contains several cases of anorexia nervosa (AN) patients with prolonged QTc interval. However, the risk of prolonged QTc interval is controversial and the risk of cardiac events in AN patients has yet to be investigated. We estimated the difference in mean QTc interval and relative risk of borderline prolonged QTc (>440 ms) and prolonged QTc (>460 ms) between 430 adult women AN patients and 123 healthy controls using 3 correction formulas. In a follow-up study, we estimated the risk of a primary end point (a composite of ventricular tachycardia, aborted cardiac arrest, and cardiac arrest) in AN patients compared with a population-based cohort derived from the Danish Civil Register. Mean QTc for AN patients was 408 ms (Hodges), 402 ms (Fridericia), and 399 ms (Bazett). Hodges' found a slightly increased mean QTc (6.8 ms, 95% confidence interval, 1.6-12.0; P=0.01) and percentage with QTc >440 ms in AN patients (relative risk, 3.7, 95% confidence interval, 1.4-10.3; P=0.01), not observed with Fridericia's and Bazett's formulas. There was no difference in the risk of QTc >460 ms between AN patients and healthy controls. During a median follow-up of 10.1 years, AN patients had an increased risk of the primary end point compared with the population-based cohort (hazard ratio, 10.4, 95% confidence interval, 2.6-41.6; P=0.001). However, absolute numbers were small with cumulative incidences of 0.5% and 0.07%, respectively, after 10 years. No events occurred in any AN patient with QTc >440 ms. All-cause mortality was also significantly increased in AN patients compared with the population-based cohort (hazard ratio, 11.2, 95% confidence interval, 5.1-24.5; P<0.001). Overall, there was no difference in mean QTc interval or risk of prolonged QTc between AN patients and healthy controls. However, AN patients had a notably increased all-cause mortality, as well as an increased risk of cardiac events, which was not related to the baseline QTc interval.

Follow-Up (Measurement) of Corrected QT Interval in Adult Patients before and after Lung Transplantation.

Background Prolongation of the corrected QT (QTc) interval is well known for many drugs, some of which are an integral part of the therapeutic regimen after lung transplantation (LTX). Therefore, we investigated the QTc interval after LTX in the present study. Patients and Methods The medical records of patients after LTX were studied for demographic data, indication of LTX, medication, and baseline and follow-up ECGs. The QT interval was corrected for the patient's heart rate using the different formulae of Bazett, Fridericia, Hodges, and Framingham. Results Fifty-nine patients were included. The mean age ± SD was 55.6 ± 7.8 years (median 58 years). After LTX, QTc intervals showed no (relevant) changes during follow-up, even though all patients were treated with drugs (in combination) known to bear a risk of prolonged QTc interval and cortisone. The longest QTc intervals were obtained using Bazett's formula. Conclusion The QTc interval did not increase under immunosuppressive medication after LTX in our cohort of patients. We speculate that the concurrent use of cortisone may shorten the QT(c) intervals or cancel out drug-induced prolongation of the QTc interval.

Sex-specific association between serum uric acid and prolonged corrected QT interval: Result from a general rural Chinese population.

Recently, it has been found that high level of serum uric acid (SUA) is causally related to sudden cardiac death (SCD). We examined the sex-specific associations of SUA with prolonged heart rate-corrected QT (QTc) interval in a general Chinese population.A large sample of 11,206 Chinese research participants aged 35 years and older was recruited from rural areas of Liaoning Province during 2012 to 2013. SUA were divided into quartiles separated for males and females. Prolonged QTc interval, assessed by the Bazett formula, was defined as cut points of 460 ms or longer in females and 450 ms or longer in males. Mean (+/− standard deviation) QTc intervals were 422.1 ± 24.2 ms among 5104 males and 436.1 ± 23.5 ms among 6102 females, respectively. In both sexes, SUA showed significant correlations with QTc interval (both P < 0.001). Among male participants, the highest quartile of SUA (>379 μmol/L) was related to an increased risk for prolonged QTc interval (odds ratios: 1.402, 95% confidence interval: 1.073–1.831) compared to the lowest quartile (≤276 μmol/L) after fully adjustment. However, there were no significant relationships between SUA and prolonged QTc interval among females in all the models.Males with high SUA are prone to a higher risk for prolonged QTc interval. This study provides novel explanation for population-based findings on SUA and SCD, as well as important implications for management strategies for hyperuricemic patients in clinical practice.

Relation of Heavy Alcohol Consumption to QTc Interval Prolongation

Until now, few studies have examined QT intervals in subjects who consume alcohol. We performed this study to evaluate the associations between alcohol consumption and the QTc interval based on a general population. A total of 11,269 adults were examined using a multistage cluster sampling method to select a representative sample of subjects aged ≥35years. Participants were asked to provide information about their alcohol consumption, and all participants received electrocardiograms and echocardiograms. A prolonged QTc interval was defined according to the national guidelines, which specify thresholds of ≥460ms in women and ≥450ms in men. Patients were divided into 3 categories, based on the amount of alcohol they consumed: heavy drinkers (>15g/day for women and >30g/day for men), moderate drinkers (≤15g/day for women and ≤30g/day for men), and nondrinkers (0g/day). The results showed that the heavy drinkers had longer QTc intervals than did the nondrinkers. Multivariate logistic regression analyses revealed that men who were heavy drinkers had approximately 1.4-fold higher odds of having a prolonged QTc interval (odds ratio 1.431, 95% confidence interval [CI] 1.033 to 1.982, p= 0.031) than nondrinkers; in women, heavy drinkers had ∼2.3-fold higher odds of having a prolonged QTc interval (odds ratio 2.344, 95% CI 1.202 to 4.571, p= 0.012) than nondrinkers. Neither men nor women who were moderate drinkers exhibited a significant increase in risk for prolonged QTc interval. In conclusion, heavy alcohol consumption was found to be a risk factor for a prolonged QTc interval.

Domperidone-Associated QT Interval Prolongation in Non-oncologic Pediatric Patients: A Review of the Literature.

Domperidone is a prokinetic agent used to treat pediatric gastroesophageal reflux disease. Health Canada has issued warnings about an increased risk of domperidone-associated ventricular arrhythmias and sudden cardiac death. However, the supporting data referred only to adult patients; therefore, extrapolating the safety risks to pediatric patients is difficult. To summarize and evaluate the evidence for domperidone-associated QT interval prolongation, ventricular arrhythmias, and sudden cardiac death to determine the safety of this drug for pediatric patients. Two databases (MEDLINE [1946 to August 2015] and Embase [1980 to August 2015]) were searched with the following Medical Subject Headings and keywords: "domperidone", "arrhythmias, cardiac", "death, sudden, cardiac", "electrocardiography", "heart diseases", "long QT syndrome", "tachycardia, ventricular", "torsades de pointes", and "ventricular fibrillation". The search was limited to studies conducted in humans under 18 years of age and published in English. Original research included in this review reported on the cardiac-related safety of domperidone in nononcologic patients under 18 years of age. Of the 5 studies meeting the inclusion criteria (n = 137 patients), one reported a statistically significant change in the corrected QT (QTc) interval, but the clinical significance was unclear. Most of the studies reported rare occurrences of pathological QTc intervals in a limited number of patients. However, confounding factors (e.g., abnormal electrolyte level or concurrent medications) were not consistently considered. Potential bias might have been alleviated by blinding of electrocardiogram (ECG) assessors; however, this was not consistently implemented. The designs of the included studies did not allow assessment of causality. The results should be interpreted with caution. Although the available evidence is limited, pathological QTc intervals were noted among a small number of infants, which supports the possibility of domperidone-associated risk of prolonged QTc interval. Because of the potential severity of QT interval prolongation, individual assessment and routine ECG monitoring should be implemented for patients receiving domperidone.

Children and adolescents with type 1 diabetes mellitus have a sixfold greater risk for prolonged QTc interval

QT-wave abnormalities have been detected in type 1 diabetes mellitus (T1DM). Prolongation of the heart rate corrected QT interval (QTc) has been associated with cardiovascular mortality. We evaluated how often QT/QTc abnormalities are present in youth with T1DM and if they are associated with disease parameters. Sixty-two T1DM youngsters and equal age- and gender-matched controls were studied. Demographic, anthropometric, and laboratory data were determined. QT was measured on a 12-lead resting electrocardiogram. QTc was calculated using Bazett's formula. T1DM patients had significantly longer QT/QTc than controls, but significance disappeared after adjustment for confounders. Abnormally prolonged QTc≥440 ms was observed six times more frequently in those with T1DM. QT was correlated with age, age at disease onset, but not with glycated hemoglobin or diabetes duration; QTc was only correlated with pubertal stage. T1DM youths have a sixfold increased risk for QT/QTc prolongation and should have regular follow-up for cardiac autonomic dysfunction.

Pharmacotherapeutic Determinants for QTc Interval Prolongation in Japanese Patients with Mood Disorder

An increased incidence of sudden death has been observed among patients treated with antidepressants. A prolonged QTc interval is a known prognostic factor for fatal arrhythmia, and several studies have shown that the use of antidepressants can cause a prolonged QTc interval. However, few studies, especially in Japan, have compared the effects of multiple drugs on QTc interval or examined dose relationships in a clinical setting.We compared the effects of antidepressants on QT interval, corrected to QTc by Bazett's formula, in 729 Japanese patients who were diagnosed with mood disorder.Using stepwise multiple linear regression analysis, we found that the use of tricyclic antidepressants (P<0.01) and concomitant use of antipsychotics (P<0.05), as well as advanced age and being female (known factors for prolonged QTc interval; both P<0.01), significantly prolonged the QTc interval. Analysis of individual antidepressants also revealed that the use of clomipramine (P<0.01) and amitriptyline (P<0.05) significantly prolonged the QTc interval.Our results reveal that tricyclic antidepressants, especially clomipramine and amitriptyline, confer a risk of prolonged QTc interval in a dose-dependent manner. The selective serotonin reuptake inhibitors investigated (fluvoxamine, paroxetine, sertraline) were not indicated as risk factors for QTc prolongation.

Dialysate bath and QTc interval in patients on chronic maintenance hemodialysis: pilot study of single dialysis effects

Serum concentrations of potassium (K) and calcium (Ca) influence ionic currents and play an important role in the duration of ventricular action potential. Further, the influence of alkalosis in reducing ionized calcium has been well known for a long time. The aim of this study was to assess the effects of different dialysate electrolytes and bicarbonate concentrations on changes of QTc interval in patients on chronic hemodialysis. The study hemodialysis sessions were performed in 22 patients, with different electrolyte and bicarbonate concentrations in dialysate. Tested dialysate concentrations were K of 2 and 3 mmol/L; Ca 1.25, 1.5 and 1.75 mmol/L; and bicarbonate 30 and 34 mmol/L. An electrocardiogram (ECG) was recorded 1 hour before, at the end and every hour for 4 hours after each study dialysis session. QTc interval was measured from the beginning of the QRS complex to the end of a T wave on a 12-lead ECG. Blood was collected and K, total Ca, ionic Ca and pH evaluated. At the end of the study hemodialysis session with dialysate containing low K (2 mmol/L), low Ca (1.25 mmol/L) and high bicarbonate concentration (34 mmol), mean QTc interval was significantly prolonged compared with that recorded with dialysate containing high K (3 mmol/L), high Ca (1.75 mmol/L) and bicarbonate (30 mmol) (40 ± 10 milliseconds vs. 2 ± 2 milliseconds; p<0.01). Dialysate with low concentration of low Ca, K and high concentration of bicarbonate was an independent predictor of QTc; the combination of low Ca and K and high bicarbonate strongly increased the risk of prolonged QTc interval. The present pilot study shows that changes in QTc interval during hemodialysis depend on both electrolyte and bicarbonate concentrations in dialysate.