Traditional teaching would suggest that any new or presumed new left bundle branch block (LBBB) on ECG in a patient with chest pain (or chest pain equivalent) should be managed like an ST-elevation MI. There has been considerable amount of published literature on the subject. A well-known but somewhat controversial set of criteria (Sgarbossa) was established to aid the clinician in differentiating between the patients with LBBB that require and don’t require urgent ACS management (thrombolytics or emergent coronary catheterization). Studies have suggested that the Sgarbossa criteria are far from perfect with a sensitivity of 78% and a specificity of 90%.
In the pre-hospital setting, protocols have been implemented that suggest a new/presumed new LBBB in a suspected ACS should be treated like a STEMI. But recent data do not support this universal approach as many of these patients with suspected ACS and LBBB are not having an acute MI. So treating these patients as if they’re having a STEMI could put them at an unnecessary risk either from the complications of thrombolysis or coronary cathetherization. In pre-hospital settings where thrombolytics are actually administered, appropriate diagnosis is essential. In our setting in Auckland we’re not administering pre-hospital thrombolytics but this discussion remains important. Especially since we notify our receiving hospital that we have a patient who with suspected ACS (possibly STEMI). Furthermore, if we suspect a STEMI, we will re-route to a centre capable of performing coronary catheterizations. Such decisions may occur while also considering weather factors and time to hospital.
A recent publication has proposed a very reasonable algorithm to aid the clinican in managing the patient with suspected ACS and a LBBB. Check it out for yourself.
Maybe this is what’s being done already…but its finally nice to see something in the cardiology literature that provides a bit more guidance in managing these challenging patients. This is something that all ED physicians can keep on the smartphones and at least use this when they speak with the cardiologist on-call. Interestingly, the authors then go on to suggest the demotion of the class I level of evidence that new LBBB be treated as a STEMI equivalent.
Basically, this would remove suspected ACS + new LBBB as an automatic STEMI equivalent thus having considerable impact on the pre-hospital and in-hospital management of these patients.