[Diagnostic value of left bundle branch block in patients with acute myocardial infarction. A prospective analysis].

Background: In contemporary practice with early catheterization in most patients with suspected acute myocardial infarction, the clinical utility of new or presumably new left bundle branch block (LBBB) as a diagnostic criterion equivalent to ST-segment elevation is not well established. This study therefore aimed to determine the predictive value of LBBB for the diagnosis of acute transmural myocardial infarction (or ST-segment elevation myocardial infarction, STEMI).
Patients and Methods: Between November 2006 and December 2011, 1,139 consecutive patients presenting to the heart center of the University of Cologne with suspected STEMI were examined. Of these patients, 935 presented with ST elevation, 72 with LBBB, and 132 had neither of these ECG changes. The diagnosis was confirmed with immediate coronary angiography.
Results: Compared with ST-segment elevation, LBBB was associated with a higher prevalence of cardiovascular risk factors and end-organ damage, and more patients with LBBB presented with pulmonary edema or cardiogenic shock (Killip III/IV). STEMI was confirmed in 58.3 % of patients with LBBB and in 86.4 % with ST-segment elevation. The sensitivity (0.38 [0.29-0.46]; odds ratio: 1.24) and specificity (0.67 [0.58-0.77]) of LBBB for the prediction of STEMI were low. However, the additional assessment of troponin T (> 0.1 µg/l) increased the predictive value of LBBB significantly. After adjusting for age and gender, no difference in mortality was found between the groups.
Conclusion: LBBB with acute chest pain characterizes a cohort of patients with high morbidity and mortality. For the triage of these patients at first contact, additional criteria should be evaluated, which could increase the specificity of LBBB for the diagnosis of STEMI.