Ventricular Arrhythmias After AMI: A 20-Year Community Study
Ventricular Arrhythmias After AMI: A 20-Year Community Study
Background: Although myocardial infarction (MI) severity is declining, the occurrence of ventricular arrhythmia (VA) after MI and its effect on outcome is unknown. This study was undertaken to examine the frequency and timing of VA and the effect of VA on mortality after MI.
Methods: Myocardial infarctions recorded between 1979 and 1998 were validated. Baseline characteristics, occurrence of VA, and survival were determined. Ventricular arrhythmias were categorized as primary ventricular fibrillation (VF), nonprimary VF, and ventricular tachycardia (VT). Logistic regression was used to analyze associations between VA and baseline characteristics. Temporal trends were assessed with the Mantel-Haenszel χ. Survival was analyzed with the Kaplan-Meier method. Proportional hazards regression was used to examine the association between death and occurrence of VA.
Results: Among 2317 persons with incident MI, 7.5% experienced VA (3.6% nonprimary VF, 2.1% primary VF, 1.8% VT). Ventricular arrhythmia–associated factors were younger age, female sex, higher Killip class, ST elevation, and atrial fibrillation. Ventricular arrhythmias were associated with increased risk of death at 30 days.
Conclusion: Ventricular arrhythmias after MI are relatively common, particularly among persons with more severe MI and no prior history of coronary disease. Over time, the incidence of VF declined, whereas VT did not change. Ventricular arrhythmia after MI was associated with a 6-fold increase in morality. Thus, identification of high-risk MI survivors and prevention of VA could markedly improve outcomes. Further studies are needed to determine the cause of the shift in distribution of VA subtype.
Ventricular arrhythmias (VAs), including ventricular tachycardia (VT) and ventricular fibrillation (VF), are life-threatening complications of acute myocardial infarction (MI). The reported incidence of VF varies from 2.1% to 12.4%, depending on the population and duration of observation, and that of VT ranges from 1% to 9.9%. The incidence of both VF and VT in the same population has been reported to be 1.9% to 10.2%; however, these data are the result of a small number of studies because most reports detail the incidence of VT or VF but not both.
Although the literature suggests most VAs after MI occur within 48 hours, data are limited by the small number of studies that report timing of VA. Older age and higher Killip class have been consistently associated with the development of VAs after MI, although other variables such as male sex, hypertension and hypotension, conduction disturbances, location of MI, and tobacco use have also been associated with development of VA but are reported in far fewer studies. In addition, because most studies examining VA after MI report on only VT or VF, the predictors of any VA after MI are less well defined.
Ventricular arrhythmias adversely affect inhospital survival. However, whether VAs also negatively affect long-term survival is unclear. Although several studies examining long-term outcomes report no increased risk in death beyond hospitalization for the index MI, others report an excess in mortality at 1 year, depending upon the arrhythmia subtype. The discrepancies may arise because these studies include patients selected for clinical trials, a limited number of VA subtypes, and limited follow-up. Importantly, these data primarily reflect the long-term effect of VF, whereas the long-term effect of VT remains unknown.
As therapeutic approaches to MI change and the severity of incident MI declines, a parallel decrease in complications after MI is expected. Indeed, some evidence indicates that rates of recurrent MI, heart failure, and death after MI are diminishing. Population studies have observed decreases in the number of all-cause and sudden cardiac deaths after MI, but whether this is the case for VA after MI is unknown because the information on temporal trends in VA after MI is limited. Although several studies have reported a flat or declining incidence of VF after MI, similar data are not available for VT.
Thus, the present study was undertaken to examine the incidence of both VT and VF in a population-based cohort of persons with incident MI, the timing of occurrence of any VA after MI, variables associated with development of any VA after MI, the immediate and long-term effect on survival of VA after MI, and the temporal trends in incidence of any VA after MI.
Background: Although myocardial infarction (MI) severity is declining, the occurrence of ventricular arrhythmia (VA) after MI and its effect on outcome is unknown. This study was undertaken to examine the frequency and timing of VA and the effect of VA on mortality after MI.
Methods: Myocardial infarctions recorded between 1979 and 1998 were validated. Baseline characteristics, occurrence of VA, and survival were determined. Ventricular arrhythmias were categorized as primary ventricular fibrillation (VF), nonprimary VF, and ventricular tachycardia (VT). Logistic regression was used to analyze associations between VA and baseline characteristics. Temporal trends were assessed with the Mantel-Haenszel χ. Survival was analyzed with the Kaplan-Meier method. Proportional hazards regression was used to examine the association between death and occurrence of VA.
Results: Among 2317 persons with incident MI, 7.5% experienced VA (3.6% nonprimary VF, 2.1% primary VF, 1.8% VT). Ventricular arrhythmia–associated factors were younger age, female sex, higher Killip class, ST elevation, and atrial fibrillation. Ventricular arrhythmias were associated with increased risk of death at 30 days.
Conclusion: Ventricular arrhythmias after MI are relatively common, particularly among persons with more severe MI and no prior history of coronary disease. Over time, the incidence of VF declined, whereas VT did not change. Ventricular arrhythmia after MI was associated with a 6-fold increase in morality. Thus, identification of high-risk MI survivors and prevention of VA could markedly improve outcomes. Further studies are needed to determine the cause of the shift in distribution of VA subtype.
Ventricular arrhythmias (VAs), including ventricular tachycardia (VT) and ventricular fibrillation (VF), are life-threatening complications of acute myocardial infarction (MI). The reported incidence of VF varies from 2.1% to 12.4%, depending on the population and duration of observation, and that of VT ranges from 1% to 9.9%. The incidence of both VF and VT in the same population has been reported to be 1.9% to 10.2%; however, these data are the result of a small number of studies because most reports detail the incidence of VT or VF but not both.
Although the literature suggests most VAs after MI occur within 48 hours, data are limited by the small number of studies that report timing of VA. Older age and higher Killip class have been consistently associated with the development of VAs after MI, although other variables such as male sex, hypertension and hypotension, conduction disturbances, location of MI, and tobacco use have also been associated with development of VA but are reported in far fewer studies. In addition, because most studies examining VA after MI report on only VT or VF, the predictors of any VA after MI are less well defined.
Ventricular arrhythmias adversely affect inhospital survival. However, whether VAs also negatively affect long-term survival is unclear. Although several studies examining long-term outcomes report no increased risk in death beyond hospitalization for the index MI, others report an excess in mortality at 1 year, depending upon the arrhythmia subtype. The discrepancies may arise because these studies include patients selected for clinical trials, a limited number of VA subtypes, and limited follow-up. Importantly, these data primarily reflect the long-term effect of VF, whereas the long-term effect of VT remains unknown.
As therapeutic approaches to MI change and the severity of incident MI declines, a parallel decrease in complications after MI is expected. Indeed, some evidence indicates that rates of recurrent MI, heart failure, and death after MI are diminishing. Population studies have observed decreases in the number of all-cause and sudden cardiac deaths after MI, but whether this is the case for VA after MI is unknown because the information on temporal trends in VA after MI is limited. Although several studies have reported a flat or declining incidence of VF after MI, similar data are not available for VT.
Thus, the present study was undertaken to examine the incidence of both VT and VF in a population-based cohort of persons with incident MI, the timing of occurrence of any VA after MI, variables associated with development of any VA after MI, the immediate and long-term effect on survival of VA after MI, and the temporal trends in incidence of any VA after MI.
