A 45-year-old male with a history of well-controlled essential hypertension and hyperlipidemia was evaluated for dyspnea on exertion and murmur. The physical exam was remarkable for grade 3/6 systolic murmur that increased with valsalva. His EKG is shown in Figure 1. He was diagnosed with hypertrophic obstructive cardiomyopathy, with a resting left ventricular outflow tract (LVOT) gradient of 100 mm Hg and basal septal thickness of 20mm. He was treated with maximal tolerated verapamil with significant improvement in his symptoms and resolution of resting and provocative LVOT gradient.
Over the subsequent five years, he led a sedentary life style and gained approximately 70 lbs. He noticed some dyspnea on exertion. Physical examination revealed Height 6 feet 4 inches, Weight 151.2 kilograms, Blood pressure 122/70, heart rate 89 beats/min, room air pulse oximetry was 96%.
There was a grade 2-3 systolic murmur in the sitting position, but with provocation (Valsalva maneuver and brisk stand) this increased to a grade 4/6. Echocardiogram revealed Hypertrophic obstructive cardiomyopathy, basal septal variant (thickness of 28 mm Hg) with a resting LVOT gradient of 50 mmHg increasing to 70 mmHg with Valsalva maneuver and ejection fraction of 75%. Metoprolol succinate was added and titrated up to maximal tolerated doses. He also underwent an overnight pulse oximetry, which showed desaturations down to as low as 75%, and saturations of < 89% for 1.5 hours. A polysomnogram was performed revealing OSA with an apnea-hypopnea index of 11/hour. He was started on continuous positive airway pressure mask, which he was complaint to. Weight loss counseling was done. On one-year follow-up, he had significant improvement in his symptoms and improvement in the resting and provocative LVOT gradients.
Figure 1
Which of the following is false regarding sleep apnea in patients with hypertrophic cardiomyopathy?
Show Answer
The correct answer is: 5) In patients with OSA, left ventricular hypertrophy develops only in the setting of elevated blood pressure.
Description:
Obstructive sleep apnea (OSA) is the most common type of sleep-disordered breathing and is recognized as a major public health problem, with an extremely high prevalence among patients with established metabolic and cardiovascular disease. For instance, the estimated prevalence of OSA among patients with hypertension,1,2 resistant hypertension,3 AF,4 and metabolic syndrome 5 ranges from 30% to 90%. This high prevalence of OSA among patients with established cardiovascular disease is in part explained by the fact that both share several common risk factors, such as increasing age, obesity, sedentary life, and male sex.
Hypertrophic cardiomyopathy (HCM) is a genetic disease, some of these patients are diagnosed at young ages and do not necessarily possess the typical traits of patients with established metabolic and cardiovascular disease. However, despite that, the patients with HCM consistently have a high prevalence of OSA, ranging from 32% to 71%.6-9 There is also evidence that the presence of OSA is independently associated with worse structural and functional impairment of the heart, including over dilation of the left atrium and aorta, higher prevalence of atrial fibrillation (AF), worse New York Heart Association (NYHA) functional class, as well as quality of life 7-10. In a study looking at association of OSA with AF in HCM,7 patients with OSA had signs of heart remodeling characterized by increased left atrial diameter. Left atrial diameter and OSA severity were the only factors independently associated with AF in multivariate analysis in this study. AF, a marker of cardiac mortality in patients with HCM, was fivefold more common in patients with, than without, OSA. 7
Patients with OSA have elevated catecholamine levels that could influence the pathophysiology of HCM by increasing hypertrophy and left ventricular filling pressures, decreasing cardiac output and initiating or worsening LVOT obstruction, dyspnea and dizziness, and mitral regurgitation. Hypertrophy of the septum has previously been shown to be independently associated with OSA severity, and to reverse after initiation of CPAP therapy.11 In patients with OSA, left ventricular hypertrophy develops even in the setting of normal blood pressure, which suggests that factors other than hemodynamic overload contribute to hypertrophy.11 Effective treatment of sleep apnea can improve symptoms and obviate the need for septal reduction in the medium term. Given these potential adverse effects of nocturnal hypoxemia-induced sympathetic activation on HCM symptoms and outcomes coupled with the high prevalence of abnormal oximetry in this population, screening and appropriate management for OSA in patients with HCM is recommended. Further studies are needed to determine the long-term benefit of OSA treatment on hemodynamics and disease progression in HCM.
References
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Eleid MF, Konecny T, Orban M, Sengupta PP, Somers VK, Parish JM, et al. High prevalence of abnormal nocturnal oximetry in patients with hypertrophic cardiomyopathy. J Am Coll Cardiol 2009; 54:1805–1809.
Pedrosa RP, Drager LF, Genta PR, Amaro AC, Antunes MO, Matsumoto AY, et al. Obstructive sleep apnea is common and independently associated with atrial fibrillation in patients with hypertrophic cardiomyopathy. Chest 2010;137:1078–1084.
Konecny T, Brady PA, Orban M, Lin G, Pressman GS, Lehar F, et al. Interactions between sleep disordered breathing and atrial fibrillation in patients with hypertrophic cardiomyopathy. Am J Cardiol 2010;105:1597–1602.
Prinz C, Bitter T, Oldenburg O, Horstkotte D, Faber L. Incidence of obstructive sleep apnea in patients with hypertrophic cardiomyopathy. Congest Heart Fail 2011;17:19–24.
Pedrosa RP, Lima SG, Drager LF, Genta PR, Amaro AC, Antunes MO, et al. Sleep quality and quality of life in patients with hypertrophic cardiomyopathy. Cardiology 2010;117:200–206.
Sengupta PP, Sorajja D, Eleid MF, et al. Hypertrophic obstructive cardiomyopathy and sleep-disordered breathing: an unfavorable combination. Nat Clin Pract Cardiovasc Med 2009;6:14–15.
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