Wednesday, July 24, 2013

New LBBB or Presumed New LBBB to be treated as STEMI??

The dictum of "New LBBB or 'PRESUMED' (dangerous!) new LBBB should be treated as a STEMI" in many clinical practice guidelines (CPGs) including the Malaysian STEMI are simply NOT true! I hope that future CPGs would change this.

For example, Chang et al (2009) showed that the incidence of STEMI in new LBBB is only 7% and....this is not statistically different from OLD LBBB which in not statistically different from NO LBBB!

Conclusion: The presence of LBBB, whether new or old, did NOT predict AMI.
That's why Sgarbossa's criteria (and now, Smith's modification of Sgarbossa's criteria are needed to improve the sensitivity of picking up STEMI).

Chang AM, Shofer FS, Tabas JA, Magid DJ, McCusker CM, Hollander JE. Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients. Am J Emerg Med. 2009 Oct;27(8):916-21.

In another retrospective analysis of data from patients in the Mayo Clinic's ST-segment elevation myocardial infarction network from July 2004 to August 2009, out of 892 patients analyzed, 36 (4%) of whom had new LBBB. And only 14 (39%) of these 36 patients had final diagnoses of acute coronary syndromes, of which 12 were AMI, while 13 (36%) had cardiac diagnoses other than acute coronary syndrome and 9 (25%) had noncardiac diagnoses.

(Ref: Utility of Left Bundle Branch Block as a Diagnostic Criterion for Acute Myocardial Infarction " published In American Journal of Cardiology, Vol 107, Issue 8, 15 April 2011)

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