Outcomes in patients with chronicity of left bundle-branch block with possible acute myocardial infarction
Section snippets
Methods
The chest pain protocol used at our institution has been described in detail previously.12 Patients with possible myocardial ischemia undergo an evaluation by emergency department (ED) physicians, with further treatment and evaluation dictated based on the initial risk stratification.12 Patients were included in this analysis if they presented with possible myocardial ischemia, underwent serial marker assessment, and had an LBBB on the initial ED ECG. Data were collected prospectively as part
Clinical characteristics
From 1994 to 2009, 401 consecutive patients who underwent evaluation for possible acute coronary syndrome had LBBB on the initial ECG and were included in this analysis. In general, the patient population was older (median age 66 years), with frequent comorbidities (Table I). Ejection fraction (EF) was available in 360 patients (90%), of whom 76% had an EF <50% and with 61%, <40%.
A majority of patients (64%) had either a new LBBB (36%) or presumed new LBBB (28%). Clinical characteristics of
Discussion
We found that there was no difference in the incidence of MI based on the chronicity of the LBBB on the presenting ECG. Patients who had concordant ST changes had a high likelihood of MI. In addition, concordant ECG changes were the most important independent predictor of MI as well as an independent predictor of 30-day mortality.
Administration of fibrinolytic therapy to patients with AMI and ST-segment elevation decreases mortality.15 The results of the Fibrinolytic Collaborative Group, which
Limitations
Although patient data from an extended period were used, the criteria for emergent reperfusion in patients with LBBB have been present because guidelines were published in 1996. We used CK and CK-MB to estimate peak MI size because of the multiple different TnI assays used during the study period. In addition, use of CK and CK-MB allows comparison across other studies, a technique used in clinical trials.
Despite these limitations, our study has several strengths. These include the large
Conclusions
Most patients who present to the ED with possible AMI who have an underlying LBBB do not have an MI. In those who do, MI size is relatively small and therefore are unlikely to benefit from emergent reperfusion treatment. The diagnostic use of a new LBBB was low. Specific ECG criteria, concordant ST depression or elevation, had a high specificity and identified patients who had large MIs. The use of emergent reperfusion treatment in patients with new LBBB as a performance indicator should be
Disclosures
Funded, in part, from research funds from the Pauley Heart Center.
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2018, Clinical BiochemistryCitation Excerpt :While chronic LBBB has become more common, incident LBBB in MI has decreased [103]. Several studies have demonstrated no difference in the prevalence of MI between patients with presumably new or known LBBB, suggesting that true MI related LBBB is indeed rare [104,105]. Due to their high specificity, specific ECG criteria including Sgarbossa, Smith and Selvester criteria should be used to triage patients towards rule-in of MI and immediate coronary angiography such as patients with STEMI [106,107].
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