Obstructive sleep apnea and temporal changes in cardiac repolarization in patients undergoing coronary artery bypass grafting

STUDY OBJECTIVES

In coronary artery bypass grafting (CABG), abnormal cardiac repolarization is associated with adverse cardiovascular events that can be measured via the QTc interval. We investigated the impact of obstructive sleep apnea on the change in repolarization after CABG and the association of change in repolarization with the occurrence of major adverse cardiac and cerebrovascular events.

METHODS

A total of 1,007 patients from 4 hospitals underwent an overnight sleep study prior to a nonemergent CABG. Electrocardiograms of 954 patients (median age: 62 years; male: 86%; mean follow-up: 2.1 years) were acquired prospectively within 48 hours before CABG (T1) and within 24 hours after CABG (T2). QTc intervals were measured using the BRAVO algorithm by Analyzing Medical Parameters for Solutions LLC. The change in T2 from T1 for QTc (ΔQTc) was derived, and Cox regression was performed.

RESULTS

Compared with those without, patients who developed major adverse cardiac and cerebrovascular events (n = 115) were older and had (1) a higher prevalence of smoking, hypertension, diabetes mellitus, and chronic kidney disease; (2) a higher apnea-hypopnea index and oxygen desaturation index; and (3) a smaller ΔQTc. Cox regression analysis demonstrated a smaller ΔQTc to be an independent risk factor for major adverse cardiac and cerebrovascular events (hazard ratio: 0.997; P = .032). In the multivariable regression model, a higher oxygen desaturation index was independently associated with a smaller ΔQTc (correlation coefficient: -0.58; P < .001).

CONCLUSIONS

A higher preoperative oxygen desaturation index was an independent predictor of a smaller ΔQTc. ΔQTc within 24 hours after CABG could be a novel predictor of occurrence of major adverse cardiac and cerebrovascular events at medium-term follow-up.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Undiagnosed Sleep Apnea and Bypass OperaTion (SABOT); URL: https://classic.clinicaltrials.gov/ct2/show/NCT02701504; Identifier: NCT02701504.

CITATION

Teo YH, Yong CL, Ou YH, et al. Obstructive sleep apnea and temporal changes in cardiac repolarization in patients undergoing coronary artery bypass grafting. J Clin Sleep Med. 2024;20(1):49-55.

Percutaneous mitral commissurotomy versus surgical commissurotomy for rheumatic mitral stenosis: a systematic review and meta-analysis of randomised controlled trials

AIM

Patients with severe mitral stenosis (MS) and their clinicians typically choose percutaneous transvenous mitral commissurotomy (PTMC) over surgical commissurotomy (SC). However, the durability of PTMC relative to SC is uncertain. We compared the efficacy, safety and durability of PTMC with SC for the treatment of MS.

METHODS

We searched EMBASE, MEDLINE and WHO ICTRP registers for randomised controlled trials (RCTs) comparing PTMC, and open and/or closed mitral commissurotomy. The principal outcomes were rate of re-intervention and symptomatic improvement as inferred from the surrogate measures of immediate postprocedural mitral valve area (MVA), MVA at ≥6 month follow-up, incidence of mitral regurgitation (MR) and restenosis. We calculated weighted mean differences (WMD) for continuous outcomes, relative risks (RR) for binary outcomes and pooled outcomes using random-effects models and assessed the quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Seven RCTs with 553 patients proved eligible. Pooled estimates showed no convincing difference in the risk of restenosis or re-intervention (15/100 fewer with PTMC, 95% CI (-20 to +8); quality of evidence: moderate) or in symptoms as inferred from immediate MVA (WMD 0.15, 95% CI (-0.18 to 0.48): very low), from the incidence of postprocedural severe MR (3/100 more with PTMC, 95% CI (-1 to +10): moderate) or from MVA at 30 months.

CONCLUSION

Until data demonstrating convincing superiority of SC over PTMC become available, our results support the current practice of recommending PTMC to young patients with MS and favourable valve morphology, as it is associated with lower peri-procedural morbidity.

PROSPERO REGISTRATION NUMBER

PROSPERO 2017 (CRD42017079512).

The ageing heart: the systemic and coronary circulation

Most cardiovascular disease (CVD) occurs in patients over the age of 60. However, most evidence-based current cardiovascular guidelines lack evidence in an older population, due to the under-representation of older patients in randomised trials. Blood pressure rises with age due to increasing arterial stiffness, and stricter control results in improved outcomes. Myocardial ischaemia is also more common with increasing age, due to a combination of coronary artery disease and myocardial changes. However, despite higher rates of adverse outcomes, older patients are offered guideline-based therapy less frequently. Frailty is an independent predictor of mortality in adults over the age of 60, yet remains poorly assessed; slow gait speed is a key marker for the development of frailty and for adverse outcomes following intervention. Few trials have assessed frailty independent of age; however, there is evidence that non-frail older patients derive significant benefit from therapy, highlighting the urgent need to include frailty as a measure in clinical trials of treatment in CVD.In this review, the authors appraise the literature in regard to the cardiovascular changes with ageing, specifically in relation to the systemic and coronary circulation and with a particular emphasis on frailty and its implication in the evaluation and treatment of CVD.

Forced air warming during sedation in the cardiac catheterisation laboratory: a randomised controlled trial

OBJECTIVE

Forced air warming (FAW) during general anaesthesia is a safe and effective intervention used to reduce hypothermia. The objective of this study was to determine if FAW reduces hypothermia when used for procedures performed with sedation in the cardiac catheterisation laboratory.

METHODS

A parallel-group randomised controlled trial was conducted. Adults receiving sedation in a cardiac catheterisation laboratory at two sites were randomised to receive FAW or usual care, which involved passive warming with heated cotton blankets. Hypothermia, defined as a temperature less than 36°C measured with a sublingual digital thermometer after procedures, was the primary outcome. Other outcomes were postprocedure temperature, shivering, thermal comfort and major complications.

RESULTS

A total of 140 participants were randomised. Fewer participants who received FAW were hypothermic (39/70, 56% vs 48/69, 70%, difference 14%; adjusted RR 0.75, 95% CI=0.60 to 0.94), and body temperature was 0.3°C higher (95% CI=0.1 to 0.5, p=0.004). FAW increased thermal comfort (63/70, 90% vs51/69, 74% difference 16%, RR 1.21, 95% CI=1.04 to 1.42). The incidence of shivering was similar (3/69, 4% vs 0/71 0%, difference 4%, 95% CI=-1.1 to 9.8). One patient in the control group required reintervention for bleeding. No other major complications occurred.

CONCLUSION

FAW reduced hypothermia and improved thermal comfort. The difference in temperature between groups was modest and less than that observed in previous studies where use of FAW decreased risk of surgical complications. Therefore, it should not be considered clinically significant.

TRIAL REGISTRATION NUMBER

ACTRN12616000013460.