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ECG signs of myocardial ischemia elicited by dipyridamole are frequent in patients with HCM and identify patients at higher risk of cardiac events, suggesting a potentially important pathogenetic role of inducible myocardial ischemia in determining adverse cardiac events in these patients.

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SUMMARY The value of a QRS scoring system derived from 12 lead electrocardiograms to estimate left ventricular ejection fraction was assessed in a prospective study of 285 hospital survivors of myocardial infarction. In these patients both the QRS score and ejection fraction were measured by radionuclide ventriculography at discharge. The correlation between ejection fraction and QRS score was weak. In 22 patients who died during six to 12 months follow up the ability of the ejection fraction and QRS score to predict mortality was assessed in terms of sensitivity, specificity, predictive value of a positive and negative test, and efficiency. For ejection fraction <40% and a QRS score >6 sensitivity was respectively 73% and 64%, specificity 73% and 56%, predictive value of a positive test 18% and 11%, predictive value of a negative test 97% and 95%, and efficiency 73% and 56%.Both ejection fraction and QRS score may be used to identify patients at low and high risk during one year follow up, but, contrary to initial expectations, the QRS score appears to be of little value in estimating ejection fraction and is less accurate than ejection fraction in predicting late survival in hospital survivors of myocardial infarction. For this group of 285 patients, the mean age was 57 (range 22-82) years, 82% were male, and 27% had a previous myocardial infarction. On admission 37% had an acute anterior myocardial infarction, 38% an inferior-posterior myocardial infarction, and 25% non-Q wave myocardial infarction; 74% were in Killip clinical class I. The median hospital stay was 13 (range 7-58) days.To determine the QRS score, standard 12 lead electrocardiograms were obtained on a three channel Hewlett Packard 1513 A automatic cardiograph recorder at a paper speed of 25 mm/s on the day of hospital discharge or one day before. Conventional speed and sensitivity were used, because they are advocated for current clinical use. The QRS scoring system as described by Wagner et a12 was applied (Table 1). The calculations were validated by the independent measurement of the score from a random sample of 39 electrocardiograms by the original author of the score, who was blinded to our measurements; the independent measurements showed no significant difference from the study readings (study score mean (SD) 4-8 (3.8) vs independent score 5.4 (3.9)). The

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