Preconditioning reduces QTc value in patients with first non-ST-segment elevation myocardial infarction (NSTEMI).
BACKGROUND
Preinfarction angina (PA) consists a strong clinical correlate to ischemic preconditioning (PC) and seems to occur in a bimodal time course. The aim of the study is to evaluate the impact of both forms of PC on QTc value representing myocardial electric stability, in patients with a first NSTEMI.


METHODS
Forty-eight patients, with first NSTEMI and poor or no collateral development were enrolled in the study. QTc at admission and discharge were recorded. All patients had comparable admission QTc values and were divided into three groups according to the absence or presence and exact timing of preinfarction angina. The first group consisted of 20 patients who did not report PA (PA-, representing no PC effect); the second group of 12 patients with reported PA within 12 hours prior to admission (12h PA+, representing the classic form of PC); and the third group of 16 patients reporting PA within 12 to 48 hours prior to admission (48-hour PA+, representing the delayed form of PC). The primary outcome was determined as the effect of PA on QTc value at discharge.


RESULTS
Discharge QTc values were significantly reduced in both (PA+) groups compared to (PA-) group (412 +/- 50 vs. 455 +/- 53 ms, p = 0.015 and 417 +/- 29 vs. 455 +/- 53 ms, P = 0.033, respectively). Both groups of (PA+) patients compared to (PA-) patients suffered no arrhythmic events during their hospitalization (0/12 vs. 6/20, P = 0.04 and 0/16 vs. 6/20, P = 0.02).


CONCLUSIONS
Both forms of preconditioning, similarly and significantly reduce QTc value at discharge in patients experiencing a first NSTEMI, suggesting possible protection from future arrhythmic events.
D000328:Adult; D000704:Analysis of Variance; D000789:Angina, Unstable / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy*; D015906:Angioplasty, Balloon, Coronary / Q000379:methods; D002316:Cardiotonic Agents / Q000627:therapeutic use; D016009:Chi-Square Distribution; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000379:methods; D004562:Electrocardiography; D005260:Female; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000517:prevention & control* / Q000628:therapy*; D009204:Myocardial Revascularization / Q000379:methods; D011336:Probability; D011379:Prognosis; D018570:Risk Assessment; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome
D002316:Cardiotonic Agents