[Coronary vasomotor equivalents in the electrocardiographic behavior in induced ischemia]

In effort angina the exercise test can shift the ST-segment during the active phase and/or recovery. To investigate whether coronary vasomotility has some part in these electrocardiographic patterns, in 15 patients with stable effort angina we performed a quantitative angiographic evaluation of single, significant coronary stenoses (greater than 50%) during: spontaneous rhythm, graded atrial pacing (max 160 b/min) and at 1-3-5 min of recovery, both without drugs and after Ca-blockade (nifedipine, 10 mg sl). The greatest ST changes were at peak of the pacing in 9 patients (Group 1) and at recovery in 6 (Group 2). In each patient the stenotic lumen was reduced by atrial pacing (-9%, p less than 0.03); in Group 1 the lumen recovered soon after the end of the pacing, whereas in Group 2 narrowings became greater (-17%, p less than 0.02) at about 3 min of the recovery phase. In both groups nifedipine did not prevent the enhancement of the stenosis during pacing, but avoided constriction and ST changes during recovery in Group 2. Thus, in effort angina a superimposed active vasoconstriction contributes to the increase of the ST changes during the recovery phase of the exercise.