[The diagnosis of perioperative myocardial infarction in heart surgery]. / El diagnóstico del infarto del miocardio perioperatorio en la cirugía del corazón.

Fifty three consecutive patients undergoing open heart surgery were prospectively studied to assess current techniques for diagnosing perioperative myocardial infarction (PMI). All patients had preoperative and postoperative electrocardiograms, serial determinations of serum creatine phosphokinase (CK), myocardial fraction of CK (CK-MB) and scintigraphy with technetium-99m labeled pyrophosphate. Seven patients (13.2%) sustained perioperative myocardial infarction. Four of these patients exhibited abnormal Q waves, and one poor R wave progression. Three of them had a positive scintigram. Two patients with a non-Q-wave infarction had a abnormal radioisotopic imaging. The CK and CK-MB were higher in patients with infarction (818.1 U) than in those without this complication (349 U) p less than 0.05. The relative sensitivity and relative specificity of given variables in the diagnosis of PMI were as follows: electrocardiogram 71.4% and 97.5% respectively; scintigraphy 71.4% and 94.1%; and serum enzymes 100% and 71.8%. Age, incidence of prior myocardial infarction, unstable angina, elevated left ventricular filling pressure, number of diseased coronary arteries, and number of grafts per patient did not correlate with PMI. Duration of extracorporeal circulation and number of electric shocks during surgery were slightly higher in the infarction group, but the difference was not significant. These results indicate that the combination of these three diagnostic procedures is the best way to evaluate myocardial damage after open heart surgery.

[Value of the exercise test in asymptomatic myocardial ischemia]. / El valor de la prueba de esfuerzo en la isquemia miocárdica asintomática.

To evaluate the predictive value of ischemic ST segment depression without associated chest pain during exercise testing, data were analyzed from 7305 studies. Two hundred thirty six patients were included in this study and were separated in 2 groups. Group A consisted of 169 patients without chest pain who, during exercise testing, showed a positive ST segment response (at least 1.5 mm of horizontal or downward ST segment depression for at least 0.08 second, compared with the resting baseline value), and Group B consisted of 67 patients who had both chest pain and a positive ST segment response. Selective coronary angiogram was performed on all patients. Each Group was separated into 3 sub-group according to the Cohn criteria: sub-group I (asymptomatic persons 8.3 vs 19.4%); sub-group II (patients with history of Myocardial Infarction 36.7% vs 19.4%); sub-group III (patients with chronic angina 55% vs 61.2%). The clinical characteristics, coronary risk factors, distribution of coronary artery disease, and exercise test response were similar in both groups. During treadmill exercise, the mean heart rate was 140.6 +/- 22 in group A versus 127.1 +/- 23 in the group B. The pressure-rate product was 2.4 +/- 0.8 versus 1.9 +/- 0.5, respectively (P less than or equal to 0.05). The predictive value for severe coronary artery disease of an exercise test in patients with asymptomatic ischemia was 77.5% as compared with 89.6% in the group with angina. This study confirms the high frequency of asymptomatic myocardial ischemia during exercise testing, compared with patients who had angina during exercise testing, with high percentage of prediction (77.5%) for coronary artery disease.