Apical Hypertrophic Cardiomyopathy.

Abstract

To the Editor We have read with interest the excellent review on hypertrophic cardiomyopathy (HCM)1 and wish to comment on the apical variant of the disease listed in Table 4 but not discussed in the text. This variant can be found in 15% to 25% of Chinese and Japanese cohorts with HCM but only in 3% of American cohorts.2 The typical electrocardiography (ECG) shows the loss of septal Q waves, high QRS voltage, and repolarization abnormalities with deep T-wave inversion, especially in the leads closest to the apex—V4–V6.2 Because hypertrophy is confined to the apex, dynamic left ventricular outflow tract obstruction and systolic anterior motion of the anterior mitral valve leaflet are absent. The apical pulse may be sustained on palpation, and an S4 heart sound may be heard.2 There may not be a systolic murmur. It is reasonable to expect some degree of diastolic dysfunction and the possibility of relative apical ischemia as a result of the unbalanced wall thickness-to-vascular supply ratio.3 HCM apical variant may not have a totally benign prognosis with atrial fibrillation and myocardial infarction occurring in up to one-third of patients during long-term follow-up in the Western population.3,4 In addition, in patients with atrial fibrillation, HCM (including the apical variant) may increase the risks of systemic thromboembolism and the need for long-term anticoagulation.5,6 However, there are currently no data to suggest that the perioperative risks are increased in afflicted patients without a history of syncope, chest pain, dyspnea, or heart failure. Nonetheless, in a young asymptomatic patient, the bizarre ECG pattern first seen when intraoperative ECG electrodes are placed can be alarming and may even lead to the postponement of surgery or initiation of coronary vasodilator treatment. Alternatively, a preoperative ECG may lead one to suspect HCM. However, plain echocardiography may still miss apical HCM if the apex is not adequately examined.3 A microbubble contrast-enhanced echocardiography or cardiac magnetic resonance imaging, or both, may be required to differentially diagnose apical HCM, coronary artery disease, myocardial tumor, ventricular aneurysm, ventricular noncompaction, or endomyocardial fibrosis.3 Anthony M. H. Ho, MD, FRCPC, FCCP Department of Anesthesiology and Perioperative Medicine Queen’s University and Kingston General Hospital Kingston, Ontario, Canada [email protected] Po T. Chui, MBBS, FANZCA Alex P. W. Lee, MBChB, MRCP Song Wan, PhD, MD, FRCS Departments of Anaesthesia and Intensive Care, Medicine & Therapeutics, and Surgery The Chinese University of Hong Kong and Prince of Wales Hospital Hong Kong SAR, People’s Republic of China