Comparisons of QTd and QTcD and Arrhythmia Prevalence Between Fibrinolytic Therapy and Primary Percutaneous Coronary Intervention

The inter-lead variations in the measurements of the QT interval reflect regional variations in ventricular repolarization. This increased dispersion results in susceptibility to ventricular arrhythmias.  

We reviewed the medical records of 60 patients with ST-segment-elevation myocardial infarction (STEMI) over the last 6 years who received thrombolytic therapy (30 cases) or underwent primary percutaneous coronary intervention (PCI) (30 cases) in Ghaem Hospital and Emam Reza Hospital in Mashhad, Iran. The patients’ demographic characteristics, risk factors, treatment success, QTd and QTcD before and 24 hours after treatment, arrhythmias, and echocardiographic information were analyzed. Statistical analysis was conducted using the SPSS software, version 22, and a P value of less than 0.05 was considered statistically significant.  

The success rates (50% reduction in ST-segment elevation) of primary PCI and thrombolytic therapy were 66.66% and 33.33%, respectively. In addition, QTd and QTcD were significantly decreased in both successful procedures (P = 0.04 and 0.03, respectively). However, no significant difference in the variations of QTd and QTcD was seen between the 2 successful procedures (P = 0.91 and P = 0.87, respectively). Further, ventricular arrhythmias were evident in 36.6% of the patients with thrombolytic therapy, but no ventricular arrhythmia was observed in those who underwent primary PCI.  

QTd and QTcD were identified as useful predictors of ventricular arrhythmias. A significant reduction in QTd and QTcD in both successful procedures was evident, leading to a decrease in ventricular arrhythmias. Moreover, the success rate of primary PCI was higher than that of thrombolytic therapy. Therefore, primary PCI was identified as a more appropriate procedure for STEMI. (Iranian Heart Journal 2020; 21(3): 15-24)