Performance of electrocardiographic criteria to differentiate Takotsubo cardiomyopathy from acute anterior ST elevation myocardial infarction

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Abstract

Background

The initial electrocardiogram (ECG) in Takotsubo cardiomyopathy (TC) can mimic an acute, anterior ST-segment elevation myocardial infarction (STEMI). Given the profound and immediate treatment differences between TC and STEMI, it would be clinically valuable to distinguish them using ECG criteria.

Methods

Presenting ECGs for proven cases of TC and acute, anterior STEMI were retrospectively collected. QRS onset and J-point were manually identified using custom software to compute median ST deviation for each lead. Six published ECG criteria were examined for diagnostic accuracy using the clinical diagnosis as the gold standard.

Results

33 TC and 263 acute, anterior STEMI cases were identified. ST-segment deviation differed significantly between groups for all leads except aVR, I, V5, and V6. All six published ECG criteria showed a marked reduction in diagnostic accuracy in our validation cohort, except for a combination of ST-elevation in leads V2 < 1.75 mm and V3 < 2.5 mm (sensitivity 79%, specificity 73% for TC).

Conclusion

Our study demonstrates the limited diagnostic accuracy of published ECG rules to distinguish TC from acute, anterior STEMI. Given the rarity of TC and the clinical consequences of a “false positive” TC diagnosis based on ECG criteria alone, such rules should not be used in practice. TC remains a diagnosis of exclusion after emergent angiography in patients with an acute coronary syndrome and significant ST-segment elevation.

Introduction

Takotsubo cardiomyopathy (TC), alternatively called stress cardiomyopathy, ampulla cardiomyopathy, transient left ventricular apical ballooning syndrome, or broken heart syndrome, represents 1–2% of acute coronary syndrome presentations [1]. The initial electrocardiogram (ECG) usually demonstrates ST-segment elevation, most frequently in the anterior leads [2]. However, angiography demonstrates an absence of obstructive disease or acute plaque rupture [3]. Care is supportive and full recovery of ventricular function is usually seen within a few months [4], [5].

Given the profound and immediate treatment differences between TC and an acute ST-segment elevation myocardial infarction (STEMI), it would be clinically valuable to distinguish them using ECG criteria. Several groups have proposed ECG rules [6], [7], [8], [9] but their diagnostic utility has been questioned [10], [11]. Therefore, we investigated the diagnostic accuracy of ECG criteria to distinguish between TC and an acute, anterior STEMI.

Section snippets

Materials and methods

The Northwestern Memorial Hospital institutional review board approved this retrospective study. Patients with TC were identified between June 2003 and December 2009 from a systematic review of admissions to the coronary care unit and acute cases in our cardiac catheterization laboratory. All cases met diagnostic criteria [4], [5], every case underwent diagnostic catheterization within 24 h of presentation, and all angiogram and ventriculogram images were reviewed.

Patients with an acute anterior

Results

We identified 33 patients with TC and 263 patients with an acute, anterior STEMI. Table 1 compares the demographic, admission laboratory, and ECG findings between groups. Females comprise a vast majority of TC patients but a minority of STEMI. Peak cardiac enzyme levels were significantly lower in the TC group. No significant racial differences exist between groups, but TC patients were older, on average.

Table 1 also summarizes ST-segment deviations in both groups, which are shown as boxplots

Discussion

Our findings show limited diagnostic accuracy for ECG prediction rules distinguishing between Takotsubo cardiomyopathy and an acute, anterior STEMI. Table 2 compares the diagnostic accuracy in the current study to those reported in the literature. Diagnostic accuracy was markedly lower in our validation cohort than the derivation cohort for all prediction rules except STeV2 < 1.75 mm and STeV3 < 2.5 mm (derivation sensitivity 67%, specificity 94%, compared to validation sensitivity 79%, specificity

Conclusion

Based on recent epidemiologic data, the pre-test probability of TC for a patient with an acute coronary syndrome is 1–2% [1]. To comfortably withhold emergent angiography when the ECG meets ST-segment elevation criteria, a clinical decision rule would have to increase the pre-test probability greatly. Even the best validated rule in our cohort would only increase a 2% pre-test probability to 5% afterwards and thereby falsely classify 27% of patients with STEMI as a TC. Given the enormous

Acknowledgment

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology.

References (16)

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    The diagnostic accuracy for the ST-segment based ECG features analyzed in this study were not high enough to be able to differentiate patients with TC from patients with an acute anterior STEMI (Table 2) with enough certainty to not perform invasive coronary angiography (CAG). The existing ECG criterion [6] analyzed in this study was compared to the original study [6] and a recent study performed by Johnson et al. [13]. The sensitivity found in the original study was 91%, while in both our study and the study performed by Johnson et al. the sensitivity was markedly lower (26% and 0% respectively), while the specificity was similar.

  • Transient QRS amplitude attenuation is associated with clinical recovery in patients with takotsubo cardiomyopathy

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    While coronary angiography is still mandatory in order to differentiate between TC and ACS [5], a wide array of diagnostic modalities has been proposed as potentially useful in strengthening clinical suspicion [6]. The electrocardiogram (ECG), despite being the first test used in acute settings, still lacks diagnostic accuracy, as no specific ECG signs distinguishing TC from ACS have been described yet [7–12]. Moreover, ST segment or T wave alterations change rapidly during the first hours, making them unreliable diagnostic markers during the acute and sub-acute phases [12].

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