The QT interval

Bednar, Martin M.; Harrigan, E.P.; Anziano, Richard J.; Camm, A. John; Ruskin, Jeremy N.

doi:10.1053/pcad.2001.21469

Cited by 161 publications

(172 citation statements)

References 277 publications

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“…The authors recommended the use of the mean of several available recordings, which were not available in the present study. Heart rate-corrected QT duration is controlled in part by sympathetic nerve activity (37). Longer QT intervals, representing higher sympathetic activity, have been related to glucose and insulin in cross-sectional studies (38).…”

Section: Limitations Of Ecg Measurementsmentioning

confidence: 99%

The Association Among Autonomic Nervous System Function, Incident Diabetes, and Intervention Arm in the Diabetes Prevention Program

et al. 2006

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OBJECTIVE -Autonomic nervous system dysfunction, a correlate of obesity and poor cardiorespiratory fitness, is associated with the development of diabetes. We tested whether estimates of autonomic nervous system function improved in the intensive lifestyle versus metformin or placebo arms of the Diabetes Prevention Program (DPP) and whether baseline or a change in autonomic nervous system function was associated with the development of diabetes over 3.2 years.RESEARCH DESIGN AND METHODS -In 2,980 DPP participants, 12-lead electrocardiograms were measured at baseline and annually. Heart rate, heart rate variability (HRV), and QT duration were used to estimate fitness and autonomic nervous system function.RESULTS -In the lifestyle arm, heart rate and QT indexes decreased, and HRV increased over time. The magnitude of decline in heart rate and QT duration was substantially smaller in the other arms, whereas HRV did not increase. Baseline heart rate was the only index significantly (P Ͻ 0.05) associated with incident diabetes after adjustment for demographics and weight change (hazard ratio for lifestyle and metformin arms ϭ 1.19 and 1.17 per 10.6 beats/min, respectively). Decreases in heart rate and QT indexes and increases in HRV over time were associated with a lower risk of developing diabetes. The protective association between decreased heart rate and incident diabetes in the lifestyle arm remained significant after accounting for change in weight and physical activity.CONCLUSIONS -Indexes that reflect autonomic function and fitness improved (i.e., heart rate decreased and HRV increased) in the lifestyle modification arm of the DPP. Improvements in these indexes are inversely associated with the development of diabetes independent of weight change. Diabetes Care 29:914 -919, 2006A utonomic impairment has been identified at the time of diabetes diagnosis, which suggests that impairment may be present after a relatively brief exposure to hyperglycemia or develop in conjunction with obesity or insulin resistance (1,2). Cross-sectional studies in adults without diabetes provide evidence that markers of autonomic functioning are inversely associated with obesity, insulin resistance, and fasting glucose (3-6). Recent research suggesting that autonomic dysfunction predicts the development of diabetes (7,8) supports the long-held clinical suspicion that autonomic dysfunction is associated with the development of diabetes in healthy adults (9).Adults were identified as eligible to participate in the Diabetes Prevention Program (DPP) because they were at risk for developing diabetes, most commonly because of existing hyperglycemia and obesity. Thus, it is plausible that many had existing autonomic impairment at baseline in the study. At the conclusion of the trial, there was a significantly lower incidence of diabetes in the intensive lifestyle modification arm compared with that in the metformin or placebo arms (10). Lifestyle modification involved increasing physical activity and lowering dietary fat intake with a goa...

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Section: Limitations Of Ecg Measurementsmentioning

confidence: 99%

The Association Among Autonomic Nervous System Function, Incident Diabetes, and Intervention Arm in the Diabetes Prevention Program

et al. 2006

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“…When the QTc interval is greater than 500 ms, the patient is at an increased risk of developing torsades de pointes. 4 Zareba et al 30 reported that the risk of cardiac events before age 40 years in family members with congenital long QT syndrome (LQTS) not taking β-blockers was influenced by the QTc interval. The odds ratio was 2.18 in family members with a QTc interval > 440 ms to 460 ms, 3.93 with a QTc interval > 460 ms to 500 ms, and 9.66 with a QTc interval > 500 ms. Figure 2 shows the action potential of a single ventricular muscle cell.…”

Section: Electrocardiographic Qt Intervalmentioning

confidence: 99%

“…4 The most common QT interval or QTc is 600 to 649 ms among patients with torsades de pointes. 4 (Table 1) …”

Section: Torsades De Pointesmentioning

confidence: 99%

New Generation Antipsychotic Drugs and QTc Interval Prolongation

Vieweg

2003

Prim. Care Companion CNS Disord.

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Background: Recent regulatory and clinical concerns have brought into sharp focus antipsychotic drug-induced QTc interval prolongation, torsades de pointes, and sudden cardiac death. Several new generation (atypical) antipsychotic drugs have either been withdrawn from clinical use or delayed in reaching the marketplace due to these concerns. Because torsades de pointes is rarely found, QTc interval prolongation serves as a surrogate marker for this potentially life-threatening arrhythmia. Current methods of calculating this electrocardiographic parameter have limitations. The primary care physician is a key member of the team managing a patient who requires administration of antipsychotic drugs. This article focuses on new generation antipsychotic drugs and principles useful to both the primary care physician and the psychiatrist.Method: PubMed was searched in September 2002 using the terms antipsychotic drug and QT interval. References were examined from review articles describing antipsychotic drugs and the QT interval. The author's files gathered over the past 20 years on the QT interval were also reviewed.Results: Nine cases were available in which druginduced QTc interval prolongation was associated with new generation antipsychotic drug administration. Eight cases were taken from the literature, and the author added one additional report. The newer agents involved were risperidone, quetiapine, and ziprasidone. In at least 8 cases, there was evidence of other risk factors associated with QTc interval prolongation. In one case frequently referenced in the literature, the authors misunderstood their own data showing that QTc interval prolongation did not relate to delayed ventricular repolarization. In another instance, 2 authors reported on the same patient, with important information missing from both articles. No evidence of torsades de pointes appeared in any of the 9 cases.Conclusions: No evidence is currently available in the literature implicating new generation antipsychotic drugs in the production of torsades de pointes. However, the absence of such evidence does not prove that newer antipsychotic drugs do not cause torsades de pointes. Among patients free of risk factors for QTc interval prolongation and torsades de pointes, current literature does not dictate any specific consultative or laboratory intervention before administering new generation antipsychotic drugs. When risk factors are present, evaluation and intervention specific to those risk factors should dictate the clinician's course of action. More specific guidelines for monitoring the QT interval and risk of torsades de pointes await improved methods of measuring the QTc interval relevant to each patient.(Primary Care Companion J Clin Psychiatry 2003;5:205-215)

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“…Prolonged cardiac repolarization is associated with the development of fatal arrhythmias and the occurrence of SCD [6,7,8]. Different measures derived from electrocardiography (ECG) represent repolarization inhomogeneities of the myocardium such as QT interval and QT dispersion [8,9].…”

Section: Introductionmentioning

confidence: 99%

Chronic Obstructive Pulmonary Disease and Cardiac Repolarization: Data from a Randomized Controlled Trial

2016

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Background: Altered cardiac repolarization is a risk factor for sudden cardiac death and seems to be increased in chronic obstructive pulmonary disease (COPD) patients. Objective: Lung volume reduction surgery (LVRS) has been shown to improve breathing mechanics and lung function in patients with severe COPD and emphysema and possibly also improve altered cardiac repolarization. Methods: Thirty patients scheduled for LVRS were randomized to LVRS or to the control group. We investigated the treatment effect 3 months after LVRS on measures of cardiac repolarization and dispersion of repolarization (QTc interval, QT dispersion) derived from electrocardiography. Univariable and multivariable analyses were used to identify possible confounders influencing the treatment effect. Results: LVRSwas associated with an improvement in lung function (mean ± SD residual volume/total lung capacity of -9 ± 11% and forced expiratory volume in 1 s of +30 ± 29%). LVRS did not significantly reduce QTc (median -5.3 ms, 95% confidence interval, CI -15.5 to 3.7, p = 0.214) and QT dispersion (median -3.0 ms, 95% CI -13.0 to 7.0, p = 0.536) compared to the control group. No significant association between change in QTc and change in QT dispersion, respectively, and change in possible confounders was found. Conclusion: LVRS seems to have no effect on cardiac repolarization in patients with COPD. Thus, lung hyperinflation seems not to be a causal mechanism for altered cardiac repolarization in COPD patients.

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The QT interval

Cited by 161 publications

References 277 publications

The Association Among Autonomic Nervous System Function, Incident Diabetes, and Intervention Arm in the Diabetes Prevention Program

The Association Among Autonomic Nervous System Function, Incident Diabetes, and Intervention Arm in the Diabetes Prevention Program

New Generation Antipsychotic Drugs and QTc Interval Prolongation

Chronic Obstructive Pulmonary Disease and Cardiac Repolarization: Data from a Randomized Controlled Trial

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