Relation between QT duration and mortality in an elderly Japanese population

Prevalence, predictors and clinical implications of prolonged corrected QT in elderly patients with dementia and suspected syncope

BACKGROUND

Long QT and use of QT-prolonging drugs are common among older patients receiving polytherapies, but real-world evidence on their impact in clinical practice is controversial. We investigated prevalence, variables associated and clinical implications of prolonged corrected QT (QTc) among patients from the Syncope and Dementia study.

METHODS

Observational, prospective, multicenter study. Patients≥65 years with dementia and fall suspected for syncope in the previous three months were enrolled. Several clinical variables and the complete list of medications were recorded for each patient. A 12‑lead ECG was obtained and corrected QT was calculated by the Bazett's formula. One-year followup for death and recurrent syncope was performed.

RESULTS

Prolonged QTc was observed in 25% of the 432 enrolled patients (mean age 83.3), and was significantly associated with male gender (OR 2.09; 95% CI 1.34-3.26) and diuretics use (OR 1.85; 95% CI 1.18-2.90). At one-year 23.3% of patients died and 30.4% reported at least one recurrent event. Variables associated with one-year mortality were: age, male gender, atrial fibrillation (AF), use of calcium channel blockers and prolonged QTc (OR 1.80; 95% CI 1.01-3.20). Among patients with prolonged QTc a significant interaction for mortality was found with AF. Recurrent events were associated with the use of antiplatelets, cholinesterase. inhibitors and antipsychotics, but not with prolonged QTc.

CONCLUSIONS

We documented a high prevalence of prolonged QTc, that was associated with male gender and diuretics but not with psychoactive medications. Patients with prolonged QTc had higher one-year mortality, that was four-fold increased in those with concomitant AF.

Longitudinal Community-Based Study of QT Interval and Mortality in Southeast Asians

Introduction

The prognostic impact of QT interval prolongation has not been well studied in healthy Asians. We investigated the association between the QT interval with mortality and cardiovascular events in a healthy Southeast Asian population.

Methods

The QT interval corrected for heart rate using the Bazett’s formula (QTc) was measured in 2536 (825 men, mean age 65.7±7.5 years) Singaporean adults free of cardiovascular disease in the population-based Singapore Longitudinal Ageing Study. Outcomes were all-cause mortality and incident cardiovascular events (cardiovascular mortality, myocardial infarction (MI) and/or stroke).

Results

Over a mean 7.78 years (19695 person-years) of follow-up, there were 202 deaths (45 from cardiovascular causes), 62 cases of myocardial infarction and 64 cases of stroke. Adjusting for age, sex, and cardiovascular risk factors, QTcB prolongation remained independently associated with increased all-cause mortality (HR(per standard deviation) 1.27 (1.10–1.48), p = 0.0015), as well as increased risk of cardiovascular events (HR 1.20 (1.01–1.43), p = 0.0415) and MI/stroke (HR 1.22 (1.01–1.47), p = 0.0455), but not cardiovascular mortality alone (HR 1.05 (0.77–1.44), p = 0.7562).

Conclusions

We provide the first community-based estimates of the independent association of QT prolongation with all-cause mortality and cardiovascular events in Southeast Asians.

The genetics of pro-arrhythmic adverse drug reactions

Ventricular arrhythmia induced by drugs (pro-arrythmia) is an uncommon event, whose occurrence is unpredictable but potentially fatal. The ability of a variety of medications to induce these arrhythmias is a significant problem facing the pharmaceutical industry. Genetic variants have been shown to play a role in adverse events and are also known to influence an individual's optimal drug dose. This review provides an overview of the current understanding of the role of genetic variants in modulating the risk of drug induced arrhythmias.

Electrocardiographic QT interval and mortality: a meta-analysis

BACKGROUND

Extremely abnormal prolongation of the electrocardiographic QT interval is associated with malignant ventricular arrhythmias and sudden cardiac death. However, the implications of variations in QT-interval length within normal limits for mortality in the general population are still unclear.

METHODS

We performed a meta-analysis to investigate the relation of QT interval with mortality endpoints. Inverse-variance weighted random-effects models were used to summarize the relative risks across studies. Twenty-three observational studies were included.

RESULTS

The pooled relative risk estimates comparing the highest with the lowest categories of QT-interval length were 1.35 (95% confidence interval = 1.24-1.46) for total mortality, 1.51 (1.29-1.78) for cardiovascular mortality, 1.71 (1.36-2.15) for coronary heart disease mortality, and 1.44 (1.01-2.04) for sudden cardiac death. A 50 milliseconds increase in QT interval was associated with a relative risk of 1.20 (1.15-1.26) for total mortality, 1.29 (1.15-1.46) for cardiovascular mortality, 1.49 (1.25-1.76) for coronary heart disease mortality, and 1.24 (0.97-1.60) for sudden cardiac death.

CONCLUSIONS

We found consistent associations between prolonged QT interval and increased risk of total, cardiovascular, coronary, and sudden cardiac death. QT-interval length is a determinant of mortality in the general population.

QT interval prolongation and the risks of stroke and coronary heart disease in a general Japanese population: the Hisayama study

Uncertainty remains regarding the value of heart-rate-corrected QT interval (QTc) prolongation on electrocardiogram for predicting cardiovascular disease (CVD), particularly among Asian populations. The objective of the present analysis was to analyze the association of QTc prolongation with the development of CVD in a general Japanese population. During the follow-up period, 303 CVD events were observed. Among men, the age-adjusted incidence rates of CVD rose with prolonged QTc levels: 10.9, 12.1, 14.1 and 37.8 per 1000 person-years for subgroups defined by QTc levels of <400, 400-419, 420-439 and > or =440 ms, respectively (P=0.0007 for trend). The risk of CVD in the highest group was 3.09-fold (95% confidence interval, 1.82-5.25) higher than that in the lowest group even after controlling for other confounding factors: age, hypertension, heart rate, electrocardiogram abnormalities, diabetes, impaired glucose tolerance, impaired fasting glycemia, body mass index, total and high-density lipoprotein cholesterols, alcohol intake, smoking habit and regular exercise. Similar associations were observed for the outcomes of stroke and coronary heart disease. Among women, in contrast, no clear associations were found between QTc levels and the risk of CVD events. In conclusion, prolonged QTc levels were associated with the development of CVD among general Japanese men. Measurement of QTc intervals is likely to provide additional information for the detection of individuals at high risk of future CVD events.

Patients with metabolic syndrome have prolonged corrected QT interval (QTc)

BACKGROUND

Prolongation of corrected QT interval (QTc) increases morbidity and mortality and QTc has been found to be longer in patients with diabetes mellitus than in healthy controls. It is still inconclusive whether the metabolic syndrome results in QTc prolongation.

HYPOTHESIS

We hypothesized that metabolic syndrome might contribute to risk of QTc prolongation. The hypothesis was tested in a large population.

METHODS

A total of 5,815 individuals (men: 1,950, women: 3,865 aged 20-80 years) were enrolled. Metabolic syndrome was defined according to the revised third National Cholesterol Education Program Adult Treatment Panel (NCEP-ATP III). QTc was calculated by using Bazett and Fridericia equations and the corrected JT interval (JTc) was derived by subtracting the QRS duration from the QTcB. All individuals had physical examinations, electrocardiograms, echocardiography, and blood tests.

RESULTS

Individuals with metabolic syndrome had longer QTcs and JTc than those without metabolic syndrome (439.84 ms versus 430.90 ms in men, 456.37 ms versus 445.12 ms in women, respectively, p < 0.001 using Bazett formula). The more the number of abnormal metabolic parameters they had, the longer the QTcs and JTc they had. Trend analysis indicated that QTcB, QTcF, and JTc were significantly correlated to the number of abnormal metabolic parameters both in men and in women. After being adjusted for conventional risk factors, QTcB, QTcF, and JTc remained negatively associated with serum potassium concentration and positively associated with interventricular septal thickness.

CONCLUSIONS

Metabolic syndrome is a risk factor for prolonged QTc, which may further increase cardiovascular morbidity and mortality in the subjects with metabolic syndrome.

The prevalence and factors associated with QTc prolongation among emergency department patients

STUDY OBJECTIVE

Previous studies have suggested that QTc prolongation may lead to significant morbidity and mortality. The prevalence of QTc prolongation among emergency department (ED) patients is unknown. The purpose of this study is to determine the prevalence of QTc prolongation among ED patients.

METHODS

This was a retrospective review of ED and inpatient data for all patients with an ECG conducted for any reason at a tertiary care university ED during a 3-month period. QTc prolongation was defined as computer-generated QTc intervals greater than or equal to 450 ms for men and greater than or equal to 460 ms for women.

RESULTS

Of the 1,558 eligible cases, 544 patients had QTc prolongation (35%; 95% confidence interval [CI] 32% to 37%). The prevalence of QTc intervals greater than or equal to 500 ms was 8% (120/1,558; 95% CI 6% to 9%). The most common comorbidities were structural heart disease, renal failure, and stroke. Forty-four percent (239/544; 95% CI 40% to 48%) of patients with any degree of QTc prolongation were discharged from the ED. Furthermore, 23% (28/120; 95% CI 16% to 32%) of patients with QTc intervals greater than or equal to 500 ms were discharged from the ED, including 16 patients with QTc intervals greater than or equal to 500 ms and QRS durations less than 120 ms (16/60; 27%; 95% CI 16% to 40%). Five percent of the patients with QTc prolongation died in the ED or during hospitalization (27/544; 95% CI 3% to 7%); none had QTc prolongation or torsades de pointes listed as a cause of death.

CONCLUSION

QTc prolongation occurred frequently among ED patients who had an ECG study for any reason. Nearly half of all patients with QTc prolongation were discharged from the ED.