Traditional teaching for many years has been that new or presumed new LBBB in patients with anginal type of symptoms should be treated as a STEMI, i.e. with immediate PCI or lytics. However, that teaching is based on poor evidence. Newer, increasing evidence is suggesting that new/presumed new LBBB in patients with anginal symptoms is actually not associated with acute MI any more often than when a patient has an old LBBB with those symptoms.
Probably the best management in patients with anginal type of symptoms and a new/presumed new LBBB is to contact the cardiologist on call and ask them for their preference in terms of treatment. Those patients are not necessarily definite AMIs.
References
1. Kontos MC, et al. Outcomes in patients with chronicity of left bundle-branch block with possible acute myocardial infarction. Am Heart J 2011;161:698-704. 2. Jain S, et al. Utility of left bundle branch block as a diagnostic criterion for acute myocardial infarction. Am J Cardiol 2011;107:1111-1116. 3. Chang AM, et al. Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients. Am J Emerg Med 2009;27:916-921.
