Ischemia and atherosclerotic coronary artery disease in patients with hypertrophic cardiomyopathy: a review of incidence, pathophysiological mechanisms, clinical implications and management strategies.

Ischemia is suspected to occur frequently in patients with HCM and may result from various mechanisms, for example decreased coronary flow reserve, disease of small intramuscular arteries, "inadequate' size of coronary arteries relative to hypertrophied myocardium, diminution of coronary flow during systole, compression of septal perforator arteries during systole, coronary artery spasm, and co-existent atherosclerotic CAD, which can be present in up to a quarter of HCM patients above 45 years of age. The diagnosis of CAD in patients with HCM is difficult to make on clinical grounds, secondary to the high frequency of angina in patients with HCM without CAD. Pharmacological stress echocardiography is promising but needs to be further studied; stress thallium imaging is beset with frequent false positive results. At this time, coronary angiography remains the only reliable test for the definitive diagnosis of co-existent CAD in HCM. Beta-blockers and verapamil may help in relieving symptoms and silent ischemia in patients with HCM; in those with coexistent CAD and resistant symptoms, CABG alone or in combination with left ventricular myectomy or mitral valve replacement has been recommended.