Can single-lead computerized electrocardiography predict myocardial infarction in young and middle-aged men? The Tromsø study.
BACKGROUND
In epidemiological studies, the electrocardiogram has often been interpreted by means of a categorical classification. Computerized recording offers the possibility of analysing electrocardiographic measurements as continuous variables.


OBJECTIVE
To test the hypothesis that duration of QRS complex and T-wave inversion would be independent predictors of myocardial infarction.


METHODS
In a population-based study, we prospectively investigated the risk of developing myocardial infarction according to duration of ORS complex and peak-to-peak T-wave amplitude measured from lead I of the 12-lead electrocardiogram by computerized electrocardiography. In total 6628 men aged 25-61 years who had not previously suffered a myocardial infarction were followed up for 3.9 years.


RESULTS
Eighty-two first myocardial infarctions (55 non-fatal and 24 fatal myocardial infarctions and three sudden deaths) were identified. The risk of myocardial infarction increased with duration of ORS complex and with decreasing T-wave amplitude. A proportional hazards model with adjustment for possible confounders yielded a relative risk of myocardial infarction of 3.74 (P for linear trend 0.015) for duration of QRS complex > or = 120 ms compared with duration of QRS complex <80 ms. The multivariate relative risk for T-wave amplitude > or = 0.35 mV compared with T-wave amplitude < 0.20 mV was 0.55 (P for linear trend 0.036). When both duration of ORS complex and T-wave amplitude were included in the multivariate model, T-wave amplitude retained its predictive power, whereas duration of ORS complex became marginally no longer significant (P=0.067).


CONCLUSIONS
Peak-to-peak T-wave amplitude from lead I is an independent predictor of myocardial infarction in men who have not previously suffered a myocardial infarction. Greater duration of ORS complex clearly indicates a higher risk of myocardial infarction. However, when T-wave amplitude is included as a covariate, the predictive power of duration of QRS complex does not remain significant. Single-lead electrocardiography is a feasible method for improving the assessment of the relative risk of myocardial infarction.
Løchen
M L
ML
Institute of Community Medicine, University of Tromsø, Norway. majalisa@ism.uit.no
Rasmussen
K
K
Macfarlane
P W
PW
Arnesen
E
E
D000328:Adult; D004562:Electrocardiography / Q000379:methods*; D001330:Electronic Data Processing; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D009664:Norway / Q000453:epidemiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires