Sleep Apnea and Hypertrophic Cardiomyopathy

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
Figure 1: Sleep Apnea and Hypertrophic Cardiomyopathy

Which of the following is false regarding sleep apnea in patients with hypertrophic cardiomyopathy?

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