Choose the true statement regarding patients with hypertrophic cardiomyopathy (HCM):
A vigorous exercise regimen is recommended for these patients as strict conditioning improves myocardial oxygen supply and demand ratios and thus cardiac performance.
+Bedside diagnostic interventions that increase left ventricular filling (such as the Valsalva maneuver or standing) or decrease myocardial contractility (such as intravenous isoproterenol) will accentuate the systolic ejection murmur.
+The mainstay of medical therapy for HCM is ACE inhibitors.
+The onset of paroxysmal or sustained atrial arrhythmias often results in a deterioration of functional status.
+Since there is no valvular pathology involved, prophylactic antibiotics are not needed prior to invasive procedures.
HCM, an autosomal dominant disorder, is characterized by asymmetric septal hypertrophy and myocardial fiber disarray. Dyspnea on exertion is the most frequent presenting complaint, but palpitations, chest pain, and postexertional syncope are other manifestations. Symptoms worsen with age. Atrial and ventricular tachyarrhythmias are common. The systolic ejection murmur of HCM is decreased by actions that increase LV filling, such as isometric handgrip and squatting. EKG findings in “pure” HCM include left ventricular hypertrophy and left atrial enlargement and a “pseudoinfarction” pattern of Q waves without T-wave inversion. Sudden cardiac death occurs in 4% of patients per year and not uncommonly follows vigorous exercise. The severity of symptoms does not correlate with the risk of death. In symptomatic patients who fail to respond to beta-blockers, calcium channel blockers are used. Surgical therapy has not been conclusively shown to be beneficial. These patients should receive antibiotic prophylaxis for endocarditis.