Abstract 13038: Sleep Disordered Breathing is Associated with Higher Heart Rates in Patients with Hypertrophic Cardiomyopathy Despite Rate Control Therapy
Background: Current guidelines recommend the use of rate control medications for hypertrophic cardiomyopathy (HCM) patients with symptoms of dyspnea and decreased exercise tolerance, based on the rationale that lowering heart rates (HR) of HCM patients may improve these symptoms. Sleep disordered breathing (SDB) is known to increase sympathetic drive and HR in non-HCM patients. Whether the HR of HCM patients with and without SDB differs is not known.
Methods: We prospectively performed overnight oximetry and 24 hour Holter monitoring on consecutive echocardiographically confirmed HCM patients seen at Mayo Clinic, Rochester. SDB was defined by oxygen desaturation index ≥5 (number of ≥4% desaturations per hour of overnight recording). We investigated the relationship between HR (including diurnal variation of HR) and the presence and severity of SDB.
Results: From the 230 HCM patients included in this study (age 54±16 years; 138 male; LVOT pressure gradient at rest 45±39 mmHg), 115 (50%) patients had at least mild SDB (ODI≥5). Presence of SDB was associated with higher mean HR (72 bpm vs. 67 bpm; p=0.002, adjusted p<0.001), even though the use of rate control medications was similar in both groups. The figure below demonstrates that the main difference in HR occurred at night (10pm-5am). Severity of SDB was associated with higher HR (p=0.008), and this was particularly pronounced during the nighttime (p<0.001).
Conclusions: The presence and severity of SDB is associated with higher mean HR despite the use of rate control medications in patients with HCM and could reduce the effectiveness of these agents. Treatment of SDB, which is readily available and has a favorable side effect profile, could improve symptoms by lowering HR in patients with symptomatic HCM.
- © 2011 by American Heart Association, Inc.