Potential Effects of Ischemic Postconditioning and Changes in Heat Shock Protein 72 in Patients with Acute Myocardial Infarction without Prodromal Angina

Abstract

The effectiveness of ischemic postconditioning (iPoC) in patients with ST-elevation myocardial infarction (STEMI) without ischemic preconditioning has not been determined. Therefore, we investigated the impact of iPoC and its potential mechanism related to heat shock protein 72 (HSP72) induction on myocardial salvage in patients with STEMI without prodromal angina (PA).

We retrospectively analyzed data from 102 patients with STEMI with successful reperfusion among 323 consecutive patients with acute coronary syndrome. Among these, 55 patients with iPoC (iPoC (+) ) underwent 4 cycles of 60-second inflation and 30-second deflation of the angioplasty balloon. Both the iPoC (+) and iPoC (-) groups were divided into 2 further subgroups: patients with PA (PA (+) ) and those without (PA (-) ). We analyzed HSP72 levels in neutrophils, which were measured until 48 hours after reperfusion. I-123 β-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) scintigraphy was performed within a week of reperfusion therapy. In 64% of patients, thallium-201 (TL) scintigraphy was performed 6-8 months after STEMI onset.

Using BMIPP and TL, in the PA (-) subgroups, the iPoC (+) group had a significantly greater myocardial salvage ratio than the iPoC (-) group. iPoC was identified as an independent predictor of the myocardial salvage ratio. The HSP72 increase ratio was significantly elevated in the iPoC (+) PA (-) group. Importantly, the myocardial salvage effect in patients without PA was significantly correlated with the HSP72 increase ratio, which was greater in patients with iPoC.

These results suggest the potential impact of iPoC via HSP72 induction on myocardial salvage; however, the effects may be limited to patients with STEMI without PA.