Broken heart syndrome: tako-tsubo cardiomyopathy

Discussion

Tako-tsubo or stress cardiomyopathy (also known as apical ballooning syndrome) is a rare, reversible cardiomyopathy. 1 Tako-tsubo is the Japanese word for an “octopus-trapping pot’’ that has a particular shape—a round bottom and narrow neck—resembling the left ventriculogram in systole in this syndrome. 2 Tako-tsubo cardiomyopathy is characterized by transient left ventricular dysfunction, electrocardiographic abnormalities and minimal release of myocardial enzymes in 74%–86% of cases. 3

Its most common clinical presentation includes dyspnea and chest pain mimicking an acute coronary syndrome but without obstructive coronary artery disease. 1^,3 Tako-tsubo cardiomyopathy may be associated with cardiac arrhythmias, including sinus bradycardia, atrioventricular block, atrial fibrillation and ventricular tachycardia or fibrillation. 2

Although tako-tsubo cardiomypathy is a recognized differential diagnosis of acute coronary syndromes, the cardiac troponin I levels in our patient were markedly higher than those previously reported (mean troponin I 0.18 μg/L, interquartile range 0.08–0.69 μg/L; normal < 0.06 μg/L). 4 Atrial fibrillation may occur in 6%–7% of cases; whether this is a precipitant or effect of the catecholamine excess and left ventricular dysfunction is not known. 2

Risk factors

Postmenopausal women appear to be at higher risk of the condition than men. Because of its association with emotional or psychological stressors, such as the death of a loved one, tako-tsubo cardiomypathy has also been called the broken heart syndrome. 4^,5 Other known precipitants include acute intracranial events (bleeding, trauma or ischemic stroke), acute medical illness, surgical procedures, overproduction of endogenous cathecholamines and administration of exogenous cathecholaminergic agents. 5 In about one-third of patients, no preceding emotional or physical stressor is identified. 3

Although the precise pathogenesis is unknown, the following mechanisms have been suggested: enhanced sympathoneural activity, cathecholamine-mediated multivessel epicardial spasm, coronary microvascular dysfunction, and a possible direct cathecholamine-mediated myocyte injury and myocardial stunning. 4^,5

Prognosis

The prognosis is usually good. About one-third of patients recover left ventricular systolic function spontaneously by the time of hospital discharge (1 week). The remainder recover it over the ensuing 1–3 months. The average time to recovery is about 2–3 weeks. 5^,6 The risk of recurrence ranges from 2%–10%, and the long-term prognosis is usually excellent for patients who survive the initial cardiac event. 3^,5

Patients with persistent left ventricular dysfunction at discharge should be prescribed a diuretic and an angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker until left ventricular function returns to normal. 5 In addition, because sympathetic activation is presumed to be pivotal in the pathogenesis, long-term therapy with β-blockers that also have α-adrenergic blocking properties (e.g., carvedilol) should be initiated with the aim of preventing recurrences. 5 However, data are lacking to support these recommendations. Finally, repeat echocardiography should be performed before hospital discharge and after 1–3 months in patients with persistent left ventricular dysfunction.

This case highlights the importance of performing left ventriculography in patients who present with electrocardiographic and cardiac biomarker evidence of acute coronary syndrome but who have normal coronary arteries on angiography.