Variability of the QT measurement in healthy men, with implications for selection of an abnormal QT value to predict drug toxicity and proarrhythmia

Morganroth, Joel; Brozovich, Frank V.; McDonald, John T.; Jacobs, Robert A.

doi:10.1016/0002-9149(91)90541-r

Cited by 169 publications

(97 citation statements)

References 7 publications

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“…Different studies used different criteria, such as lead II [1,2,3,4,5,6], lead V5 [6, 10], the lead with the tallest T wave [11], maximum QT in any limb lead [12], maximum QT in all 12 leads [13], mean QT intervals in 12-lead ECG [14, 15], or the mean of the 3 longest QT intervals [8], which might contribute to the discrepant conclusions of otherwise similar studies. Theoretically, the QT interval is considered to represent the duration of electrical systole, namely, the time between first depolarization and last repolarization anywhere in the ventricle.…”

Section: Discussionmentioning

confidence: 99%

An Evaluation of ECG Leads Used to Assess QT Prolongation

Sadanaga¹,

Sadanaga²,

Yao³

et al. 2006

Cardiology

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Aims: The aim of the present study is to elucidate the optimal lead to be selected for the evaluation of drug-induced QT prolongation. Methods and Results: We assessed the validity of each electrocardiography (ECG) lead for the evaluation of QT intervals in 688 patients receiving psychotropic drugs. Abnormal QTc prolongation was observed in 96 (14%) patients using the longest ECG lead. Prevalence of QTc prolongation was larger when using leads I, III, aVR, aVL, aVF, V1, and V6 (>18%), and smaller when using lead V2 (10%). In the remaining 4 ECG leads, the overall accuracy to predict QTc prolongation was higher when using lead V3 (94%) compared with lead II (89%) or lead V5 (90%). Sensitivity to predict QTc prolongation was higher when using lead V4 (81%) compared with lead II (66%) or lead V2 (63%). Conclusion: When a single lead was used for the evaluation of QT prolongation, the results were not always similar to those using the lead which demonstrated the longest QT interval, and if only one lead is to be chosen, lead V3 or V4 should be selected.

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Section: Discussionmentioning

confidence: 99%

An Evaluation of ECG Leads Used to Assess QT Prolongation

Sadanaga¹,

Sadanaga²,

Yao³

et al. 2006

Cardiology

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“…Changes in sympathetic and parasympathetic (autonomic) tone determine these differences. 35,36 In 20 normal subjects, circadian QTc interval variation was 76 ± 19 ms (range, 35-108 ms). 36 Cardiovascular disease may widen this variation.…”

Section: Circadian Variationmentioning

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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“…Morganroth et al 21 found that the average range of QTc over a 24 h period in normal subjects varied from 35±108 ms and that 55% of these subjects had one QTc interval over 440 ms. Molnar et al 22 reported that the mean intrasubject range of QTc was 102 AE 22 ms in females and 88 AE 14 ms in males, being longest immediately after awakening and shortening markedly in the ®rst three hours after awakening. Finally, a recent study from our laboratory indicated meal-related lengthening of QTC intervals in healthy subjects.…”

Section: Technical Considerationsmentioning

confidence: 99%

Electrocardiographic QTc interval: short-term weight loss effects

Pietrobelli

Rothacker²,

Gallagher

et al. 1997

Int J Obes

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OBJECTIVE: Prolongation of the QTc interval is a risk factor for ventricular arrhythmias and sudden death. There is a correlation between body mass index (BMI) and QTc, with longer intervals observed in obese subjects. Dieting and weight loss on selected diets are also associated with prolongation of the QTc interval, although the mechanisms and risk factors of this syndrome are not clearly established. The aim of the current investigation was to determine if short-term weight loss over seven days while living on a metabolic ward in¯uences cardiac repolarization as indicated by QT interval duration. DESIGN AND SUBJECTS: The elctrocardiogram QT, RR, and QTc (QT/RR 0.5 ) intervals were assessed in 30 healthy obese (BMI b 27 kg/m 2 ) men and women ingesting a balanced 1120 kcal/d formula diet (23% kcal as fat and 52 g protein/d). RESULTS: Weight loss (3.9 AE 1.7 kg) over seven days had no measurable effect on the RR interval and there was a signi®cant (P 0.02) shortening of the QT interval (mean AE s.d., 0.395 AE 0.028±0.386 AE 0.027 s) and borderline signi®-cant (P 0.11) shortening of the QTc (0.411 AE 0.028±0.404 AE 0.025 s) interval. The QTc interval normalized in three subjects with prolonged baseline QTc ( b 0.44 s). A statistically signi®cant (P 0.007) reduction in systolic blood pressure early in the course of weight loss (day 2) accompanied the electrocardiographic changes. CONCLUSION: These results fail to support the development of cardiac repolarization abnormalities in obese patients who ingest a nutritionally balanced low calorie diet over seven days. A signi®cant reduction in QT interval duration and amelioration of abnormally prolonged baseline QTc intervals suggest improved cardiac repolarization with early weight loss.

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Variability of the QT measurement in healthy men, with implications for selection of an abnormal QT value to predict drug toxicity and proarrhythmia

Cited by 169 publications

References 7 publications

An Evaluation of ECG Leads Used to Assess QT Prolongation

An Evaluation of ECG Leads Used to Assess QT Prolongation

New Generation Antipsychotic Drugs and QTc Interval Prolongation

Electrocardiographic QTc interval: short-term weight loss effects

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