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In 285 patients who underwent selective coronary arteriography and atrial pacing for electrocardiographic diagnosis of suspected coronary failure, the sensitivity of this test was found to be rather poor: 43% positive results for atrial pacing compared to 50% for the submaximal exercise test, 75% for the maximal exercise test and 63% for the isoprenaline infusion test. In our experience atrial pacing is of diagnostic value only where uncertainty persists after a negative isoprenaline infusion test and an exercise test likewise negative but for some reason submaximal.

Previous investigations concerning isoproterenol infusion (PI) in the diagnosis of myocardial ischemia have shown that ischemic ECG changes are only significant if they persist or appear after discontinuing PI. In an effort to explain the mechanisms of this delayed response, hemodynamic parameters were measured in 10 patients with angiographically proven coronary disease before, during and after PI. It was found that the principal determinants of myocardial oxygen consumption (TTI and contractility) remain significantly elevated in the recuperation phase, but that aortic pressure and systemic arterial resistance, which diminish during PI, return to pre-infusion levels immediately after halting PI. The combined effects favor the late appearance of ischemic changes in the ECG. The coronary vasodilatation with resultant increased oxygen delivery to the myocardium seen during PI may be sufficient to meet the increased myocardial oxygen demand during PI but disappears immediately if PI is discontinued.

53 patients aged from 65 to 76 years underwent surgery for valvulopathies (23 patients), atherosclerotic heart disease (24 patients) or both diseases combined (6 patients). All these cases were in NYHA fonctional classes III and IV except for one patient in class II. Hospital mortality after surgical treatment of these cardiopathies was 3.8% (2 deaths). The late mortality of 19% (10 deaths), though high, was of non-cardiac origin in 7 of these patients. The clinical and hemodynamic findings in the two patients who died in the postoperative period were compared with those in the others. These two patients were more severely ill and had a greater degree of cardiomegaly than the average patient in the surviving group. The satisfactory clinical improvement in these elderly cardiac patients suggests that surgery can be recommended at least up to 75 years of age if there are no obvious contraindications. Life expectancy of 13-16 years for patients aged 65 and 8-9 years for patients aged 75 is a further reason for advocating surgical intervention.

In the patient suffering from angina, the protective effect of oxprenolol in the isoprenaline test is demonstrated by the reduction of disappearance of ischemic-type electrocardiographic alterations and of angina and rhythm disturbances. In our study, these results were obtained in spite of neutralization of the negative chronotropic effect of the beta-blocker through the use of an endo-auricular pacemaker. This points indirectly to the role played by the contractile state of the myocard in catecholamine-induced modifications of the oxygen intake of cardiac muscle.