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

Abstract

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.

QT Interval Shortening After Bariatric Surgery: Mind the Heart Rate Correction Equation

“…We have previously reported on electrocardiography (ECG) recordings analysis of 49 (35 females) patients with severe obesity before and 12 months after Roux-en-Y gastric bypass (RYGB) surgery [2]. Similar to Sanches et al we found a QTc interval length reduction of (mean ± standard deviation) − 31 ± 18 ms when we used the most frequently applied Bazett equation for heart rate correction.…”

The incidence of cardiac arrhythmias during exercise stress testing: a focus on patients with severe obesity undergoing sleeve gastrectomy

“…19 Moreover, several studies showed that patients with obesity have a prolonged QT interval, highlighting the effects of bariatric surgery on reducing QTc. [20][21][22] In our study, resting HR and QTc interval were found signi cantly decreased at six months post SG and further changes are not evident one year after bariatric surgery. The relationship between obesity and prolonged ventricular repolarization is not clearly understood and various hypotheses have been proposed.…”

The negative effects of obesity on heart, especially the electrophysiology of the heart

“…In patients undergoing sleeve gastrectomy, P wave dispersion (PWD) and QTd values were shown to be weakened [95], and QTc was shortened [96]. Similarly, shorter QTc was shown after jejunal Roux-en-Y gastric bypass surgery [97]. A decrease in heart rate variability (HRV) and QT variation index (QTVI) after laparoscopic gastric banding (LGB) and biliarypancreatic shunt (BPD) indicated an improvement in autonomic nervous system (ANS) dysfunction in OP [98].…”