Apical Hypertrophic Cardiomyopathy

A 75-year-old white man without cardiac symptoms was referred to our cardiology clinic with a long history of abnormal electrocardiographic findings. Cardiac risk factors included hyperlipidemia and a family history of heart disease. Upon physical examination, his heart rate was 49 beats/min and his blood pressure was 106/70 mmHg. No extra heart sounds or murmurs were heard, even after provocative maneuvers. His electrocardiogram showed sinus bradycardia, left ventricular (LV) hypertrophy, and negative T waves in derivations from the precordium and the extremities (Fig. 1). Results of his Holter monitor studies were normal. Echocardiography revealed a preserved LV systolic function (ejection fraction, 0.55) with normal LV wall motion and thickness.

Fig. 1 A 12-lead electrocardiogram shows sinus bradycardia, left ventricular hypertrophy with effort, and T-wave inversions.

To investigate the cause of the abnormalities on the electrocardiogram, we performed cardiac magnetic resonance imaging (MRI). We obtained cardiac-gated, multiplanar cine images, which demonstrated a marked concentric thickening of the LV apex that gradually decreased to normal levels at the base (Fig. 2). There was no regional LV wall-motion abnormality (Fig. 2A).

Fig. 2 Cardiac-gated, breath-hold, gradient-echo magnetic resonance images of the heart in A) 4-chamber and B) left ventricular outflow tract views show a marked hypertrophy of the left ventricle, which is more pronounced in the apex (arrowheads).

Real-time motion image of Fig. 2A is available at texasheart.org/journal.

Comment

Apical hypertrophic cardiomyopathy (HCM) is characterized by hypertrophy of the myocardium, predominantly in the left ventricular apex.^1–5 This relatively rare variant of HCM, first described in Japan, constituted 13% to 25% of all cases of HCM in Japan^1,2; however, it is seen much less often in non-Japanese populations.⁵ Despite a relatively good prognosis for apical HCM, long-term observations have occasionally included sudden cardiac death, severe arrhythmias, and apical infarctions with apical aneurysms.⁵ A “spade-shaped” configuration of the LV cavity at end-diastole on ventriculography and “giant” T-wave negativity in the electrocardiogram have been reported as the typical findings for this abnormality.^1,2

Echocardiography has been the 1st-line imaging method for patients with suspected HCM, but its shortcomings in evaluating the apex are well known.⁴ A cardiac MRI should be performed if the electrocardiogram raises suspicion of apical HCM and if echocardiographic results are inconclusive or technically inadequate.³

Some echocardiographers will miss the diagnosis of apical thickening if the apex is not clearly seen, or if a thickened apex is mistaken for apical foreshortening on planar imaging.⁴ Cardiac MRI avoids this problem because it is less dependent on operators, is not subject to acoustic-window limitations, has multiplanar capability, and displays excellent soft-tissue contrast.^3–5