Approach Considerations
Cardiac markers, specifically troponin I (TnI) and troponin T (TnT), are elevated in 90% of patients with takotsubo (stress) cardiomyopathy (broken heart syndrome), although to a lesser magnitude than is seen in ST-segment elevation myocardial infarction (STEMI). The brain natriuretic peptide (BNP) level is also frequently elevated.
As with any patient in whom acute coronary syndrome (ACS) is suspected, electrocardiography (ECG) should be the initial test obtained soon after presentation to the emergency department (ED).
Transthoracic echocardiography (TTE) provides a quick method of diagnosing wall-motion abnormalities typically seen in takotsubo cardiomyopathy, specifically hypokinesis or akinesis of the midsegment and apical segment of the left ventricle. The diagnosis of takotsubo cardiomyopathy is typically confirmed with cardiac angiography.
Laboratory Studies
In patients with takotsubo (stress) cardiomyopathy (broken heart syndrome), the mean troponin T (TnT) level at the time of admission has been found to be 0.49 ng/mL (normal, < 0.01), and the mean TnI (troponin I) level has been reported as 4.2 ng/mL (normal, < 0.04); during hospitalization, mean peak values for TnT and TnI have been demonstrated to be 0.64 and 8.6 ng/mL, respectively.
As mentioned earlier, the brain natriuretic peptide (BNP) level is also frequently elevated, especially in those patients demonstrating left heart failure; it is an indicator of increased left ventricular (LV) end-diastolic pressures (EDDs) that result from the stunned myocardium.
Takotsubo cardiomyopathy mimics ST-segment elevation myocardial infarction (STEMI). In a study of 66 consecutive patients who were hospitalized with takotsubo cardiomyopathy and 66 patients with STEMI, cardiac biomarkers were determined during 12 hours from admission and compared with demographic, clinical, and echocardiographic findings. [33] Investigators found evidence that the following ratios were capable of distinguishing takotsubo cardiomyopathy from STEMI at an early stage:
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Ratio of N-terminal pro-BNP (NTproBNP) to TnI
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Ratio of NTproBNP to creatine kinase MB (CKMB) mass
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Ratio of NTproBNP to ejection fraction (EF)
Of these, the most accurate marker was the NTproBNP-to-TnI ratio. [33]
Several studies looked at levels of circulating catecholamines in the acute phase and found that nearly 75% of patients had elevations markedly higher than did patients with STEMI. [34, 35]
Echocardiography
As previously stated, Transthoracic echocardiography (TTE) provides a quick method of diagnosing wall-motion abnormalities typically seen in takotsubo (stress) cardiomyopathy (broken heart syndrome), [36] specifically hypokinesis or akinesis of the midsegment and apical segment of the left ventricle (LV). Perhaps most important, these wall-motion abnormalities extend beyond the distribution of any single coronary artery.
The LV ejection fraction (EF) can be estimated by means of echocardiography, cardiac magnetic resonance imaging (MRI), or left ventriculography. Mean LVEF on admission has been found to be in the range of 20%-49%.
Echocardiography is commonly used in following the resolution of the cardiomyopathy and impaired LV function, with LVEF improving to 59%-76% on average, by day 18. (See the images below.)
Cardiac Angiography
The diagnosis of takotsubo (stress) cardiomyopathy (broken heart syndrome) is typically confirmed in the cardiac catheterization laboratory. In a review of 240 patients diagnosed with takotsubo cardiomyopathy, 211 were found to have completely normal coronary arteries, whereas the remainder had noncritical stenoses. The prevalence of normal coronary arteries by angiography in patients presenting with ST-segment elevation myocardial infarction (STEMI) ranges from 1% to 12%. Aside from takotsubo cardiomyopathy, this phenomenon may be explained by transient vessel occlusion with spontaneous thrombolysis, by vasospasm, or by drug effects.
Left ventriculography is perhaps the best imaging modality for demonstrating the pathognomonic wall motion and evaluating left ventricular ejection fraction (LVEF). [26, 27] (See the images below.)
Other Imaging Techniques
Chest radiographs in takotsubo (stress) cardiomyopathy (broken heart syndrome) are often normal, but they may demonstrate pulmonary edema.
Cardiac magnetic resonance imaging (MRI) is increasingly being used as a diagnostic modality that is uniquely suited for establishing the diagnosis of takotsubo cardiomyopathy by accurately visualizing regional wall-motion abnormalities, quantifying ventricular function, and identifying reversible injury to the myocardium by the presence of edema/inflammation and the absence of necrosis/fibrosis. [37, 38, 39, 40]
In addition to evaluating wall-motion abnormalities and left ventricular ejection fraction, cardiac MRI has been found to differentiate takotsubo cardiomyopathy, which is characterized by the absence of delayed gadolinium hyperenhancement, from myocardial infarction and myocarditis, in which the opposite occurs.
Although not indicated in the initial evaluation of patients with takotsubo cardiomyopathy, coronary computed tomography angiography has been used in the subsequent evaluation of patients with the disorder. [41]
Electrocardiography
As with any patient in whom acute coronary syndrome (ACS) is suspected, electrocardiography (ECG) should be the initial test obtained soon after presentation to the emergency department. ST-segment elevation (67-75%) and T-wave inversion (61%) are the most common abnormalities seen on the initial ECG. Ninety-five percent of ST-segment elevations have been found to involve the precordial leads and to be maximal in leads V2 -V3. In comparison with patients with ST-segment elevation myocardial infarction (STEMI) from left anterior descending (LAD) coronary artery occlusion, patients with takotsubo cardiomyopathy had significantly lower amplitude of ST-segment elevations. (See the images below.)
An initially normal or nonspecific ECG finding is seen in 15% of patients with takotsubo cardiomyopathy. Diffuse T-wave inversions tend to occur in the days and weeks following presentation as the ST segments normalize. takotsubo cardiomyopathy cannot be reliably differentiated from STEMI solely on the basis of ECG findings. [26, 30]
In a retrospective study of 33 patients with takotsubo cardiomyopathy, the authors proposed ECG criteria to distinguish takotsubo cardiomyopathy from anterior acute MI in those who presented within 6 hours of symptom onset. The combination of absent abnormal Q waves, absent reciprocal changes, lack of ST-segment elevation in lead V1, and presence of ST-segment elevation in lead aVR had more than 91% sensitivity and 96% specificity for takotsubo cardiomyopathy. [42]
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Electrocardiogram of a patient with takotsubo cardiomyopathy demonstrating ST-segment elevation in the anterior and inferior leads.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Electrocardiogram (ECG) from the same patient discussed in the previous ECG, obtained several days after the initial presentation. This ECG demonstrates resolution of the ST-segment elevation, and now shows diffuse T-wave inversion and poor R-wave progression.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Coronary angiogram of a patient with takotsubo cardiomyopathy demonstrating normal coronary arteries.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Coronary angiogram of a patient with takotsubo cardiomyopathy demonstrating normal coronary arteries.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Ventriculogram during systole in a patient with takotsubo cardiomyopathy demonstrating apical akinesis.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Ventriculogram during diastole in a patient with takotsubo cardiomyopathy.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram of a patient with takotsubo cardiomyopathy during diastole several days after presenting to the emergency department.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram of a patient with takotsubo cardiomyopathy during systole, which demonstrates apical akinesis. The patient's ejection fraction was 40%.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram of the same patient with takotsubo cardiomyopathy during systole discussed in the previous image, nearly 2 months after presenting to the emergency department. Note the improved contractility of the apex. The ejection fraction increased from 40% to 65%.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram of a patient with takotsubo cardiomyopathy during diastole, approximately 2 months after presenting to the emergency department.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram focused on the left ventricle of a patient with takotsubo cardiomyopathy during diastole.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram focusing on the left ventricle of a patient with takotsubo cardiomyopathy during systole. Note the apical akinesis.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram focusing on the left ventricle of a patient with takotsubo cardiomyopathy during systole discussed in the previous image, approximately 2 months after presenting to the emergency department. Note the improved apical contraction.
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Takotsubo (stress) cardiomyopathy (broken heart syndrome). Echocardiogram focusing on the left ventricle of a patient with takotsubo cardiomyopathy during diastole, approximately 2 months after presenting to the emergency department.
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