Summary
Preinfarction angina and early reperfusion of the infarct-related artery are major
determinants of reduced infarct-size in patients with acute myocardial infarction.
The beneficial effects of preinfarction angina on infarct size have been attributed
to the development of collateral vessels and/or to post-ischemic myocardial protection.
However, recently, a relation has been found between prodromal angina, faster coronary
recanalization, and smaller infarcts in patients treated with rt-PA: those with preinfarction
angina showed earlier reperfusion (p = 0.006) and a 50% reduction of CKMB-estimated
infarct-size (p = 0.009) compared to patients without preinfarction angina. This intriguing
observation is consistent with a subsequent observation of higher coronary recanalization
rates following thrombolysis in patients with prodromal preinfarction angina compared
to patients without antecedent angina. Recent findings in dogs show an enhanced spontaneous
lysis of plateletrich coronary thrombi with ischemic preconditioning, which is prevented
by adenosine blockade, suggesting an antithrom-botic effect of ischemic metabolites.
Understanding the mechanisms responsible for earlier and enhanced coronary recanalization
in patients with preinfarction angina may open the way to new reperfusion strategies.
A vast number of studies, globally involving ≈17,000 patients with acute myocardial
infarction, have unequivocally shown that an infarction preceded by angina evolves
into a smaller area of necrosis compared to an infarct not preceded by angina (Table
1) (1). So far, preinfarction angina has been thought to have cardioprotective effects
mainly through two mechanisms: collateral perfusion of the infarctzone (2-4), and
ischemic preconditioning of the myocardium (5-7). Here we discuss a further mechanism
of protection represented by improved reperfusion of the infarct-related artery.
Key words
Prodromal angina - myocardial infarction - reperfusion - thrombolysis