Broken Heart Syndrome ECG: Differentiating Stress Cardiomyopathy from MI

ECG remains an exceptionally useful tool to help differentiate MI from other syndromes which might mimic its symptoms, such as stress cardiomyopathy. Although cases of stress cardiomyopathy, also known as Takotsubo or broken heart syndrome, are thought to be relatively rare—occurring in an estimated 15–30 individuals for every 100,000 people in the United States—its true prevalence in the population is unknown.¹

Millions of Americans currently struggle with economic, social, and emotional stressors, placing them at risk for stress cardiomyopathy. Broken heart syndrome ECG procedures should be used to rule out this condition in any individual who has recently undergone significant stress in their life and presents with suspected symptoms.

Thorough screening can help mitigate potentially serious consequences among patients, as well as the impacts of a prolonged length of hospital stay on an already overutilized and under-resourced healthcare system.

Stress Cardiomyopathy: What to Know

Although the exact causes of stress cardiomyopathy are unknown, extreme life stressors—such as significant emotional, physical, or financial troubles—have long been associated with its development. This acute but reversible syndrome is characterized by transient regional systolic left ventricular dysfunction that resembles acute myocardial infarction.² However, patients with broken heart syndrome do not typically share other coronary artery disease risk factors.²

Most cases of broken heart syndrome occur among postmenopausal women, although anyone can develop the condition.¹ When suspected, broken heart syndrome ECG exams are among first-line diagnostic modalities, along with cardiac biomarkers, coronary angiography, cardiac magnetic resonance (CMR) imaging, and echocardiography.

Accepted diagnostic criteria for this condition include seven components:^{1, 2}

1. Regional and transient wall abnormalities of the left ventricle or right ventricle myocardium that typically appear after a stressful trigger.
2. Wall abnormalities that typically extend beyond a single epicardial vascular distribution.
3. No evidence of atherosclerotic CAD.
4. New ECG changes, such as ST-segment elevation or depression, left bundle branch block, or QTc prolongation—all of which are reversible.
5. Significantly elevated cardiac biomarkers, such as serum natriuretic peptide (BNP or NT-proBNP).
6. Elevated serum cardiac troponin when measured with conventional assay.
7. Recovery of normal cardiac function on cardiac imaging at a follow-up of three to six months.

Since the COVID-19 pandemic, clinicians should also be mindful of the potential impact on heart function, especially since researchers have learned more about ECG abnormalities from studying COVID-19 patients. Other considerations, such as PR-segment depression, may need to be taken into account to differentiate STEMI from myocarditis in this patient population.

What to Look for on ECG

Patients with stress cardiomyopathy and MI tend to report similar symptoms, such as angina. They also typically demonstrate troponin elevations, as one 2016 study in the Journal of the American Heart Association (JAHA) notes. Additionally, there are overlaps in ST abnormalities, as ST elevation (STE) can present in anywhere from 11 to 100% of stress cardiomyopathy cases.³

These similarities historically made it more challenging to differentiate between Takotsubo, STEMI, and NSTEMI, but the large-cohort study in JAHA helped clarify certain ambiguities. By analyzing a retrospective registry of 200 MI and 200 stress cardiomyopathy patients, researchers created a quick-reference flow chart to help guide ACS patient diagnostics using ECG.

The chart in JAHA describes steps clinicians should take when patients present with suspected acute coronary syndrome. First, they should obtain a baseline ECG; the chart then differentiates between features of ST-segment elevation and non-ST segment elevation. By matching elevations and depressions in the ECG to specific leads, clincians can then determine an appropriate diagnosis. The chart provides 95% diagnostic specificity and can help to differentiate between four diagnoses: STE stress cardiomyopathy, non-STE stress cardiomyopathy, STEMI, and NSTEMI.³

All diagnoses involve an assessment of where elevations and depressions occur in the 12 leads. Clinicians should first assess ST segment elevation. If elevation is present, a series of scenarios involving STE and ST segment depression (STD) in different ECG leads can help differentiate STE stress cardiomyopathy from other conditions like STEMI. If there is no ST segment elevation, there are other scenarios that clinicians may use to distinguish non-STE stress cardiomyopathy from NSTEMI.

According to a 2022 study, STE is present in approximately 45% of patients with broken heart syndrome.⁴ Authors note that admission ECGs for stress cardiomyopathy patients with STE were very similar to those with STEMI with the culprit lesion present in the left anterior descending artery. However, those with STE stress cardiomyopathy were less likely to have reciprocal ST segment depression.⁴ The study also shows that STE usually occurs in the earlier phases of stress cardiomyopathy.

Mending Broken Hearts with Faster Detection

Life's many stressors may affect patient health and well-being for months or years to come. Emotional, physical, financial, or other stressors can have a significant impact on cardiac health, even for those with no history of cardiac illness or dysfunction.

Cardiologists should be particularly mindful of patients who may be facing additional stress, such as those enduring serious emotional or financial challenges. Given the overlaps in ACS concerns, diagnostic tools such as ECG that are available at the point of care can help providers accurately detect emergent cardiac issues and avoid incorrect diagnoses.

Resources:

1. Medina de Chazal H, Del Buono MG, Keyser-Marcus L, Ma L, Moeller FG, Berrocal D, Abbate A. Stress Cardiomyopathy Diagnosis and Treatment: JACC State-of-the-Art Review. J Am Coll Cardiol. 2018 Oct 16;72(16):1955-1971. doi: 10.1016/j.jacc.2018.07.072. PMID: 30309474; PMCID: PMC7058348. https://pubmed.ncbi.nlm.nih.gov/30309474/
2. Amin HZ, Amin LZ, Pradipta A. Takotsubo cardiomyopathy: a brief review. Journal of Medicine and Life. 2020;13(1):3-7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175432/
3. Frangieh AH, Obeid S, Ghadri J, et al. Ecg criteria to differentiate between takotsubo (Stress) cardiomyopathy and myocardial infarction. JAHA. 2016;5(6):e003418. https://www.ahajournals.org/doi/10.1161/JAHA.116.003418
4. ECG differences and ECG predictors in patients presenting with ST segment elevation due to myocardial infarction versus takotsubo syndrome. IJC Heart & Vasculature. 2022;40:101047. https://www.sciencedirect.com/science/article/pii/S2352906722000963