Friday, November 16, 2012

Don't ß-Blockade Cocaine Chest Pain

Or, specifically, ignore this evidence that says you can.

There may be some mythology to the hypothesis that non-selective ß-receptor blockade is contraindicated in the setting of cocaine chest pain.  After all, the supporting evidence consists only of small, laboratory case series – and other outcomes-oriented data suggests ß-blockade is cardioprotective, as we already know.  However, this study is a perfect example of inappropriately extending a conclusion from retrospective data.

These authors identified 378 patients from retrospective chart review, selecting patients with chief complaints of chest pain and positive toxicology tests for cocaine.  Unfortunately, urine toxicology tests for cocaine stay positive for days following the initial episode of cocaine use.  Therefore, there is no way from these chart review methods to reliably differentiate the acuity of the cocaine intoxication.  

This is important because a major flaw in retrospective reviews, such as this, is a confounding selection bias.  If all cocaine chest pain patients are not created equal – the neurohormonal effects of cocaine last on the minutes to hours while their drug tests are positive for days – then providers may be selecting patients for beta blocker use/non-use based on acuity information this review cannot detect.  If providers are excluding patients from beta-blockers based on the acuity of their intoxication – as many sensible providers might – and only using beta-blockers in non-acute presentations, then this study may not include any of the population of interest.

The authors' statement of "We have found that BB use in the acute management of cocaine-associated chest pain did not increase the incidence of MI" cannot be defended as accurate, as it is based on indefensible assumptions.

"Safety of β-blockers in the acute management of cocaine-associated chest pain"
http://www.ncbi.nlm.nih.gov/pubmed/23122421

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