Importance of the time of onset of supraventricular tachyarrhythmias on prognosis of patients with acute myocardial infarction

Short- and long-term prognosis of previous and new-onset atrial fibrillation in ST-segment elevation acute myocardial infarction

INTRODUCTION AND OBJECTIVES

The impact of atrial fibrillation on the prognosis of myocardial infarction is still the subject of debate. We analyzed the influence of previous and new-onset atrial fibrillation on in-hospital and long-term prognosis in patients with acute myocardial infarction.

METHODS

Prospective study of 4284 patients with ST-segment elevation acute myocardial infarction. We studied all-cause in-hospital and long-term mortality (median, 7.2 years) using adjusted models.

RESULTS

In total, 3.2% of patients had previous atrial fibrillation and 9.8% had new-onset atrial fibrillation. In general, both groups of patients had a high baseline risk profile and an increased likelihood of in-hospital complications. The crude in-hospital mortality rate was higher in patients with previous atrial fibrillation than in those with new-onset atrial fibrillation (22% vs 12%; P<.001; 30% vs 10%; P<.001). The long-term mortality rate was 11.11/100 patient-years in patients with previous atrial fibrillation and 5.35/100 patient years in those with new-onset atrial fibrillation (both groups, P<.001). New-onset fibrillation alone (odds ratio=1.55; 95% confidence interval, 1.08-2.22) was an independent predictor of in-hospital mortality. Previous atrial fibrillation (hazard ratio=1.24; 95% confidence interval, 0.94-1.64) and new-onset atrial fibrillation (hazard ratio=0.98; 95% confidence interval, 0.80-1.21) were not independent predictors of long-term mortality.

CONCLUSIONS

New-onset atrial fibrillation during hospitalization is an independent risk factor for in-hospital mortality in acute myocardial infarction.

Atrial fibrillation and death after myocardial infarction: a community study

BACKGROUND

Atrial fibrillation (AF) often coexists with myocardial infarction (MI), yet its prognostic influence is disputed. Prior reports studied the relationship of AF during early hospitalization for acute MI to the risk of death and could not address the timing of AF in relation to the MI (ie, before, during, after). Furthermore, as data come mostly from clinical trials, their applicability to the community is uncertain. The aims of our study were to assess the occurrence of AF among MI patients, determine whether it has changed over time, and quantify its impact and the impact of its timing on mortality after MI.

METHODS AND RESULTS

This was a community-based cohort of 3220 patients hospitalized with incident (first-ever) MI from 1983 to 2007 in Olmsted County, MN. Atrial fibrillation was identified by diagnostic codes and ECG. Outcomes were all-cause and cardiovascular death. Atrial fibrillation before MI was identified in 304 patients, and 729 developed AF after MI (218 [30%] within 2 days, 119 [16%] between 3 and 30 days, and 392 [54%] >30 days post-MI). The cumulative incidence of AF after MI at 5 years was 19% and did not change over the calendar year of MI (the incidence of AF was the same regardless of when the MI occurred). During a mean follow-up of 6.6 years, 1638 deaths occurred. AF was associated with an increased risk of death (hazard ratio [95% confidence interval] 3.77 [3.37 to 4.21]), independently of clinical characteristics at the time of MI and heart failure. This risk differed markedly according to the timing of AF, and was the greatest for AF occurring >30 days post MI (hazard ratio [95% confidence interval] 1.63 [1.37 to 1.93] for AF within 2 days, 1.81 [0.45 to 2.27] for AF between 3 and 30 days, and 2.58 [2.21 to 3.00] for AF >30 days post MI).

CONCLUSIONS

In the community, AF is frequent in the setting of MI. Atrial fibrillation carries an excess risk of death, which is the highest for AF developing >30 days after MI.

Effect of beta-blockers on the risk of atrial fibrillation in patients with acute myocardial infarction

INTRODUCTION

Oral beta-blockers improve the prognosis of patients with acute myocardial infarction, while atrial fibrillation worsens the prognosis of this population. The reduction of atrial fibrillation incidence in patients treated with beta-blockers could at least in part explain the benefits of this drug.

OBJECTIVE

To investigate the effect of beta-blockers on the incidence of atrial fibrillation in patients with acute myocardial infarction.

METHODS

We analyzed 1401 patients with acute myocardial infarction and evaluated the occurrence or absence of atrial fibrillation, the use of oral beta-blockers and mortality during the first 24 hours.

RESULTS

a) The use of beta-blockers was inversely correlated with the presence of atrial fibrillation (rho = 0.004; OR = 0.54). b) Correlations with mortality were as follows: 31.5% in patients with atrial fibrillation, 9.2% in those without atrial fibrillation (rho < 0.001; Odds Ratio = 4.52), and 17.5% in patients not treated with beta-blockers and 6.7% in those who received the drug (rho < 0.001; OR = 0.34). c) Adjusted Models: The presence of atrial fibrillation was independently correlated with mortality (OR = 2.48, rho = 0.002). The use of beta-blockers was inversely and independently correlated with mortality (OR = 0.53; rho = 0.002). The patients who used beta-blockers showed a lower risk of atrial fibrillation (OR = 0.59; rho = 0.029) in the adjusted model.

CONCLUSION

The presence of atrial fibrillation and the absence of oral beta-blockers increased in-hospital mortality in patients with acute myocardial infarction. Oral beta-blockers reduced the incidence of atrial fibrillation, which might be at least partially responsible for the drug's benefit.

Significance of recurrences of new atrial fibrillation in acute myocardial infarction

BACKGROUND

Although new-onset atrial fibrillation (AF) frequently recurs following the acute myocardial infarction, the significance of AF recurrences is unknown.

OBJECTIVE

The objective of the present study was to evaluate the incidence, clinical predictors and prognostic significance of AF recurrences following the acute myocardial infarction.

METHODS AND RESULTS

A total of 320 consecutive patients with AF following the acute myocardial infarction were evaluated and the patients with AF recurrences were compared to those with single episodes of AF in whom AF did not recur after restoration of sinus rhythm. The incidence of AF recurrences was 22.5%. AF recurrences were highly associated with congestive heart failure and worse Killip class was identified as the most important predictor of AF recurrences. Patients with AF recurrences had poorer outcome, including higher in-hospital (36.1% versus 12.9%) and 7-year (68.2% versus 48.6%) mortality. After multivariate adjustment, AF recurrence remained an independent predictor of in-hospital [odds ratio (OR) = 3.08, 95% confidence interval (CI), 1.45-6.53, p = 0.001], and 7-year [relative risk (RR) = 1.52, 95% CI, 1.00-2.31, p = 0.026] mortality.

CONCLUSION

New-onset AF frequently recurs following the acute myocardial infarction and our analysis demonstrated that recurrences of AF independently predicted in-hospital and long-term mortality.

Prognostic significance of new atrial fibrillation and its relation to heart failure following acute myocardial infarction

BACKGROUND

New-onset atrial fibrillation (AF) after acute myocardial infarction (AMI) frequently occurs in association with postinfarction complications, particularly with heart failure (HF).

AIMS

To evaluate whether postinfarction HF is associated with the subsequent development of AF and whether AF independently predicts poorer prognosis.

METHODS AND RESULTS

We examined 650 patients with AMI and compared patients with AF (n=320) to those without (n=330). AF patients were classified as either early AF (n=208)-patients who developed AF within 24 h of symptom onset or late AF (n=112)-patients who had AF thereafter. We compared outcomes between these groups, adjusting for differences in baseline characteristics and postinfarction HF. Heart failure was the most important predictor of AF. In most patients, AF occurred secondary to HF. AF patients had poorer outcomes, including higher in-hospital and 7-year mortality. After multivariate adjustment, overall, AF was not an independent predictor of in-hospital [odds ratio (OR)=0.70) and 7-year [relative risk (RR)=1.14] mortality, but late AF remained an independent predictor of 7-year (RR=2.48, 95% confidence interval, 1.26-4.87) mortality.

CONCLUSIONS

Heart failure mostly preceded the occurrence of new-onset atrial fibrillation after acute myocardial infarction, but only late atrial fibrillation was independently related to long-term mortality.

TACHYARRHYTHMIAS ASSOCIATED WITH ACUTE MYOCARDIAL INFARCTION

The occurrence of tachyarrhythmias in the setting of an MI is quite common. As appropriate therapy for the MI is underway, any tachyarrhythmia should be quickly recognized, the cause determined, and appropriate therapy initiated because of instability or before the onset of a cycle of ischemia, begetting tachycardia, begetting more ischemia.

Acute myocardial infarction complicated by atrial fibrillation in the elderly: prevalence and outcomes

BACKGROUND

Although atrial fibrillation (AF) is a common complication of acute myocardial infarction (MI), patient characteristics and association with outcomes remain poorly defined in the elderly.

METHODS AND RESULTS

We evaluated 106 780 Medicare beneficiaries > or =65 years of age from the Cooperative Cardiovascular Project treated for acute MI between January 1994 and February 1996 to determine the prevalence and prognostic significance of AF complicating acute MI in elderly patients. Patients were categorized on the basis of the presence of AF, and those with AF were further subdivided by time of AF (present on arrival versus developing during hospitalization). AF and non-AF patients were compared by univariate analysis, and logistic regression modeling was used to identify clinical predictors of AF. The influence of AF on outcomes was evaluated by unadjusted Kaplan-Meier survival curves and logistic regression models. AF was documented in 23 565 patients (22. 1%): 11 510 presented with AF and 12,055 developed AF during hospitalization. AF patients were older, had more advanced heart failure, and were more likely to have had a prior MI and undergone coronary revascularization. AF patients had poorer outcomes, including higher in-hospital (25.3% versus 16.0%), 30-day (29.3% versus 19.1%), and 1-year (48.3% versus 32.7%) mortality. AF remained an independent predictor of in-hospital (odds ratio [OR], 1. 21), 30-day (OR, 1.20), and 1-year (OR, 1.34) mortality after multivariate adjustment. Patients developing AF during hospitalization had a worse prognosis than patients who presented with AF.

CONCLUSIONS

AF is a common complication of acute MI in elderly patients and independently influences mortality, particularly when it develops during hospitalization.

[Incidence, clinical characteristics and prognostic significance of supraventricular tachyarrhythmias in acute myocardial infarction]

OBJECTIVES

The study of incidence and prognostic significance of supraventricular tachyarrhythmias in patients with acute myocardial infarction.

PATIENTS AND METHODS

Prospective study on 1,239 patients consecutively admitted because of a diagnosis of acute myocardial infarction. Clinical characteristics, indexes of myocardial infarction and complications were analysed.

RESULTS

Supraventricular tachyarrhythmias were observed in 116 (9.3%) cases: atrial fibrillation in 96 (7.7%); atrial tachycardia in 15 (1.2%); and atrial flutter in the remaining five cases (0.4%). Patients with supraventricular tachyarrhythmias were older, and presented higher heart rate, lower blood pressure, a higher number of affected leads in ECG, and higher Killip class. A higher creatine kinase peak and a lower left ventricular ejection fraction were associated with the presence of supraventricular tachyarrhythmias. Predictors of supraventricular tachyarrhythmias were: age, systolic blood pressure, number of affected leads in ECG, and congestive heart failure at admission. The following complications were found more frequently in patients with supraventricular tachyarrhythmias: bundle-branch block, complete A-V block, ventricular tachycardia, ventricular fibrillation; heart failure; stroke; and mortality, in-hospital 18.1% vs 11.1% (p < 0.05) and one-year, 38.7% vs 18.4% (p < 0.001). The logistic regression model showed that supraventricular tachyarrhythmias had no independent prognostic value on mortality.

CONCLUSIONS

The appearance of supraventricular tachyarrhythmias during the acute phase of myocardial infarction is a relatively frequent finding, often associated with older age and larger infarctions. Supraventricular tachyarrhythmias are accompanied by higher short and long-term mortalities, although there is no independent prognostic significance.

Atrial fibrillation in the setting of acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries

OBJECTIVES

We examined the clinical predictors and angiographic and clinical outcomes associated with atrial fibrillation in the setting of acute myocardial infarction (MI).

BACKGROUND

This condition has been studied primarily in prethrombolytic era small trials.

METHODS

We compared baseline clinical characteristics, short-term clinical and angiographic outcomes and 1-year mortality of patients enrolled in the Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO-I) trial with atrial fibrillation on admission electrocardiography (n = 1,026 [2.5%]) or after enrollment (n = 3,254 [7.9%]) and those without atrial fibrillation (n = 36,611 [89.6%]). Univariable and multivariable analyses were used to assess relations between baseline factors and the development of atrial fibrillation.

RESULTS

Patients with any atrial fibrillation more often had three-vessel coronary artery disease and initial Thrombolysis in Myocardial Infarction (TIMI) grade < 3 flow than those without the arrhythmia. In-hospital stroke was increased in patients with atrial fibrillation (3.1% vs. 1.3%, p = 0.0001), mainly ischemic stroke (1.8% vs. 0.5%, p = 0.0001). Significant multivariable predictors of later atrial fibrillation included advanced age, higher peak creatine kinase levels, worse Killip class and increased heart rate. The unadjusted mortality rate was significantly higher at 30 days (14.3% vs. 6.2%, p = 0.0001) and at 1 year (21.5% vs. 8.6%, p < 0.0001) in patients with atrial fibrillation. The adjusted 30-day mortality rate remained significantly higher with any (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.2 to 1.4) or later (OR 1.4, 95% CI 1.3 to 1.5) atrial fibrillation but not with baseline atrial fibrillation (OR 1.1, 95% CI 0.88 to 1.3).

CONCLUSIONS

Atrial fibrillation in the setting of acute MI independently predicts stroke and 30-day mortality. More aggressive treatment strategies in this subgroup may be warranted and deserve further study.