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Revista Española de Cardiología (English Edition) Revista Española de Cardiología (English Edition)
Rev Esp Cardiol. 2017;70:559-66 - Vol. 70 Num.07 DOI: 10.1016/j.rec.2016.11.017

Assessment of Smith Algorithms for the Diagnosis of Acute Myocardial Infarction in the Presence of Left Bundle Branch Block

Andrea Di Marco a,, Ignasi Anguera a, Marcos Rodríguez a, Alessandro Sionis b, Antoni Bayes-Genis c, Jany Rodríguez d, Albert Ariza-Solé a, José Carlos Sánchez-Salado a, Mario Díaz-Nuila b, Mónica Masotti d, Roger Villuendas c, Paolo Dallaglio a, Joan Antoni Gómez-Hospital a, Ángel Cequier a

a Área del Corazón, Servicio de Cardiología, Hospital Universitario de Bellvitge, Barcelona, Spain
b Servicio de Cardiología, Hospital de Sant Pau, Barcelona, Spain
c Servicio de Cardiología, Hospital Universitario Germans Trias i Pujol, Badalona, Barcelona, Spain
d Servicio de Cardiología, Hospital Clínic, Barcelona, Spain

Keywords

Left bundle branch block. Electrocardiography. Myocardial infarction. Primary percutaneous coronary intervention.

Abstract

Introduction and objectives

Recently, a new electrocardiography algorithm has shown promising results for the the diagnosis of acute myocardial infarction in the presence of left bundle branch block (LBBB). We aimed to assess these new electrocardiography rules in a cohort of patients referred for primary percutaneous coronary intervention (pPCI).

Methods

Retrospective observational cohort study that included all patients with suspected myocardial infarction and LBBB on the presenting electrocardiogram, referred for pPCI to 4 tertiary hospitals in Barcelona, Spain.

Results

A total of 145 patients were included. Fifty four (37%) had an ST-segment elevation myocardial infarction (STEMI) equivalent. Among patients with STEMI, 25 (46%) presented in Killip class III or IV, and in-hospital mortality was 15%. Smith I and II rules performed better than Sgarbossa algorithms and showed good specificity (90% and 97%, respectively) but their sensitivity was 67% and 54%, respectively. In a strategy guided by Smith I or Smith II rules, 18 (33%) or 25 (46%) patients with STEMI would have not received a pPCI, respectively. Moreover, the severity and prognosis of STEMI patients was similar regardless of the positivity of Smith rules. Cardiac biomarkers were positive in 54% of non-STEMI patients, limiting their usefulness for initial diagnostic screening.

Conclusions

Diagnosis of STEMI in the presence of LBBB remains a challenge. Smith rules can be useful but are limited by suboptimal sensitivity. The search for new electrocardiography algorithms should be encouraged to avoid unnecessary aggressive treatments in the majority of patients, while providing timely reperfusion to a high-risk subgroup of patients.

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1885-5857/© 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved