Apical hypertrophic cardiomyopathy

ECG: Sinus rhythm; left ventricular hypertrophy with major increase in R wave voltages from V2 to V6; incomplete right bundle branch block pattern (QRS duration 118 ms); absence of q waves in left precordial leads; negative T waves in leads I, aVL, V1-V6; giant negative T waves (> 10 mm) in V2-V3; ultrasound and MRI revealed a characteristic pattern of apical hypertrophic cardiomyopathy;

ECG 2: 34-year-old man with apical hypertrophic cardiomyopathy;

ECG 2: Sinus rhythm; left ventricular hypertrophy with major increase in R wave voltages in V4-V5 and S wave voltages in V1-V2 (highly positive Sokolow index); absence of q waves in left precordial leads and in leads I, aVL; giant negative T waves (> 10 mm) in V4-V5;

ECG 3: 18-year-old brother seen in consultation to determine if he is also afflicted with heart disease;

ECG 3: Electrical pattern similar to that of his brother, very suggestive of apical hypertrophic cardiomyopathy (left ventricular hypertrophy, absence of septal waves, giant negative T waves);

Comments: Apical hypertrophic cardiomyopathy, initially described by Sakamoto in 1976 in Japanese patients, is a rare form of hypertrophic cardiomyopathy predominantly observed in Asian patients (15 to 25% of hypertrophic cardiomyopathies in Japan versus 1 to 5% in the West). Hypertrophy is predominantly localized at the apex of the left ventricle and generally does not involve dynamic obstruction at ejection. It is a disease most often inherited although it can be observed in some patients without family history. While diagnosis can be confirmed by ultrasound, MRI or left ventricular angiography (diastolic ace of spades configuration), the electrocardiogram can be very evocative with the presence of giant T waves (greater than 10 mm) in precordial leads in conjunction with large R waves and constitutes a determining element of the diagnostic tree, especially in asymptomatic patients.

The characteristic electrocardiographic pattern includes:

• Disappearance of the septal wave in the left precordial leads which may be related to the presence of intraventricular conduction disorders;
• R-waves sometimes of very large amplitude; with the hypertrophy predominating at the apex, there is no electrical opposition of the zones that face the apex (non-muscular elements of the fibrous skeleton constituting the mitral valves and the mitral annulus), which explains the sometimes severe amplitude of the R waves;
• Giant inverted T waves possibly related to an inversion of the repolarization sequence between the septum and apex; the amplitude of the negative T waves exceeds 10 mm in about 50% of patients; these negative T waves are preferentially observed in the lateral, inferior and mid precordial leads;

Although the prognosis of patients with this hypertrophic cardiomyopathy appears to be preserved, certain studies have found an increased incidence of sudden death due to ventricular arrhythmia, with the hypertrophied muscle constituting a substrate conducive to the occurrence of monomorphic or polymorphic tachycardias.

A negative T wave may be physiological in leads aVR, III or V1. Negative T waves can also be observed in many clinical situations: ischemia, pericarditis, metabolic disorder, major anxiety, cocaine intake, hyperventilation syndrome, digoxin treatment, etc. The giant negative waves (> 5-10 mm) pattern observed in this type of heart disease is relatively characteristic although there are a number of differential diagnoses: increased intracranial pressure, stroke and particularly subarachnoid hemorrhage (giant T waves and prolonged QT interval), myocardial ischemia (negative deep T waves from V1 to V4 in Wellens syndrome), post-tachycardia and post-pacing Chatterjee effect.

Take-home message: The presence on the electrocardiogram of signs of left ventricular hypertrophy and giant negative T waves with the disappearance of septal q waves should evoke the diagnosis of apical hypertrophic cardiomyopathy. Performing an MRI enables eliminating differential diagnoses.