Apical hypertrophic cardiomyopathy presenting as acute coronary syndrome

Case report

A 70-year-old man was referred to our emergency room with severe chest pain two hours after the onset of symptoms. His chest pain was induced by physical activity, but persisted at rest. Similar symptoms had not occurred prior to the current event, nor had dyspnea or syncope. His medical history included cardiovascular risk factors such as arterial hypertension, hyperlipidemia and a family history of coronary artery disease. There was no family history of sudden cardiac death. His cardiac enzymes were not elevated. The electrocardiogram showed giant negative T wave inversion in the lateral precordial leads (V3–V6) (Figure 1). As a result of the typical symptoms of unstable angina pectoris, electrocardiographic repolarization disturbances indicative for acute myocardial ischemia and his cardiovascular risk profile, the decision was made to carry out cardiac catheterization. Coronary angiography excluded significant coronary artery disease. However, left ventriculography demonstrated a typical spade-like configuration of the left ventricular (LV) cavity (Figure 2). Transthoracic echocardiography revealed no pathological finding, but the LV apex could not be adequately visualized. The intra-cavitary gradients were not measured. Cardiac magnetic resonance (CMR) imaging was therefore performed for further differential diagnosis. A localized apical hypertrophy with a spade-like configuration of the LV cavity at end-diastole and an obliteration of the distal LV cavity at end-systole were observed (Figure 3(a) and 3(b)). The wall thickness of the basal regions and systolic LV function were normal. A local late gadolinium enhancement in the hypertrophic apical region was detected (Figure 4(a) and 4(b)).

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Figure 1.

Electrocardiography at admission with T wave inversion >10 mm.

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Figure 2.

Left ventriculography demonstrating the typical spade-shaped configuration of the LV cavity.

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Figure 3.

Cine cardiac magnetic resonance at (a) end-diastole and (b) end-systole demonstrating (apical hypertrophy and spade-like morphology at end-diastole and a complete disappearance of apical cavity at end-systole).

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Figure 4.

Late gadolinium enhancement cardiac magnetic resonance at (a) four-chamber long axis and (b) two-chamber view demonstrating transmural necrosis of the apical myocardium (red arrows).

The patient was diagnosed with apical hypertrophic cardiomyopathy (AHCM) and a drug regimen consisting of a β-blocker and a calcium antagonist was initiated. Based on the estimated hypertrophic cardiomyopathy risk–sudden cardiac death score, no internal cardiac defibrillator was implanted.

This case history underlines the role of CMR in the diagnosis of AHCM. The prevalence of AHCM differs between ethnic groups; in the Japanese population it accounts for up to 25% of cases of hypertrophic cardiomyopathy, whereas it does not exceed 2% in the Western population. Many patients with AHCM are asymptomatic, while others present with chest pain, palpitations, dyspnea or syncope. Although severe clinical manifestations, including sudden cardiac death, malignant arrhythmias and apical infarction with apical aneurysm, have been described, cardiovascular mortality is lower than in other variants of hypertrophic cardiomyopathy. ¹

The typical electrocardiographic findings are the presence of giant T wave negativity defined as a voltage of negative T wave ⩾1 mV and a high R wave voltage. The characteristic finding in transthoracic echocardiography is a localized apical hypertrophy causing a spade-like configuration of the LV cavity. However, echocardiographic assessment of apical LV function and morphology can only be performed adequately in approximately half of all patients. CMR is a useful adjunctive imaging modality as a result of its good visualization of all segments, including the apex. In addition, CMR can objectify myocardial fibrosis related to cardiovascular mortality. A ratio between the apical and basal LV wall thicknesses ⩾1.3–1.5 or an apical wall thickness >15 mm are characteristically present and are thus important diagnostic criteria of AHCM. ²

With the aim of improving symptoms, a medical therapy consisting of ß-blockers and calcium antagonists should be initiated in symptomatic patients with AHCM. ³ An implantable cardioverter defibrillator should be considered based on the estimated hypertrophic cardiomyopathy risk–sudden cardiac death score.

In conclusion, AHCM can mimic the symptoms and electrocardiographic changes of acute coronary syndromes and should therefore be considered as a differential diagnosis, especially in patients with giant T wave negativity and spade-like configuration of the LV cavity. As a result of the often poor echocardiographic visualization of the apical segments, CMR is helpful in establishing the diagnosis of AHCM. The additional assessment of apical fibrosis by CMR may help in risk stratification and the management of patients with AHCM.