Correlation Between QTc Prolongation and Obstructive Sleep Apnea in Patients with Type 2 Diabetes Mellitus

Morbid obesity influences the nocturnal electrocardiogram wave and interval durations among suspected sleep apnea patients

BACKGROUND

Obesity is a global issue with a major impact on cardiovascular health. This study explores how obesity influences nocturnal cardiac electrophysiology in suspected obstructive sleep apnea (OSA) patients.

METHODS

We randomly selected 12 patients from each of the five World Health Organization body mass index (BMI) classifications groups (ntotal  = 60) while keeping the group's age and sex matched. We evaluated 1965 nocturnal electrocardiography (ECG) samples (10 s) using modified lead II recorded during normal saturation conditions. R-wave peaks were detected and confirmed using dedicated software, with the exclusion of ventricular extrasystoles and artifacts. The duration of waves and intervals was manually marked. The average electric potential graphs were computed for each segment. Thresholds for abnormal ECG waveforms were P-wave > 120 ms, PQ interval > 200 ms, QRS complex > 120 ms for, and QTc > 440 ms.

RESULTS

Obesity was significantly (p < .05) associated with prolonged conduction times. Compared to the normal weight (18.5 ≤ BMI < 25) group, the morbidly obese patients (BMI ≥ 40) had a significantly longer P-wave duration (101.7 vs. 117.2 ms), PQ interval (175.8 vs. 198.0 ms), QRS interval (89.9 vs. 97.7 ms), and QTc interval (402.8 vs. 421.2 ms). We further examined ECG waveform prolongations related to BMI. Compared to other patient groups, the morbidly obese patients had the highest number of ECG segments with PQ interval (44% of the ECG samples), QRS duration (14%), and QTc duration (20%) above the normal limits.

CONCLUSIONS

Morbid obesity predisposes patients to prolongation of cardiac conduction times. This might increase the risk of arrhythmias, stroke, and even sudden cardiac death.

Sleep Apnea and Cardiovascular Risk in Patients with Prediabetes and Type 2 Diabetes

Obstructive sleep apnea (OSA) is a common but largely undiagnosed clinical condition, which is turning into a serious public health issue. Of note is that its prevalence is gradually increasing in parallel with the obesity and type 2 diabetes mellitus (T2DM) epidemics. The aim of this article is to comprehensively review the literature in order to evaluate the cardiovascular (CV) risk among patients with OSA and prediabetes or T2DM. OSA seems to be an independent risk factor for the development as well as the progression of T2DM, whereas it is associated with T2DM-related macrovascular and microvascular complications. OSA may also act as a potential risk factor for the presentation and development of CV disease, such as hypertension, coronary artery disease, heart failure, pulmonary hypertension, atrial fibrillation and other cardiac arrythmias, as well as stroke. OSA and T2DM also share common pathophysiological mechanisms leading to atherosclerosis. Considering that the coexistence of OSA and T2DM is an independent and cumulative risk factor for CV mortality, more so than the two diseases separately, clinicians and healthcare professionals should be aware of and screen for OSA in patients with T2DM. Notably, targeted therapy for both conditions seems to substantially improve CV prognosis.

Epicardial adipose tissue predicted prolonged QTc interval in patients with arterial hypertension

Introduction: It is important to identify those at higher risk for ventricular arrhythmia among hypertensive patients. Epicardial adipose tissue (EAT) leads to electromechanical changes in the heart by endocrine and paracrine effects with cytokines and mediators. Higher amount of EAT carries the risk of QT prolongation. Therefore, we investigated the association between EAT thickness and QTc interval in patients with arterial hypertension. Methods: A total of 230 patients who previously diagnosed with arterial hypertension between February 2019 to March 2020 were included in the study. Patients with atrial fibrillation, U-wave, atrioventricular block, left anterior or posterior fascicular block, right bundle branch block, left bundle branch block, and taking QT-prolonging medication were excluded. The corrected QT (QTc) interval was calculated with Bazzet's formula following the calculated QT interval in the semi-automatic application tool. EAT was measured at the point on the free wall of the right ventricle using transthoracic echocardiography. Results: The mean age was 62.1 ± 11.4 years and 95 (41.3%) of the patients were male. QTc was over 450 ms were considered as the prolonged interval. Both groups were similar in terms of age (p = .862), gender (p = .265) and other demographic characteristics. Left ventricle mass index (LVMI) (82.5 ± 29.5 vs 91.9 ± 32.6 g/1.7.m², p = .051) and EAT thickness (5.3 ± 2.3 vs 6.6 ± 2.6 mm, p = .001) were higher in the prolonged QTc group. Serum potassium (K) level was lesser in the prolonged QTc group (4.2 ± 0.39 vs 4.1 ± 0.4 mmol/mL, p = .005). Multivariate Cox regression analysis revealed that EAT thickness [OR = 1.227, 95% CI: 1.081-1.393, p = .002] and serum K level [OR = 0.348, 95% CI: 0.157-0.772, p = .009] predicted the prolonged QTc interval, independently. Conclusion: EAT thickness predicted prolonged QTc interval in patients with arterial hypertension. Patients with higher amount of EAT should be followed by closely monitoring to prevent arrhythmic events that may develop in the future. In addition, medications that have a potential effect on QTc interval prolongation may be carefully used in patients with higher EAT thickness.