Effects of Bariatric Surgery on Heart Rhythm Disorders: a Systematic Review and Meta-Analysis

The aim of this systematic review is to provide an overview of the literature on the effects of bariatric surgery on obesity-associated electrocardiogram (ECG) abnormalities and cardiac arrhythmias. Fourteen studies were included with a methodological quality ranging from poor to good. Majority of the studies showed a significant decrease of QT interval and related measures after bariatric surgery. Seven studies were included in the meta-analysis on effects of bariatric surgery on QTc interval and a significant decrease in QTc interval of - 33.6 ms, 95%CI [- 49.8 to - 17.4] was seen. Bariatric surgery results in significant decrease in QTc interval and P-wave dispersion, i.e., a normalization of initial pathology. The effects on atrial fibrillation are conflicting and not yet fully understood.

Combined effects of exercise training and high doses of anabolic steroids on cardiac autonomic modulation and ventricular repolarization properties in rats

Several studies have reported that high doses of synthetic anabolic androgenic steroids (AAS) can have serious negative effects on health, including the cardiovascular system. The aim of this study was to evaluate the combined effects of AAS and exercise training on ventricular repolarization and cardiac autonomic modulation in rats. Male Wistar rats were allocated into 4 groups: sedentary rats treated with vehicle, sedentary rats treated with nandrolone decanoate, swimming-trained rats treated with vehicle, and swimming-trained rats treated with nandrolone decanoate. Ventricular repolarization was evaluated by electrocardiographic analysis of QT interval and QT dispersion. Cardiac autonomic modulation was assessed by heart rate variability. Our results show that AAS increased QT interval and QT dispersion in sedentary rats treated with nandrolone decanoate as compared to sedentary rats treated with vehicle, indicating AAS-induced ventricular repolarization abnormalities. When rats treated with nandrolone decanoate were subjected to concomitant exercise training, ventricular repolarization was normalized. On the other hand, AAS-induced reduction in cardiac parasympathetic modulation was not prevented by exercise training. In conclusion, AAS produced cardiac autonomic dysfunction and ventricular repolarization disturbances in rats. Combining an exercise training protocol during the AAS treatment attenuated the ventricular repolarization abnormalities and did not prevent cardiac autonomic dysfunction.

Effects of interval training on risk markers for arrhythmic death: a randomized controlled trial

Objective:

To compare the effects of high-intensity interval training versus moderate-intensity continuous training on risk markers of arrhythmic death in patients who recently suffered from an acute coronary syndrome.

Design:

Double-blind (patient and evaluator) randomized controlled trial.

Setting:

Cardiovascular Prevention and Rehabilitation Centre (EPIC Centre) of the Montreal Heart Institute, Montreal, Canada.

Subjects:

A total of 43 patients were randomized following an acute coronary syndrome.

Interventions:

Patients were assigned to either high-intensity interval training (n = 18) or isocaloric moderate-intensity continuous training (n = 19), three times a week for a total of 36 sessions.

Main measures:

Heart rate recovery for 5 minutes, heart rate variability for 24 hours, occurrence of ventricular arrhythmias, and QT dispersion were measured before and after the 36 sessions of training.

Results:

Among the 43 patients randomized, 6 participants in the high-intensity interval training group stopped training for reasons unrelated to exercise training and were excluded from the analyses. Heart rate recovery improved solely in the high-intensity interval training group, particularly at the end of recovery period ( p < 0.05). There were no differences in heart rate variability, occurrence of ventricular arrhythmias, or QT dispersion parameters between the groups at study end.

Conclusion:

Despite the lack of power to detect any large difference between the two interventions with respect to risk markers of arrhythmic death, high-intensity interval training appears safe and may be more effective at improving heart rate recovery relative to moderate-intensity continuous training in our patients following acute coronary syndrome.

Effect of obesity and weight loss on ventricular repolarization: a systematic review and meta-analysis

We performed a systematic review and meta-analysis of the effects of obesity ± overweight and weight loss on the corrected QT interval (QTc) and QT or QTc dispersion (indices of ventricular repolarization). Mean difference for both QTc and QT or QTc dispersion with 95% confidence intervals (CIs) was calculated comparing obese ± overweight subjects and normal weight controls and QTc and QT or QTc dispersion before and after weight loss from diet ± exercise or bariatric surgery. A total of 22 studies fulfilled the selection criteria. Compared with normal weight controls, there was a significantly longer QTc in obese ± overweight subjects (mean difference of 21.74 msec, 95% CI: 18.76 to 22.32) and significantly longer QT or QTc dispersion (mean difference of 15.17 msec, 95% CI: 13.59 to 16.74). Weight loss was associated with a significant decrease in QTc (mean difference -25.77 msec, 95% CI: -28.33-23.21) and QT or QTc dispersion (mean difference of -13.46 msec, 95% CI: -15.60 to -11.32 in obese ± overweight subjects. Thus, obesity ± overweight is associated with significant prolongation of QTc and QT or QTC dispersion. Weight loss in obese ± overweight subjects produces significant decreases in these variables. © 2016 World Obesity.

Exercise-induced ventricular re-polarisation changes in moderate congenital aortic valve stenosis

Introduction Pressure overload increases in patients with moderate aortic valvular stenosis during exercise. In the absence of symptoms, it remains difficult, however, to discriminate patients for surgery based only on pressure overload. Other parameters, such as the dispersion of ventricular re-polarisation (d-QT), which reportedly increases with the transvalvular pressure gradient, have not been fully studied in this condition.

OBJECTIVE

To determine the pattern of QT and d-QT response to exercise testing in children with moderate aortic valve stenosis in order to evaluate the impact of pressure overload from an electrophysiological perspective. Materials and methods In all, 15 patients were compared with 15 controls paired for age (14.8±2.5 versus 14.2±1.5 years old) and gender (66.7% male). All the patients underwent exercise stress testing with 12-lead electrocardiograph recording. QT was measured from the onset of QRS to the apex (QTa) at rest, at peak exercise, and at 1 and 3 minutes upon recovery. QT was corrected using the Fridericia equation, and d-QT was calculated.

RESULTS

Resting QTc was similar among the study groups, but increased significantly in study patients compared with the control group at maximal effort (p=0.004) and after 1 (p<0.001) and 3 (p<0.001) minutes of recovery. A significant association was identified between groups for d-QT (p=0.034), and post-hoc tests revealed a significant difference only at rest (p=0.001).

CONCLUSIONS

Ventricular re-polarisation abnormalities can be unmasked and highlighted by the assessment of electrical re-polarisation during exercise challenge in patients with asymptomatic moderate aortic valve stenosis. Using QT response to exercise could be beneficial for better optimisation of risk stratification in these patients.

Effects of exercise rehabilitation on cardiac electrical instability assessed by T-wave alternans during ambulatory electrocardiogram monitoring in coronary artery disease patients without and with diabetes mellitus

Effects of exercise rehabilitation on electrocardiographic markers of risk for sudden cardiac death have not been adequately studied. We examined effects of controlled exercise training on T-wave alternans (TWA) in 24-hour ambulatory electrocardiogram recordings in patients with stable coronary artery disease (CAD) without and with type 2 diabetes mellitus (DM). Consecutive patients with angiographically confirmed CAD were recruited to join the ARTEMIS (Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection) study. Exercise (n = 65) and control groups (n = 65) were matched on age, sex, DM, and previous myocardial infarction. Ambulatory electrocardiograms were recorded before and after a 2-year training period. TWA was assessed using time domain-modified moving average method by an investigator blinded to patients' clinical status. Average TWA values decreased in the rehabilitation group but not in control patients (rehabilitation [mean ± SEM]: 52.8 ± 1.7 μV vs 48.7 ± 1.5 μV, p <0.001; control: 53.7 ± 1.7 μV vs 54.3 ± 1.6 μV, p = 0.746). Changes in TWA differed between the groups (rehabilitation: -4.1 ± 1.2 μV vs controls: +0.6 ± 1.1 μV, p = 0.005). In CAD + DM patients, 50% (n = 9) of the 18 positive TWA cases were converted with exercise versus 10% (n = 2 of 20) of controls (p = 0.020). In CAD patients, 30% (n = 8 of 27) of positive TWA cases were converted with exercise versus 4% (n = 1 of 28) of controls (p = 0.012). In conclusion, this is the first report of the effectiveness of exercise rehabilitation to reduce TWA, a marker of sudden cardiac death risk, in patients with stable CAD.

The Effects of Metabolic Syndrome on TpTe Interval and TpTe/QT Ratio in Patients with Normal Coronary Arteries

OBJECTIVE

T wave peak to T wave end (TpTe) interval and TpTe/QT have been accepted as predictors of ventricular arrythmia. In this study our aim is to investigate the effect of metabolic syndome on these parameters in patients with angiographically normal coronary arteries.

MATERIALS AND METHODS

Thirty patients with metabolic syndrome (4 male, mean age 52±7.8 years) and twenty patients without metabolic syndrome as control group (8 male, mean age 54±9.3 years) were included. TpTe interval and TpTe/QT ratio were measured from the 12-lead electrocardiogram. These parameters were compared between the groups.

RESULTS

When compared with to the control group the systolic and diastolic blood pressure, pulse pressure, waist circumference, triglyceride and fasting plasma glucose levels were higher and HDL cholesterol level was lower in the metabolic syndrome group. In the analysis of electrocardiography, QT dispersion (QTd) and corrected QTd were significantly increased in metabolic syndrome group as compared to the controls group (44±14 versus 30±12 ms and 433±10 versus 405±4 ms, all p value p=0.01). TpTe interval and TpTe/QT ratio were also significantly higher in patient with metabolic syndrome (112±10 versus 91±10 ms and 0.25±0.02 versus 0.22±0.01, all p value p=0.01).

CONCLUSION

According to these results, we supposed that TpTe/QT ratio and TpTe interval is prolonged and those patients with metabolic syndrome may be at greater risk of ventricular arrhythmias.

Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients

BACKGROUND

QT dispersion (QTd) is a marker of myocardial electrical instability, and is increased in metabolic syndrome (MetS). Moderate intensity continuous exercise (MICE) training was shown to improve QTd in MetS patients.

OBJECTIVES

To describe long-term effects of MICE and high-intensity interval exercise training (HIIT) on QTd parameters in MetS.

METHODS

Sixty-five MetS patients (53 ± 9 years) were assigned to either a MICE (60% of peak power output [PPO]), or a HIIT program (alternating phases of 15-30 s at 80% of PPO interspersed by passive recovery phases of equal duration), twice weekly during 9 months. Ventricular repolarization indices (QT dispersion=QTd, standard deviation of QT = sdQT, relative dispersion of QT = rdQT, QT corrected dispersion = QTcd), metabolic, anthropometric and exercise parameters were measured before and after the intervention.

RESULTS

No adverse events were noted during exercise. QTd decreased significantly in both groups (51 vs 56 ms in MICE, P < 0.05; 34 vs 38 ms in HIIT, P < 0.05). Changes in QTd were correlated with changes in maximal heart rate (r = -0.69, P < 0.0001) and in heart rate recovery (r = -0.49, P < 0.01) in the HIIT group only. When compared to MICE, HIIT training induced a greater decrease in weight, BMI and waist circumference. Exercise capacity significantly improved by 0.82 and 1.25 METs in MICE and HIIT groups respectively (P < 0.0001). Lipid parameters also improved to the same degree in both groups.

CONCLUSION

In MetS, long-term HIIT and MICE training led to comparable effects on ventricular repolarization indices, and HIIT might be associated with greater improvements in certain cardiometabolic risk factors.