Significance of Paroxysmal Atrial Fibrillation Complicating Acute Myocardial Infarction in the Thrombolytic Era

Abstract

Background-Paroxysmal atrial fibrillation (PAF) is considered a frequent complication of acute myocardial infarction (AMI), associated with increased in-hospital and long-term mortality rates. This notion is based on data collected before thrombolysis and additional modern methods of treatment became widely available, and no information is available on the significance of PAF in the general population with AMI in the thrombolytic era. The aim of the present study was to define the incidence, associated clinical parameters, and short-and long-term prognostic significance of PAF in patients with AMI in the thrombolytic era. Methods and Results-A prospective, nationwide survey was conducted of 2866 consecutive patients admitted with AMI in all 25 coronary care units in Israel during January/February 1992). The data were compared with a previous Israeli study of 5803 patients with AMI hospitalized in 1981 through 1983 (prethrombolytic era [PTE]). Patients in the TE with PAF were older and had a worse risk profile than those without PAF. PAF in the TE was independently associated with increased 30-day (odds ratio, 1.32; 95% confidence interval, 0.92 to 1.87) and 1-year (relative risk, 1.33; 95% confidence interval, 1.05 to 1.68) mortality rates. The incidence of PAF (8.9% and 9.9%) and the 30-day (25.1% and 27.6%) and 1-year (38.4% and 42.5%) mortality rates of patients with PAF were similar in the TE and PTE, although PAF in the TE occurred in older and sicker patients than those in the PTE. After adjustment for conventional risk factors, PAF was associated with significantly lower 30-day (odds ratio, 0.64; 95% confidence interval, 0.44 to 0.94) and 1-year (relative risk, 0.69; 95% confidence interval, 0.54 to 0.88) mortality rates compared with the PTE. Conclusions-Patients with AMI who develop PAF in the TE have significantly worse short-and long-term prognoses than patients without PAF, mostly due to their worse risk profile. After adjustment for confounding factors, patients with PAF in the TE have a better overall outcome than counterparts in the PTE, probably reflecting the better management of patients with AMI in the TE. (Circulation. 1998;97:965-970.)

Relationship of functional mitral regurgitation to new-onset atrial fibrillation in acute myocardial infarction

“…In accordance with previous studies,4 6 we noted that a worse Killip class and reduced left ventricular systolic function were independent predictors of AF, suggesting that elevated left atrial filling pressures are an important underlying mechanism in the development of AF. In addition, we observed a positive graded independent association between FMR severity and new-onset AF.…”

“…New-onset AF is a frequent arrhythmia complicating AMI1–4 6 15 and is associated with an adverse prognosis 2. The mechanisms that promote the development of AF in the AMI setting are complex and often multifactorial.…”

“…Experimental studies demonstrated that increased atrial stretch induced by increased atrial pressure shortens the atrial refractory period and greatly increases the vulnerability to AF 18. In clinical studies, AF is often associated with signs and symptoms of heart failure 2 4 6 19…”

“…Previous studies frequently did not adjust for the degree of left ventricular dysfunction1 4 6 and none considered the impact of FMR. FMR is a frequent complication of AMI and has been recognised as an important risk factor for mortality, adverse cardiac remodelling and the development of post-infarction heart failure and increased mortality 7 9 10.…”

Outcome of Patients in Relation to Duration of New-Onset Atrial Fibrillation following Acute Myocardial Infarction

“…Previous studies [1,10,11,12,13] have shown that AMI patients with AF had worse baseline characteristics, more complicated hospital course, and worse outcome than those without AF. In our earlier study [4], we found that overall AF was not an independent predictor of in-hospital and 7-year mortality.…”