Sleep Disordered Breathing and Mortality in Patients With Hypertrophic Obstructive Cardiomyopathy Undergoing Septal Myectomy

Machine learning-based detection of sleep-disordered breathing in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is often concomitant with sleep-disordered breathing (SDB), which can cause adverse cardiovascular events. Although an appropriate approach to SDB prevents cardiac remodelling, detection of concomitant SDB in patients with HCM remains suboptimal. Thus, we aimed to develop a machine learning-based discriminant model for SDB in HCM.

METHODS

In the present multicentre study, we consecutively registered patients with HCM and performed nocturnal oximetry. The outcome was a high Oxygen Desaturation Index (ODI), defined as 3% ODI >10, which significantly correlated with the presence of moderate or severe SDB. We randomly divided the whole participants into a training set (80%) and a test set (20%). With data from the training set, we developed a random forest discriminant model for high ODI based on clinical parameters. We tested the ability of the discriminant model on the test set and compared it with a previous logistic regression model for distinguishing SDB in patients with HCM.

RESULTS

Among 369 patients with HCM, 228 (61.8%) had high ODI. In the test set, the area under the receiver operating characteristic curve of the discriminant model was 0.86 (95% CI 0.77 to 0.94). The sensitivity was 0.91 (95% CI 0.79 to 0.98) and specificity was 0.68 (95% CI 0.48 to 0.84). When the test set was divided into low-probability and high-probability groups, the high-probability group had a higher prevalence of high ODI than the low-probability group (82.4% vs 17.4%, OR 20.9 (95% CI 5.3 to 105.8), Fisher's exact test p<0.001). The discriminant model significantly outperformed the previous logistic regression model (DeLong test p=0.03).

CONCLUSIONS

Our study serves as the first to develop a machine learning-based discriminant model for the concomitance of SDB in patients with HCM. The discriminant model may facilitate cost-effective screening tests and treatments for SDB in the population with HCM.

Prevalence and influence of pulmonary hypertension in patients with obstructive hypertrophic cardiomyopathy undergoing septal myectomy

OBJECTIVES

Pulmonary hypertension (PH) is an independent predictor of all-cause mortality among patients with obstructive and nonobstructive hypertrophic cardiomyopathy (HCM). However, there is little information on the influence of coexisting PH on long-term survival following septal myectomy. This study investigates the prevalence of PH among patients with obstructive HCM undergoing septal myectomy and analyzes patient survival and the course of PH after operation.

METHODS

We included 1342 patients with obstructive HCM who had Doppler echocardiographic estimates of the right ventricular systolic pressure (RVSP) before and after transaortic septal myectomy. PH was defined as RVSP ≥35 mm Hg, with ≥50 mm Hg categorized as moderate-to-severe PH. A multivariable Cox proportional hazards model was used to identify characteristics associated with survival, and longitudinal trends in RVSP were modeled with generalized least squares analysis.

RESULTS

Patients underwent operations from 1989 to 2019. The median age was 57.9 years (interquartile range, 47.4-66.7 years); 49.5% were women. Preoperatively, PH was present in 47.8% of patients, and 14.4% had moderate-to-severe PH. Higher preoperative RVSP was independently associated with overall mortality in the multivariable Cox model. Among patients with moderate to severe preoperative RVSP elevation, postoperative RVSP decreased from baseline by a median of 12 mm Hg.

CONCLUSIONS

Preoperative PH is independently associated with late mortality following septal myectomy, and the magnitude of preoperative RVSP was associated with a postoperative decrease in pulmonary pressure. The influence of PH on late postoperative survival may influence the timing of operation in patients who are candidates for septal myectomy.