|Apical Hypertrophic Cardiomyopathy|
Apical Hypertrophic Cardiomyopathy
Ravi Dave, M.D.
A 59-year-old male of Japanese descent presented with worsening chest pain. His history was pertinent for hypertension and coronary artery disease. In the past he had undergone coronary angioplasty of a diagonal branch of the left anterior descending artery. He presented on this occasion with progressive exertional chest pressure and had deep symmetric T wave inversions on his precordial leads. After reviewing his ECG and his symptoms, the patient was recommended to undergo an urgent coronary angiogram to evaluate for unstable coronary artery disease. Coronary angiography revealed evidence of non-obstructive coronary artery disease. The left ventricle was hyperdynamic with systolic cavity obliteration of the distal third and apical portions of the left ventricle. Simultaneous hemodynamic measurements done in the apical area and the base of the left ventricle revealed a pressure gradient of 110 mmHg. A diagnosis of apical (Japanese) variety of hypertrophic cardiomyopathy was made, and the patient was treated with beta blockers. The patient's symptoms improved on medical therapy.
A 79-year-old male of Korean descent presented to the emergency room with progressive chest pains suggestive of unstable angina. His coronary risk factors included a history of hypertension, type-2 diabetes mellitus, hyperlipedemia, premature atherosclerosis in family members and known peripheral vascular disease. His ECG on admission revealed deep symmetric T wave inversions in anterior precordial leads. A coronary angiogram was recommended. At the time of angiography, he was found to have evidence of non-obstructive coronary artery disease with systolic obliteration of distal portion of his left ventricle. Simultaneous pressure measurements detected a difference/gradient of 60 mmHg between the apex and base of the left ventricle. The patient was treated with beta blockers for a diagnosis of apical hypertrophic cardiomyopathy. In follow-up the patient developed symptoms of dizziness and near-syncope. A Holter monitor discovered brief runs of monomorphic, non-sustained ventricular tachycardia.
An electrophysiology evaluation was done due to his high risk for ventricular arrhythmia. Sustained ventricular tachycardia was induced, and the patient was treated with an implantable cardioverter defibrillator device. The patient continues to do well on medical therapy.
Hypertrophic cardiomyopathy (HCM) is characterized by an increased myocardial mass with a resultant small ventricular cavity. The left ventricle is more involved than the right and the patterns of hypertrophy are myriad. A classic feature is asymmetric hypertrophy of the interventricular septum compared to the other areas. More recently, genetic transmission and mutations have been identified and felt to contribute to its etiology.
Apical HCM is a variant with predominant involvement of the apex of the heart. This condition was first described in Japanese males in 1976.1 This condition is common in Japan and estimated to represent 25% of Japanese patients with HCM. Lately, many cases have been reported in patients other than those of Japanese origin.
Patients can present with symptoms of angina and dyspnea with a predominant exertional component. Apical HCM patients tend to have milder symptoms. Palpitations and syncope should prompt further evaluation of arrythmias. Atrial arrhythmias (from atrial dilation) and serious ventricular arrythmias have been described in patients with apical HCM. Patients with ventricular arrythmias are at high risk for sudden death and should have further electrophysiological evaluation.
Physical examination in patients with apical HCM may be non-contributory with only the presence of a left ventricular lift and a loud fourth heart sound. Patients with an obstructive left ventricular outflow tract have the classic signs described in literature.
Electrocardiography shows evidence of giant inverted T waves in the mid precordial leads. Other abnormalities could include evidence of left atrial enlargement/abnormality, abnormal axis deviation and evidence of premature ventricular and atrial contractions. Presence of Q waves generally suggests depolarization of myopathic cells in the myocardium with abnormal electrophysiologic properties. Chest roentgenography may show evidence of cardiomegaly with left atrial enlargement.
Echocardiography has been commonly used for detection and screening of all types of HCM.
Evaluation of wall thickness from hypertrophy, chamber sizes, associated valvular diseases, diastolic dysfunction and estimation of degree of left ventricular outflow obstruction can be done by this method. In these patients, diastolic dysfunction is consistently abnormal with slow early ventricular filling associated with increased dependence on atrial contraction and late diastolic filling.
In patients with apical HCM, a transthoracic echocardiogram may be inadequate, and the hypertrophy localized to the apex may be missed. In these patients, techniques such as transesophageal echocardiography have been utilized to better visualize the apex. In some cases apical hypertrophy may be confused with apical thrombus. Differentiation between these conditions can be done by utilizing a novel technique called myocardial contrast echocardiography. In this technique, a contrast agent is injected intravenously to highlight hypertrophied myocardium by echocardiography.
Other noninvasive modalities like stress perfusion scintigraphy may suggest an enhanced tracer uptake in the apical area of the left ventricle. Nuclear magnetic resonance imaging reveals the pathognomonic "ace of spades" configuration of the left ventricle with systolic obliteration of the apical region.
Cardiac catheterization is frequently done in these patients due to similarity in symptoms and ECG findings with acute coronary syndromes. Ventriculography shows the classic sign of systolic obliteration of the apex and a small ventricular cavity at the base. A pressure gradient demonstrated between the left ventricular apex and the base as detected in our patients could represent true obstruction at that level versus false elevations in pressure measurements by catheter entrapment. Concomitant coronary artery disease can be found in patients with risk factors for atherosclerosis. In addition, the left anterior descending coronary artery and its septal branches may demonstrate phasic narrowing during systole (myocardial bridging) in the absence of underlying obstructive lesions.
In one of the largest reported series, 26 patients were observed for a mean follow-up period of 7.3 years.2 All patients had evidence of diastolic dysfunction and had evidence of apical hypertrophy on echocardiography. The degree of amplitude of negative T waves varied between 2-25 mm. Patients were noted to have a favorable prognosis, with occurrence of an apical myocardial infarction with normal coronary arteries in a single patient. This patient had evidence life threatening ventricular arrythmias. The incidence of significant coronary artery stenosis (>50% in diameter) was low.
In general, patients with apical HCM have a benign course. Symptoms of angina and exertional dyspnea are well controlled with medical therapy with agents like beta blockers and calcium channel blockers. However, regression of hypertrophy is more resistant to treatment with medical agents. Occasionally, these patients develop complications of arrhythmia and require treatment with antiarrythmics or ICD's. Differentiation of this condition from unstable angina and apical thrombus/other masses can be done by use of further imaging modalities.