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Stress-induced Cardiomyopathy, also called transient left ventricular apical ballooning or ampulla cardiomyopathy, is a clinical entity first described by Dote et al in the Japanese population in 1990s 1, particularly in women of post-menopausal age. They coined the term ‘Tako-Tsubo left ventricular dysfunction’ after the distinctive shape of the end-systolic left ventriculogram which was reminiscent of a ‘tako-tsubo’, an octopus trap used in Japan. This syndrome is characterised by a peculiar, yet characteristic, transient regional systolic dysfunction concerning the left ventricular apex and mid-ventricle, with hyperkinesis of the basal left ventricular segments. Despite the ventricular dysfunction, there is absence of obstructive atherosclerotic coronary disease.
There is much conjecture but little evidence to explain the aetiology of the syndrome, with several possible mechanisms implicated. These include multivessel epicardial spasm, microvascular coronary dysfunction, catecholamine-induced injury and neurohumoral-related myocardial stunning 2. Emotional stress including sudden accidents, natural disasters, death or the funeral of a family member, in addition to other triggering factors such as cerebrovascular accidents, epileptic attacks and non-cardiac surgery, might play a key role in the development of this cardiomyopathy, but the precise aetiological mechanisms remain unidentified 3.
A 73 year-old lady attended the emergency department following the sudden onset of acute dyspnoea. Her breathlessness had presented following a short walk from a bus stop to her house in darkness at 0130h, when she was “very frightened”. Her past medical history included hypertension, hypercholesterolaemia, non-insulin dependent diabetes mellitus and she was an ex-smoker. Notably, Bisoprolol 5mg daily was among her prescribed medications. Electrocardiogram (ECG) on presentation demonstrated left bundle branch block and first-degree atrioventricular block, both of which were longstanding. Subsequent peak Troponin-T was elevated at 0.65 ug/L (NR < 0.03 ug/L).
Examination revealed a pulse rate of 82/min, blood pressure 106/62 mmHg, an elevated venous pressure, apical pan-systolic murmur (2/6) and fine end-inspiratory bibasal crepitations. Routine laboratory investigations were within normal ranges.
Echocardiography demonstrated a non-dilated left ventricle, which had moderately impaired systolic function. There was extensive apical akinesis extending to the mid-segments of septal, lateral, inferior and anterior walls in addition to mild functional mitral regurgitation. Coronary Artery Angiogram revealed non-obstructive coronary disease (Fig.1). Left Ventriculogram depicted characteristic apical ballooning (Fig.2--3),3), corresponding to the anteroapical and inferoapical akinesis seen on echocardiography. Subsequent Pro-B-type Natriuretic Peptide (NT-ProBNP) was significantly elevated at 16922 ng/L (NR < 349 ng/L). Our patient was treated with intravenous diuretics as standard, and was discharged one week later euvolaemic and with an improving NT-ProBNP (4734 ng/L). Follow-up echocardiography one-month post-discharge, showed complete resolution of the extensive apical akinesis and normalisation of the NT-ProBNP to 290ng/L, confirming the diagnosis as that of Takotsubo Cardiomyopathy.
Takotsubo Cardiomyopathy affects predominately postmenopausal women who, in times of heightened emotional or physical stress, typically present with chest pain, pulmonary oedema, and cardiogenic shock 1,5. In the initial stages, ECG changes include a prolonged PR and QT intervals, ST elevation in the precordial leads mimicking acute anterior myocardial infarction, T wave inversion and pathological Q waves. In the 48-hours following symptom onset, most patients develop a prolonged QT interval that subsequently resolves 4. The presentation mimics an acute coronary syndrome with chest discomfort and ECG changes signifying myocardial ischaemia, however the enzyme release is disproportionately low in relation to both ECG changes and regional wall-motion abnormality 5-7. Differential diagnoses to be considered in reversible LV dysfunction include tachycardia-induced cardiomyopathy, myocarditis and nutritional deficiency (Table 1). Treatment of Takotsubo cardiomyopathy remains largely pragmatic, with standard supportive care for congestive heart failure including diuretics and vasodilators 8.
The reported known complications with this disorder, in addition to recurrence of the syndrome, are those of left ventricular failure, cardiogenic shock, arrhythmias, mitral regurgitation, LV free-wall rupture, and rarely death 9.
The closest approximation to diagnostic criteria are those used by Tsuchihashi 5, who published the findings of 88 patients with transient apical ballooning, who were enrolled in a multicentre registry of acute MI. Tsuchihashi selected the following criteria for the identification of Takotsubo Cardiomyopathy:
Baybee et al have proposed the Mayo Clinic Diagnostic criteria 9 (Table 2). These criteria, like those of Tsushihashi, demand reversible dysfunction of the apex and midventricle. Much speculation surrounds the mechanism of stress cardiomyopathy. Likely mechanisms can be divided into three broad categories: coronary vasospasm; ventricular outflow tract obstruction with apical systolic dysfunction; and catecholamine injury. LV outflow tract obstruction by basal septal hypertrophy can be easily excluded by echocardiography. Catecholamines have been identified as playing a central role in the pathogenesis of Takotsubo cardiomyopathy 4. They are well recognised as having a toxic effect on the myocardium, e.g. responsibility for the reversible ventricular dysfunction seen in phaeochromocytoma 10. Elevated catecholamine levels decrease the viability of myocytes through cyclic adenosine monophosphate (cAMP)–mediated calcium overload and are also a potential source of oxygen-derived free-radicals that may cause myocyte injury. Free-radicals can interfere with sodium and calcium transporters, possibly resulting in myocyte dysfunction through increased trans-sacrolemmal calcium influx and cellular calcium overload 11. In summary, the mechanism of catecholamine-induced cardiotoxicity is multifactorial and involves unrelenting activation of calcium channels, membrane damage and microvascular spasm 12. Of particular note, background fixed wall motion abnormalities, as in this case, only contribute to the apical akinesis and provide no proven aetiological stimulus 13.
Patients with Takotsubo cardiomyopathy have been shown to possess higher catecholamine levels than patients with acute myocardial infarction in the same Killip class 4. Since the apical myocardium is particularly receptive to sympathetic stimulation this may explain the characteristic pattern of changes seen on echocardiography and angiography 13.