The goal of this study was to evaluate the effect of preconditioning on out-of-hospital
ventricular fibrillation (VF) in patients with acute myocardial infarction (AMI).
More than half of the deaths associated with AMI occur out of the hospital and within
1 h of symptom onset. In humans, preinfarction angina (PA), which can serve as a surrogate
marker for preconditioning, reduces infarct size, but the protective effect against
out-of-hospital VF has not been investigated.
Preinfarction angina status and acute coronary angiographic findings of 72 consecutive
patients with AMI complicated by out-of-hospital VF were compared with 144 matched
controls without this complication.
Preinfarction angina is associated with a lower risk for VF (odds ratio [OR]: 0.40,
95% confidence interval [CI]: 0.18 to 0.88). In patients with acute occlusion of the
left coronary artery (LCA) (n = 136), the risk reduction is pronounced (OR: 0.25,
95% CI: 0.10 to 0.66), whereas, in patients with acute occlusion of the right coronary
artery (RCA) (n = 67), the protective effect of PA on VF was not observed (OR: 2.25,
95% CI: 0.45 to 11.22). Subgroup and multivariate analyses show that the protective
effect is independent of cardiovascular risk factors, preinfarction treatment with
beta-adrenergic blocking agents or aspirin, the presence of collaterals or residual
antegrade flow or the extent of coronary artery disease.
Preinfarction angina protects against out-of-hospital VF in patients with acute occlusion
of the LCA. This protection is independent of risk factors or coronary anatomy. A
larger study is needed to examine the apparently different effect in patients with
acute occlusion of the RCA.