ABNORMAL CORONARY VASOCONSTRICTION AS A PREDICTOR OF RESTENOSIS AFTER SUCCESSFUL CORONARY ANGIOPLASTY IN PATIENTS WITH UNSTABLE ANGINA-PECTORIS

Background. High rates of restenosis after coronary angioplasty have been reported in patients with vasospastic angina. This study was designed to determine whether the occurrence of abnormal coronary vasoconstriction, detected by means of hyperventilation testing before angioplasty, influences the risk of restenosis after successful dilation. Methods. Hyperventilation testing was performed 0 to 4 days before coronary angioplasty in 106 consecutive patients with unstable angina and single-vessel coronary artery disease. Abnormal coronary vasoconstriction was considered present if hyperventilation-induced myocardial ischemia occurred during the recovery phase of the test. All patients had follow-up angiography 8 to 12 months after angioplasty. Results. Abnormal coronary vasoconstriction was observed in 48 patients (group 1), whereas 58 patients (group 2) had either a negative response throughout the test or a positive response only during the overbreathing phase of the hyperventilation test. Angioplasty was successful in 40 patients in group 1 and 51 in group 2. Restenosis was documented in 29 patients (73 percent) in group 1 and 13 (25 percent) in group 2 (relative risk of restenosis, 2.84; 95 percent confidence interval, 1.69 to 4.28; P < 0.001). In a multivariate analysis, the following three characteristics were independently related to the risk of restenosis (in descending order of importance): ST-segment elevation during spontaneous ischemic attacks (P < 0.001), hyperventilation-induced abnormal coronary vasoconstriction (P < 0.001), and the presence of a lesion more than 10 mm long in the left anterior descending coronary artery (P < 0.05). Conclusions. In patients with unstable angina and single-vessel coronary artery disease who have been selected for coronary angioplasty, the presence of hyperventilation-induced abnormal coronary vasoconstriction identifies a subgroup at high risk for restenosis.