Differentiating typical tako tsubo syndrome from extensive anterior ST-elevation myocardial infarction: look behind the anterior wall
Authors: Pernigo M , Berti M , Dinatolo E , Campana M , Cuccia C 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.
Tako-Tsubo Syndrome (TTS) consists in transient left ventricular dysfunction resembling in its typical form acute anterior ST-elevation myocardial infarction (STEMI). Early non-invasive differential diagnosis, crucial for therapeutic purposes, appears difficult according to available data.

Purpose
to systematically analyze LV function and ECG changes in patients with acute anterior STEMI and TTS, to identify parameters possibly useful for differential diagnosis.

Methods
this is a retrospective cohort study, with 2 groups: patients with anterior STEMI and extensive apical involvement at echocardiography (n = 22); patients with TTS (n = 22) and ECG changes diagnostic for anterior STEMI at presentation (n = 22). They underwent a comprehensive clinical and echocardiographic evaluation in acute phase, including 2D speckle tracking longitudinal strain. We created new indexes based on wall motion impairment of inferior and inferior-lateral walls: the Inferior apex ratio (IAR) and inferior-lateral apex ratio (ILAR) (see picture).

Results
TTS and STEMI patients were similar for age (74.7 ± 9.1 vs 73.4 ± 14.1 y), sex, and main biochemical data except for higher peak troponin I in STEMI (1323 ± 622 vs 377 ± 220 ng/L, p = 0.01). ST segment elevation in V1 (V1e) was significantly less common in TTS (p &lt; 0.001) while increased ratio of ST segment elevation in V4-V6 to V1-V3 (∑Ste V4-V6/∑Ste V1-V3≥1) was more common in TTS (p &lt; 0.001). Among ECG parameters, absence of V1e had the best sensitivity (86%) and specificity (86%) in predicting TTS. LVEF values were similar (means: 45% in both groups) with EDVI greater in TTS (55.5 ±12.3 vs 46.6 ± 11.0 ml/m2, p = 0.02). WMSI was greater in TTS patients (2.2 ± 0.1 vs 1.9 ± 0.1, p &lt; 0.0001), mainly for greater scores of mid segments. Global longitudinal strain was impaired in TTS (-8.1 ± 2.5 %) and in anterior STEMI (-7.9 ± 2.7, p = 0.8). By analyzing the single segments, strain was significantly more compromised in TTS in mid inferior (MI) (-4.3 ± 6.4 vs -9.9 ± 5.5 % in STEMI, p = 0.003) and mid inferior-lateral (MIL) segments (-5.4 ± 5.4 vs -9.6 ± 4.9 %, p = 0.009). Mean IAR was 0.7 ± 0.3 in TTS vs 1.8 ± 0.6 in STEMI, p &lt; 0.0001; mean ILAR was 0.7 ± 0.1 in TTS vs 2.0 ± 0.9 in STEMI, p &lt; 0.0001. ILAR was &lt; I in all TTS patients, and &gt; 1 in all STEMI cases. IAR &lt; 1 showed 90% sensitivity and 95% specificity in predicting TTS. By multivariate linear regression analysis, strain values of MI and MIL segments were significantly associated with TTS (Beta: -0.98 and -0.97 respectively, p &lt; 0.0001), independently from age, sex, and EDVI. IAR and ILAR values were significantly associated with TTS (Beta: -0.81 and -0.76 respectively, p &lt; 0.0001) independently from the same co-variates as above.

Conclusions
evidence of impaired contractility extending beyond apex to mid inferior and inferior-lateral walls, assed by longitudinal strain or by IAR and ILAR, can help to discriminate TTS from extensive anterior STEMI, more accurately than ECG parameters. Abstract Figure. Examples of ILAR index Abstract Figure. IAR and ILAR distributions