Catheter ablation for supraventricular tachycardias: contemporary issues.

The treatment of cardiac arrhythmias has evolved significantly over the last 30 years. Understanding of arrhythmia mechanisms has led to pharmacologic therapies, surgical interventions and the widely used percutaneous catheter ablation techniques. The focus of this review is centered on the current catheter ablation therapies available for supraventricular tachycardia. We will discuss current management strategies including challenges when considering catheter ablation therapy for management of supraventricular tachycardias: atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia utilizing an accessory pathway, atrial tachycardia and atrial flutter. Selected contemporary issues related to supraventricular tachycardia physiology, ablation approaches and ablation outcomes and complications will be discussed. Future goals for electrophysiologists are to continue to improve procedural safety and efficiency, while maintaining the impressive success rates that have been achieved.

Predicting irreversible left ventricular dysfunction after acute myocardial infarction.

Patients with reduced left ventricular ejection fractions (LVEFs) and previous myocardial infarctions or heart failure are at increased mortality risk. Implantable cardioverter-defibrillators may mitigate this risk. The aim of this study was to identify patient characteristics at the time of presentation with ST elevation myocardial infarction (STEMI) that predict irreversible left ventricular dysfunction. From January 2003 to December 2005, patients presenting with STEMIs and an LVEFs after percutaneous coronary intervention or=90 days. Multivariate analysis identified post-percutaneous coronary intervention LVEF I (odds ratio 4.4, 95% confidence interval 1.5 to 12.6, p = 0.006), and Q waves on postrevascularization electrocardiography (odds ratio 6.3, 95% confidence interval 1.5 to 26.5, p = 0.011) to be significantly more common in the group with LVEFs or=90 days. The presence of all 3 factors, present in 14 patients (12%), had a positive predictive value of 100% that LVEF would be or=90 days. In conclusion, in patients with STEMIs referred for catheterization, a post-percutaneous coronary intervention LVEF I, and pathologic Q waves after revascularization each predicted that the LVEF measured at >or=90 days would remain

The immediate and short-term effect of successful percutaneous coronary intervention on repolarization in acute myocardial infarction patients.

OBJECTIVES: The primary objective was to assess the immediate and short-term impact of successful percutaneous coronary intervention (PCI) on QT dispersion (QT disp) and corrected QT dispersion (QTc disp). Secondarily, the impact of PCI on QT and QTc disp within different infarct-related arteries and the impact of successful PCI in these different arteries were evaluated. METHODS: Patients (n = 140, age 61.6 +/- 12.9, 69% male) undergoing direct primary PCI for acute MI were evaluated. Twelve-lead ECGs were obtained before (baseline), immediately after (0 h), 24hours after, and 3 days after PCI. The QT and QTc interval in each of the 12-leads were measured and the shortest interval was subtracted from the longest to derive the QT disp and QTc disp, respectively. RESULTS: Angiography showed blockages in the left anterior descending, right coronary artery, and circumflex in 37.1, 48.9, and 15.0% of patients, respectively. Overall, 97 patients achieved successful reflow. QT and QTc disp were significantly improved in the group with successful reflow at each follow-up time after PCI versus baseline and corresponding values in the unsuccessful reflow group. QT disp was improved among patients with successful reflow irrespective of which infarct artery was responsible for the acute myocardial infarction. CONCLUSIONS: Successful reflow with PCI is associated with a rapid reduction in QT disp and QTc disp that is maintained for at least 3 days after the event. Conversely, unsuccessful reflow was not associated with significant reductions in QT or QTc disp.