The Myth of QT Shortening by Weight Loss and Physical Training in Obese Subjects With Coronary Heart Disease

Gondoni, Luca Alessandro; Titon, Anna Maria; Montano, Mariella; Caetani, Giulia; Nibbio, Ferruccio; Schwartz, Peter J.

doi:10.1038/oby.2010.132

Cited by 6 publications

(6 citation statements)

References 31 publications

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“…These authors also observed that rate-corrected QT (QTc) was not changed by pregnancy and so concluded that the duration of ventricular repolarisation is entirely rate-dependent. Gondoni et al (2011) found a strong relationship between ejection fraction and QTc and since it is well documented that ejection fraction is unaltered with pregnancy (Capeless & Clapp, 1989), this may explain the unaltered QTc with gestation. We have extended these observations by showing that uncorrected QTe and QTa are significantly reduced even by the end of the first trimester and notably in all physiological states.…”

Section: Discussionmentioning

confidence: 71%

Changes in heart rate variability and QT variability during the first trimester of pregnancy

et al. 2015

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The risk of new-onset arrhythmia during pregnancy is high, presumably relating to changes in both haemodynamic and cardiac autonomic function. The ability to non-invasively assess an individual's risk of developing arrhythmia during pregnancy would therefore be clinically significant. We aimed to quantify electrocardiographic temporal characteristics during the first trimester of pregnancy and to compare these with non-pregnant controls. Ninety-nine pregnant women and sixty-three non-pregnant women underwent non-invasive cardiovascular and haemodynamic assessment during a protocol consisting of various physiological states (postural manoeurvres, light exercise and metronomic breathing). Variables measured included stroke volume, cardiac output, heart rate, heart rate variability, QT and QT variability and QTVI (a measure of the variability of QT relative to that of RR). Heart rate (p < 0.0005, p < 0.0005, p < 0.0005) and cardiac output (p = 0.043, p < 0.0005, p < 0.0005) were greater in pregnant women in all physiological states (respectively for the supine position, light exercise and metronomic breathing state), whilst stroke volume was lower in pregnancy only during the supine position (p < 0.0005). QTe (Q wave onset to T wave end) and QTa (T wave apex) were significantly shortened (p < 0.05) and QTeVI and QTaVI were increased in pregnancy in all physiological states (p < 0.0005). QT variability (p < 0.002) was greater in pregnant women during the supine position, whilst heart rate variability was reduced in pregnancy in all states (p < 0.0005). Early pregnancy is associated with substantial changes in heart rate variability, reflecting a reduction in parasympathetic tone and an increase in sympathetic activity. QTVI shifted to a less favourable value, reflecting a greater than normal amount of QT variability. QTVI appears to be a useful method for quantifying changes in QT variability relative to RR (or heart rate) variability, being sensitive not only to physiological state but also to gestational age. We support the use of non-invasive markers of cardiac electrical variability to evaluate the risk of arrhythmic events in pregnancy, and we recommend the use of multiple physiological states during the assessment protocol.

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Section: Discussionmentioning

confidence: 71%

Changes in heart rate variability and QT variability during the first trimester of pregnancy

et al. 2015

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“…Many studies that followed showed that obesity can cause prolonged QTc interval [9][10][11]. Much of comorbidities associated with obesity can be improved or prevented with body weight (BW) reduction [12]. Effects of changes in body mass index (BMI) on cardiovascular risk are verified in the Framingham study.…”

Section: Introductionmentioning

confidence: 99%

“…Many studies observed the effects of weight reduction on the QTc interval in obese patients, but the results are conflicting. The most of the studies observed that QTc interval is shortening during the weight reduction [14][15][16][17], but some studies haven't shown significant changes in the QTc interval during weight reduction [12,18]. It is surely important to monitor the QTc interval during the treatment of obesity in order to prevent adverse cardiovascular events.…”

Section: Introductionmentioning

confidence: 99%

Body Weight Reduction and QTc Interval in Obesity

Milovančev¹,

Stokić²,

Popovic³

et al. 2016

Adv Weigh Loss Manag Med Dev

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Introduction: Obesity is associated with wide variety of electrocardiographic (ECG) abnormalities. Prolonged QTc interval is common in obesity and it represents a delayed ventricular repolarisation which is associated with ventricular arrhythmias, syncope and sudden cardiac death. The aim of our study is to evaluate the effects of weight reduction on QTc interval in obese subjects. Materials and Methods: The study included 74 obese subjects aged 41.78 ± 10.70 years, treated with a lowcalorie diet (800 kcal/day) for two weeks. All patients underwent a standard resting 12-lead surface ECG before and after the treatment. QTc intervals were corrected by Bazett's formula. Results: The average loss in body weight was 10.26 ± 3.63%, and the average reduction in body mass index was 9.39 ± 4.23%. There were statistically significant differences for all electrocardiographic parameters (p<0.01) except for the QTc dispersion (p>0.05) before and after the treatment with low-calorie diet. Heart rate was also statistically significant reduced after the low-calorie diet treatment. Prevalence of prolonged QTc interval was 24.32% before and 9.21% after the treatment. Conclusion: The results show that obesity causes prolongation of QTc interval. Significant weight reduction of about 10% leads to favorable electrocardiographic changes and significant shortening of the QTc interval.

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“…Indeed, the Bazett equation is known to be most sensitive to biasing effects of HR which appear to be particular important in the context of weight loss since weight loss is often accompanied by a reduction in HR. It should be noted, however, that the extent of weight loss induced by a hypocaloric diet and exercise in the abovementioned negative study [9] was only moderate, i.e. a BMI reduction of −1.2 kg m −2 .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, weight loss, in particular when induced by bariatric surgery, has been found to reduce QT interval (QTc) length in many studies (for overview see Table 1) [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. However, the validity of this observation has been challenged by one previous study [9] that demonstrated that the significance of QTc shortening upon weight loss gets lost when the QT interval is corrected for heart rate (HR) by using Fridericia or Framingham correction equation instead of the most commonly used Bazett equation. Indeed, the Bazett equation is known to be most sensitive to biasing effects of HR which appear to be particular important in the context of weight loss since weight loss is often accompanied by a reduction in HR.…”

Section: Introductionmentioning

confidence: 99%

QT Interval Shortening After Bariatric Surgery Depends on the Applied Heart Rate Correction Equation

et al. 2016

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Background A shortening of electrocardiographic QT interval has been observed in obese subjects after weight loss, but previous results may have been biased by inappropriate heart rate (HR) correction. Methods Electrocardiography (ECG) recordings of 49 (35 females) severely obese patients before and 12 months after Roux-en-Y gastric bypass (RYGB) surgery were analysed. QT interval (QTc) was calculated by using four different equations, i.e. Bazett, Fridericia, Framingham and Hodges. Results Irrespectively of the used correction formula, QTc interval length was reduced after the surgery (QTc Bazett −31 ± 18 ms; QTc Fridericia −12 ± 15 ms; QTc Framingham −14 ± 15 ms; QTc Hodges −9 ± 15 ms; all Ps < 0.001), but QTc Bazett reduction was significantly greater than the reduction in QTc calculated upon the other three equations (all Ps < 0.001). Moreover, changes in QTc Bazett (P < 0.001) but not in QTc Fridericia , QTc Framingham and QTc Hodges (all Ps > 0.05) were significantly correlated with concurrent changes in HR. Multivariate regression analyses revealed a significant independent association of serum insulin levels with QTc Fridericia , QTc Framingham and QTc Hodges values (all Ps < 0.05) preoperatively, whilst changes in QTc interval length after the surgery were not consistently associated to concurrent changes in metabolic traits. Conclusions Our data show that the extent of weight lossassociated QTc interval shortening largely depends on the applied HR correction equation and appears to be overestimated when the most popular Bazett's equation is used.

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The Myth of QT Shortening by Weight Loss and Physical Training in Obese Subjects With Coronary Heart Disease

Cited by 6 publications

References 31 publications

Changes in heart rate variability and QT variability during the first trimester of pregnancy

Changes in heart rate variability and QT variability during the first trimester of pregnancy

Body Weight Reduction and QTc Interval in Obesity

QT Interval Shortening After Bariatric Surgery Depends on the Applied Heart Rate Correction Equation

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