Randomized Trial of Primary PCI with or without RoutineManual Thrombectomy

During primary percutaneous coronary intervention (PCI), manual thrombectomymay reduce distal embolization and thus improve microvascular perfusion. Smalltrials have suggested that thrombectomy improves surrogate and clinical outcomes,but a larger trial has reported conflicting results.MethodsWe randomly assigned 10,732 patients with ST-segment elevation myocardial infarction(STEMI) undergoing primary PCI to a strategy of routine upfront manualthrombectomy versus PCI alone. The primary outcome was a composite of deathfrom cardiovascular causes, recurrent myocardial infarction, cardiogenic shock, orNew York Heart Association (NYHA) class IV heart failure within 180 days. The keysafety outcome was stroke within 30 days.ResultsThe primary outcome occurred in 347 of 5033 patients (6.9%) in the thrombectomygroup versus 351 of 5030 patients (7.0%) in the PCI-alone group (hazard ratio in thethrombectomy group, 0.99; 95% confidence interval [CI], 0.85 to 1.15; P = 0.86). Therates of cardiovascular death (3.1% with thrombectomy vs. 3.5% with PCI alone;hazard ratio, 0.90; 95% CI, 0.73 to 1.12; P = 0.34) and the primary outcome plusstent thrombosis or target-vessel revascularization (9.9% vs. 9.8%; hazard ratio,1.00; 95% CI, 0.89 to 1.14; P = 0.95) were also similar. Stroke within 30 days occurredin 33 patients (0.7%) in the thrombectomy group versus 16 patients (0.3%)in the PCI-alone group (hazard ratio, 2.06; 95% CI, 1.13 to 3.75; P = 0.02).ConclusionsIn patients with STEMI who were undergoing primary PCI, routine manual thrombectomy,as compared with PCI alone, did not reduce the risk of cardiovasculardeath, recurrent myocardial infarction, cardiogenic shock, or NYHA class IV heartfailure within 180 days but was associated with an increased rate of stroke within30 days. (Funded by Medtronic and the Canadian Institutes of Health Research;TOTAL ClinicalTrials.gov number, NCT01149044.

Nonsustained ventricular tachycardia in the setting of acute myocardial infarction: tachycardia characteristics and their prognostic implications.

BACKGROUND: Nonsustained ventricular tachycardia (NSVT) has significant prognostic implications in the setting of healing and healed myocardial infarction (MI), but only limited information is available on its importance in the setting of acute MI. We evaluated the prognostic significance of NSVT characteristics in the setting of acute MI. METHODS AND RESULTS: A prospective database was used to identify 112 patients with NSVT within 72 hours of acute MI. A control group was identified matched for age, sex, type of MI, and thrombolytic treatment. Mean age was 64 to 65 years in the 2 groups with 71% to 72% men. Q-wave MI was noted in 52% to 53%, and thrombolytic therapy was administered to 31% to 32% of patients in each group. In-hospital ventricular fibrillation occurred more frequently in the NSVT group (9% versus 0% in the control group; P<0. 001), but total in-hospital (10% versus 4%) and follow-up mortality (10% versus 17%) did not differ between the 2 groups. With a Cox regression model, specific NSVT characteristics were predictive of mortality. The strongest predictor was time from presentation to occurrence of NSVT. Shortest RR interval during NSVT was also a univariate predictor of mortality. Multivariate analysis identified time from presentation to occurrence of NSVT as the strongest predictor of mortality (P<0.0001). The increased relative risk of NSVT was first significant when it occurred 13 hours from presentation and continued to increase as the time from presentation to occurrence of NSVT increased, plateauing at approximately 24 hours with a relative risk of 7.5. CONCLUSIONS: Contrary to prevailing clinical opinion, NSVT that occurs in the setting of acute MI does have important prognostic significance. Specifically, the currently accepted notion that NSVT that occurs within 48 hours of acute MI has no prognostic significance needs to be adjusted. Although NSVT that occurs within the first several hours of presentation does not have an associated adverse prognosis, NSVT that occurs beyond the first several hours after presentation is associated with significant increases in relative risk.

Late recurrence of atrial flutter following radiofrequency catheter ablation.

The success rate for catheter ablation of atrial flutter has been reported to be approximately 90%, but recurrences are common and can be seen in up to 20% of cases. Most of these recurrences are seen within a few weeks following ablation. We report on a patient who developed a recurrence of type I atrial flutter 2 years after an initially successful radiofrequency catheter ablation procedure. Whether the recurrent atrial flutter is due to a new reentrant circuit resulting from slow progression of atrial disease or due to the changes produced by radiofrequency energy in the nearby myocardium is not clear. Further work to define the electrophysiological changes in the atrial myocardium produced by radiofrequency energy, as well as long-term follow-up of patients undergoing radiofrequency catheter ablation for atrial flutter may help in answering these questions.

Effects of autonomic stimulation and blockade on signal-averaged P wave duration.

OBJECTIVES: This study sought to evaluate the effects of autonomic stimulation and blockade on the signal-averaged P wave duration. BACKGROUND: Signal-averaged P wave duration has been shown to have prognostic implications for patients prone to develop atrial fibrillation, but autonomic influences on the signal-averaged P wave duration have not been studied. METHODS: In 14 healthy volunteers (8 men, 6 women; mean [ +/- SD] age 28.5 +/- 4.8 years, range 22 to 38), signal-averaged P wave duration was measured on day 1 at baseline, during sympathetic stimulation with infusions of epinephrine (50 ng/kg body weight per min) and isoproterenol (50 ng/kg per min), beta-blockade with propranolol (0.2 mg/kg) and autonomic blockade with propranolol followed by atropine (0.04 mg/kg). On a second day, 10 of the 14 subjects returned for repeat baseline recordings and recordings during parasympathetic blockade with atropine (0.04 mg/kg). Signal averaging was performed using a P wave template. Both unfiltered and filtered (least-squares fit filter with 100-ms window) P wave durations were measured. Day to day and interobserver variability were assessed by calculation of intraclass correlation coefficients. RESULTS: The mean ( +/- SD) baseline filtered P wave duration on day 1 was 141 +/- 10 ms. Isoproterenol infusion significantly shortened the P wave duration to 110 +/- 16 ms (p < 0.001), and epinephrine resulted in significant prolongation to 150 +/- 10 ms (p < 0.05). Beta-adrenergic blockade increased the P wave duration to 153 +/- 10 ms (p < 0.005). Autonomic blockade shortened the P wave duration to 143 +/- 16 ms (p < 0.05 vs. beta-blockade). On the second day, the mean baseline P wave duration was slightly longer (144 +/- 10 ms, p < 0.02). Parasympathetic blockade with atropine resulted in mild shortening of the P wave duration to 136 +/- 15 ms (p < 0.1). Interobserver reproducibility was excellent (intraclass correlation coefficient 0.99). Day to day reproducibility was good (intraclass correlation coefficient 0.56). CONCLUSIONS: The signal-averaged P wave duration is not a fixed variable because it may change significantly under different autonomic conditions. This has important implications for the application of this test to the heterogeneous population susceptible to atrial fibrillation.