Konecny, Thomas

Importance Sleep disordered breathing (SDB) is a well-established contributor to cardiovascular morbidity, mediated by intermittent hypoxemia, autonomic dysregulation, and endothelial dysfunction. Patients with hypertrophic cardiomyopathy (HCM) may be especially at risk for SDB, but the clinical impact of SDB in this population remains unclear. Objective To define the prevalence and subtypes of SDB in HCM and examine their association with echocardiographic parameters and cardiac biomarker expression. Design, Setting, and Participants A prospective cohort study was conducted between April 18, 2018, and January 15, 2024, at a single tertiary referral center specializing in HCM care. Adults with HCM (left ventricular wall thickness ≥15 mm or pathogenic variants) were recruited from an institutional registry. Patients diagnosed with SDB or current pregnancy were excluded. Patients underwent polysomnography, with comparative assessment of echocardiographic, electrocardiographic, and biomarker indices. Observers were blinded to polysomnographic results. Data analysis was performed from April 11, 2024, to July 25, 2024. Exposures SDB classified via polysomnography using apnea-hypopnea index thresholds, with subtypes including obstructive sleep apnea and central sleep apnea and with event severity, hypoxemia, and sleep architecture disruption quantified. Main Outcomes and Measures Echocardiographic indices, cardiac biomarker expression, functional status, apnea-hypopnea index, and overnight hypoxemia. Results Among 154 patients (median [IQR] age, 60 [48-68] years; 102 [66.2%] male), 91 (59.1%) were diagnosed with SDB. Those with SDB, compared with those without SDB, had higher left ventricular mass index (median [IQR], 128 [107-161] vs 109 [96-134] g/m 2 ; P = .03), E/e′ ratio (median [IQR], 12.5 [10.0-15.0] vs 10.0 [8.3-14.5]; P = .04), and baseline troponin-T level (median [IQR], 0.013 [0.009-0.022] vs 0.011 [0.007-0.015] ng/mL [to convert to micrograms per liter, multiply by 1]; P = .04) and greater overnight troponin-T level increases (change in median [IQR], 0.0021 [−0.0029 to 0.0062] vs 0.0002 [−0.0022 to 0.0026] ng/mL; P = .02). New York Heart Association class II or III symptoms were more common in those with SDB (48 [52.7%] vs 17 [27.0%]; P = .005). Hypertension and diabetes were more prevalent among patients with SDB than without SDB (hypertension: 67 [73.6%] vs 36 [57.1%]; P = .03; diabetes: 14 [15.4%] vs 3 [4.8%]; P = .04), whereas rates of atrial fibrillation and prior myectomy did not differ significantly between groups. Conclusions and Relevance This study suggests that undiagnosed SDB is highly prevalent in patients with HCM and that SDB is associated with adverse myocardial remodeling, greater diastolic dysfunction, and elevated troponin-T levels, indicating subclinical myocardial injury. SDB may contribute to HCM pathophysiology and symptom burden, supporting the rationale for randomized clinical trials to determine the impact of treating SDB on symptoms and clinical outcomes in patients with HCM.

Background: Sleep disordered breathing (SDB) is frequently observed in patients with cardiovascular disease, and is associated with intermittent hypoxia, sympathetic activation, oxidative stress, and endothelial dysfunction, all of which may facilitate the development and progression of cardiovascular disease. Objectives: We sought to determine the prevalence, subtypes, and clinical implications of comorbid SDB in patients with hypertrophic cardiomyopathy (HCM). Methods: In this prospective observational study, patients with HCM without prior diagnosis of SDB were recruited to undergo inpatient polysomnography between May 1 st 2018 and October 31 st 2022. Electrocardiographic and echocardiographic parameters, cardiac biomarkers, and symptoms were comparatively assessed in patients with and without comorbid SDB. Patients were assessed for the development of major adverse cardiovascular events (MACE) during follow-up (median 29, range 3-57 months). Results Among 154 participants, 91 (59.1%) were diagnosed with SDB of whom 38 (41.8%) had mild, 22 (24.2%) moderate, 18 (19.8%) severe obstructive sleep apnea, and 13 (14.3%) had central sleep apnea. SDB was associated with greater left ventricular mass (median [IQR]) (128 [107, 161] vs. 109 [96, 134] g/m 2 , p =0.034) and E/e’ ratio (12.5 [10, 15] vs. 10.0 [8.3, 14.5], p =0.039). Patients with HCM over the age of 50 years, with body mass index ≥ 30kg/m 2 , who described their sleep as “poor” were at particularly high risk of having comorbid SDB, as were those who were diabetic, hypertensive, or described greater exertional limitation (NYHA Class ≥II 53% vs. 27%, p =0.005). Importantly, subjects with SDB had elevated baseline Troponin T levels (14 ng/L vs 11 ng/L, p =0.030), and further substantial overnight troponin increases following untreated apneic sleep (2.1ng/L vs 0.2ng/L, p =0.009). Finally, patients with comorbid SDB experienced a significantly higher proportion of incident adverse cardiovascular events (MACE hazard ratio 5.3, 95% CI, 1.6, 17.2, p =0.006) than those without SDB. Conclusions: We report a particularly high burden of previously undiagnosed SDB in patients with HCM, particularly in older, heavier, male patients. Undiagnosed SDB in HCM is not benign and is associated with symptom progression, comorbidity, and a poorer prognosis, particularly in the case of central sleep apnea. These important new findings provide rationale for heightened vigilance and routine screening for SDB in patients with HCM.