Atrial Pacing During Percutaneous Transluminal Coronary Angioplasty: Results and Comparison with Exercise Treadmill Testing

Right atrial pacing (RAP) was used to immediately assess improvement in threshold for myocardial ischemia in 23 patients undergoing angiographically successful percutaneous transluminal coronary angioplasty (PTCA). Multiple coronary lesions were present in 19 patients, and 15 had incomplete revascular ization. All patients had RAP done immediately before and after completion of all dilatations, and in 13 patients pre- and post-PTCA exercise treadmill tests (ETT) were also performed. Angina occurred in 16 (70%) patients during pre- PTCA RAP, but in only 4 (17%) after PTCA (p < .05). The electrocardiogram was positive for ischemia (horizontal or downsloping ST depression ≥ 1 mm) in 18 patients (78%) during pre-PTCA RAP. However, 13 patients (57%) continued to have an ischemic response during post-PTCA RAP (not significant—NS). In 4 patients with multiple coronary lesions who had sequential pacing studies after PTCA of each lesion, the maximum degree of ST depression decreased by 1 mm or more after each dilatation in 3 patients but remained ≥ 1 mm in all. In the 13 patients undergoing both RAP and ETT, angina developed in 7 during pre- PTCA RAP and in 2 after PTCA (p < .05), compared with 8 and 3 (p < .05) during pre- and post-PTCA ETT, respectively. Ischemic ST depression occurred in 9 patients during pre-PTCA RAP and in 6 after PTCA (NS), and in 8 and 6 (NS) during pre- and post-PTCA ETT, respectively. Concordance between the two tests was good. The authors conclude that RAP can be used to document improvements in the threshold for ischemia as assessed by angina and, less consistently, by ST depression. However, use of RAP to guide PTCA of individ ual lesions is limited in patients with multiple coronary lesions (especially those undergoing incomplete revascularization), owing to difficulty in determining which lesion(s) are responsible for persistent ischemic ST depression (present in most patients with positive pre-PTCA tests) after PTCA. RAP does compare favorably with ETT for assessing post-PTCA ischemia and can be used as a substitute for exercise testing in patients unable to perform an adequate ETT.