Decreased prevalence of late potentials with mechanical versus thrombolysis-induced reperfusion in acute myocardial infarction

Effects of reperfusion obtained two to six months after acute myocardial infarction on myocardial electrical stabilization in patients with an occluded infarct-related coronary artery

To assess the changes in electrical stability markers in patients with previous myocardial infarction after very late reopening of the infarct-related artery, we studied QT dispersion, corrected-QT dispersion, and late potentials before and 1, 3, and 6 months after an attempt at late percutaneous coronary intervention (PCI) in 31 consecutive patients with single-vessel disease (infarct-related artery occlusion or subocclusion) diagnosed > or = 4 weeks after the ST-elevation myocardial infarction. Patients underwent PCI 3.9 +/- 2 months after ST-elevation myocardial infarction. PCI was successful in 24 patients (group A) and unsuccessful in 7 (group B). The 2 groups were similar in clinical and angiographic characteristics, as well as the prevalence of basal late potentials, average QT dispersion, and corrected-QT dispersion. One month after PCI, the successful reperfusion group had a significant 67% decrease in the prevalence of late potentials and average QT dispersion and corrected QT dispersion (51 +/- 9 vs 72 +/- 11 ms, p <0.00001, and 51 +/- 10 vs 76 +/- 15 ms, p <0.00001, respectively). These benefits remained stable at 3 and 6 months after PCI. Conversely, the unsuccessful group did not show any improvement in electrical stability markers after PCI failed. Thus, reperfusion obtained very late after ST-elevation myocardial infarction confers significant electrical stabilization that may contribute to a better outcome in patients with patent infarct-related arteries.

Reduced prognostic power of ventricular late potentials in post-infarction patients of the reperfusion era

AIMS

To test the prognostic value of ventricular late potentials (LPs) in a large cohort of post-infarction patients in the modern reperfusion era.

METHODS AND RESULTS

1800 consecutive survivors of acute myocardial infarction in sinus rhythm and under 76 years of age were enrolled. Many (99%) of the patients received reperfusion/revascularization therapy (91% percutaneous coronary intervention) and up-to-date pharmacological treatment (99% aspirin, 93% beta-blockers, 90% ACE-inhibitors, and 85% statins). LPs were calculated in 968 patients and found to be present in 90 (9.3%). The primary endpoint was the composite of cardiac death and serious arrhythmic events. The secondary endpoint was the composite of sudden cardiac death and serious arrhythmic events. During follow-up (median 34 months), 26 patients reached the primary endpoint. The presence of LPs was not significantly associated with the primary endpoint in univariable or multivariable analysis. In contrast, low (< or = 30%) left ventricular ejection fraction (hazard ratio 9.6, 95% confidence interval 4.1-22.4), heart rate turbulence category 2 (7.5, 2.4-23.9) and category 1 (5.3, 1.9-14.9) were significant predictors in both univariable and multivariable analysis.

CONCLUSION

Ventricular LPs are of limited use for risk stratification in unselected post-infarction patients in the modern reperfusion era.

Effect of infarct-related artery patency and late potentials on late mortality after acute myocardial infarction

OBJECTIVE

To assess the effect of patency of the infarct-related artery and the presence of late potentials on late cardiac mortality after myocardial infarction.

MATERIAL AND METHODS

We studied the influence of the infarct-related artery patency and the presence of late potentials during signal-averaged electrocardiography on late mortality in 124 survivors of acute myocardial infarction. In addition, we assessed predictive factors of cardiac mortality by univariate and multivariate statistical analysis.

RESULTS

A study group of 98 men and 26 women (mean age, 59 years) who were survivors of acute myocardial infarction underwent follow-up for a mean of 3.6 +/- 1.0 years. Immediate reperfusion therapy (thrombolysis or direct angioplasty) was accomplished in 71 patients (57%). During follow-up, 13 cardiac-associated deaths occurred. Infarct-related artery patency was strongly associated with improved survival, but the presence of late potentials did not correlate with increased mortality, even among patients with impaired left ventricular function. Univariate and multivariate analyses identified occluded infarct-related arteries, prior myocardial infarction, reduced left ventricular ejection fraction, and advanced age, but not late potentials, as predictors of increased late cardiac mortality.

CONCLUSION

These data suggest that coronary angiography may, but signal-averaged electrocardiography may not, identify patients with increased late risk of cardiac-related death after myocardial infarction. The low mortality among patients who have undergone successful reperfusion therapy may reduce the ability of noninvasive tests to distinguish between high- and low-risk patients.