Prediction of sudden cardiac death after myocardial infarction in the beta-blocking era.
OBJECTIVE
This study assessed the predictive power of arrhythmia risk markers after an acute myocardial infarction (AMI).


BACKGROUND
Several risk variables have been suggested to predict the occurrence of sudden cardiac death (SCD), but the utility of these variables has not been well established among patients using medical therapy according to contemporary guidelines.


METHODS
A consecutive series of 700 patients with AMI was studied. The end points were total mortality, SCD, and nonsudden cardiac death (non-SCD). Nonsustained ventricular tachycardia (nsVT), ejection fraction (EF), heart rate variability, baroreflex sensitivity, signal-averaged electrocardiogram (SAECG), QT dispersion, and QRS duration were analyzed (n = 675). Beta-blocking therapy was used by 97% of the patients at discharge and by 95% at one and two years after AMI.


RESULTS
During a mean (+/-SD) follow-up of 43 +/- 15 months, 37 non-SCDs (5.5%) and 22 SCDs (3.2%) occurred. All arrhythmia risk variables differed between the survivors and those with non-SCD (e.g., the standard deviation of N-N intervals was 98 +/- 32 vs. 74 +/- 21 ms [p < 0.001] and the QRS duration was 103 +/- 22 vs.89 +/- 16 ms [p < 0.001]). Sudden cardiac death was weakly predicted only by reduced EF (<0.40; p < 0.05), nsVT (p < 0.05), and abnormal SAECG (p < 0.05), but not by autonomic markers or standard ECG variables. The positive predictive accuracy of EF, nsVT, and abnormal SAECG as predictors of SCD was relatively low (8%, 12%, and 13%, respectively).


CONCLUSIONS
The common arrhythmia risk variables, particularly the autonomic and standard ECG markers, have limited predictive power in identifying patients at risk of SCD after AMI in the beta-blocking era.
Huikuri
Heikki V
HV
Division of Cardiology, Department of Medicine, University of Oulu, Oulu, Finland. heikki.huikuri@oulu.fi
Tapanainen
Jari M
JM
Lindgren
Kai
K
Raatikainen
Pekka
P
Mäkikallio
Timo H
TH
Juhani Airaksinen
K E
KE
Myerburg
Robert J
RJ
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology*; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000188:drug therapy / Q000401:mortality; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012306:Risk
D000319:Adrenergic beta-Antagonists