849 consecutive AMI were prospectively analyzed by continuous ECG monitoring (CEM) <48 hours after admission. Silent AF was defined as asymptomatic episodes lasting >30 sec. Symptomatic AF was defined as any AF occurring on ECG during the hospital stay, resulting in clinical symptoms or need for urgent cardioversion. The population was studied into three groups: No AF, Silent AF, and symptomatic AF. CHA2DS2VASc and GRACE risk score were calculated for risk assessment.
One hundred and thirty five patients (16%) developed silent AF and 45(5%) had symptomatic AF. Compared with the no AF group, patients with silent AF were markedly older 80 (67-85) vs. 62 (53-75) years; p<0.001), more frequently women (58 (43%) vs. 198 (30%); p=0.006), and less smoker (26 (20%) vs. 242 (36%); with p<0.001). Patients with silent and symptomatic AF, had higher CHA2DS2VASc score than patients without AF (5[4-6] and 5[4-6] vs 3[2-4], p<0.001).
CHA2DS2VASc score was similar in patients with silent and symptomatic AF (p=0.550). Mortality was higher in silent AF and symptomatic AF than in patients without AF ((14 (10.4%) and 8 (17.8%) vs 9 (1.3%)), p<0.001). CHA2DS2VASc score was associated with mortality in patients with AF, but not in patients without AF (OR[95% CI]: 1.32[1.02-1.72], p=0.036 and 1.22[0.88-1.71], p=0.236, respectively).
In the whole population, optimal threshold for predicting death for GRACE and CHA2DS2VASc risk scores were obtained by Receiver Operating Characteristic (ROC) curve (i.e. 153 and 4, respectively).
High CHA2DS2VASc (≥4) and GRACE (≥153) scores independently stratified mortality. By multivariate analysis, high CHA2DS2VASc score was an independent explanatory variable for death after AMI (OR[95% CI): 3.89[1.08-13.93]; p=0.037), beyond GRACE risk score (OR[95% CI]: 9.77[2.74-34.80]; p<0.001).
Patients with silent AF have level of CHA2DS2VASc risk similar to patients with symptomatic AF. A high CHA2DS2VASc score is associated with mortality, even when adjusted for GRACE risk score. These data suggest that CHA2DS2VASc score could improve risk stratification after AMI.