[Comparison between the treadmill exercise test and atrial stimulation with measurements of plasma catecholamines in patients with angina pectoris].

The assessment of atrial pacing (AP), in relation to the electrocardiographic treadmill test (ETT), was carried out in 22 patients with angina pectoris in whom the importance of the adrenergic system was also evaluated. Coronary cineangiography, left ventricular angiography and plasmatic catecholamine determinations were carried out before and after ETT and transvenous AP. All patients with coronary artery obstruction of more than 80% had positive ETT (X2 = 5.2) and 61.5% had positive AP tests (X2 = 5.2) and 61.5% had positive AP tests (X2 = 3.16). Sixty six of those patients without angiographic coronary obstruction had positive ETT and in 55.6% the AP test was also positive. The increase in systolic blood pressure was found to correlate with the increase in plasmatic catecholamine concentrations during ETT but not with AP (p less than 0.001). The electrocardiographic treadmill test has a greater specificity and sensitivity than AP and correlates with the plasmatic catecholamine concentration. Our results suggest that the myocardial ischemia produced by AP is not related to the endogenous output of catecholamines nor to the elevation of blood pressure, but rather it seems to be dependent of a greater imbalance between the cardiac debit supply ratio of oxygen induced exclusively by an increase in heart rate.