Effect Of Grade Of Single-lead ST-segment Resolution On Clinical Prognosis And QTd In Acute Myocardial Infarction After Emergent Percutaneous Coronary Intervention

Objective: To study myocardial tissue reperfusion and effect of grade of single-lead ST-segment resolution on clinical prognosis and QTd in acute ST-segment elevated myocardial infarction(STEMI) after emergent percutaneous coronary intervention(PCI).Methods: Fifty-eight patients with a first STEMI successfully treated with emergent PCI within 12 hours after the onset of chest pain were selected from March, 2003 to December, 2005. 12-leads electrocardiograms were recorded before PCI and 90 minutes after PCI. According to the grade of single-lead ST-segment resolution, the cases were divided into group A: single-lead ST-segment resolution≥50%(34 cases) and group B: single-lead ST-segment resolution < 50%(24 cases). Left ventricular ejection fraction(LVEF) 3 months after PCI and incidence of death, reinfarction, congestive heart failure and ventricular arrhythmia were analysed, QT intervals were measured before PCI, 90 minutes and 24 hours after PCI respectively. QTd was calculated as the difference between the maximum and minimum QT interval (QTd = QTmax-QTmin).Results: 1. There was no difference in age, gender, infarct location and incidence of hypertension, diabetes, hyperlipemia, smoking between group A and group B. But onset-balloon time was lower in group A(4.66±2.44h) than in group B(6.92±3.22h), P<0.01.2. The number of patients with congestive heart failure was 5 cases in group A(5/34 14.7%) and 9 cases in group B(9/24 37.5%),P<0.05.The number of ventricular arrhythmia was 4 cases in group A(4/34 11.8%) and 9 cases in group B(9/24 37.5%), P<0.05. The number of death was 1 case in group A(1/34 2.9%) and 2 cases in group B(2/24 8.3%), P>0.05. The number of reinfarction was 1 case in group A(1/34 2.9%) and 3 cases in group B(3/24 12.5%), P>0.05.3. There was no difference in LVEF before PCI between group A(45.1±9.7)% and group B(44.9±8.1)%;LVEF was remarkably higher in group A(54.0±11.54)% than in group B(47.8±6.87)% three months after PCI (P<0.05).4. There was no difference in QTd before PCI between group A(68.6±21.6ms) and group B(65.2±20.8ms); QTd was(42.0±13.4ms) in group A and (59.4±19.3ms) group B 90 minutes after PCI (P<0.01); QTd was (33.1±11.8ms) in group A and (51.8±16.32ms) in group B 24 hours after PCI(P<0.01).Conclusion: 1. Single-lead STR can predict short-term major adverse cardiac events in STEMI after emergent PCI.2. There was correlation between Single-lead STR and the recovery of QTd.3. Single-lead and QTd STR were simple index to determine myocardial microcirculatory reperfusion.