Friday, August 3, 2012

Vancouver Chest Pain Rule in Tehran

Iran and Canada would be considered by most to be very different places.  However, from a cardiovascular standpoint, it seems they're not so disparate.

This is a prospective, validation study of the Vancouver Chest Pain Rule.  The Vancouver rule is one of many 2-hour accelerated rule-outs operating under the presumption that all disease can never be detected – sensitivity will never be 100%, but this assumes a context in which a discussion may be had with the patient about outpatient disposition.  Essentially, any patient under 40 years without a history of coronary artery disease and a normal EKG simply gets discharged.  Older than 40 and atypical chest pain is discharged either immediately after a CK-MB < 3.0 µg/L, or receives a 2-hour delta + repeat EKG if > 3.0 µg/L.  Essentially, the rule is designed only to ensure all unusual NSTEMIs are picked up.

In the initial study, the 30-day ACS rate for the discharged group was 1.2%.  In this Iranian study, the 30-day ACS rate of 292 very-low-risk patients is 1.3%.  Two of the four patients meeting criteria for discharge by CK-MB had positive troponins.  Considering CK-MB is nearly considered anachronistic now, most modern EDs would have not have discharged these patients based on troponin testing.  A third patient had EKG changes on the second EKG – which should fail the Vancouver rule, so I'm uncertain why it was included in their very-low-risk group.  Finally, the last patient had an entirely normal evaluation and a subsequent 70% lesion discovered on angiography a week later.  No mention of the hemodynamic significance/relation to ischemia of this lesion is noted.

A few hundred patients is hardly a definitive validation, but it's a nice demonstration that 50% of their cohort could have been discharged in two hours – and with the same 30-day event rate as the poor people being made to glow in the CCTA studies.

"Validation of the Vancouver Chest Pain Rule: A Prospective Cohort Study"

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