EFFICACY OF PRECONDITIONING WITH INTRACORONARY DILTIAZEM IN PREVENTING LASER-INDUCED SPASM

Laser energy produces a multitude of effects, resulting both in therap eutic tissue ablation and complications such as laser-induced spasm (L IS). LIS can occur during lasing itself or during subsequent adjunctiv e angioplasty. Intracoronary diltiazem (ICD) can partially reverse LIS after it occurs. To determine whether pre-treatment with ICD might pr event LIS during laser interventions, 3 groups of 50 lesions each were studied. Group 1 served as controls receiving no ICD during the proce dure. Group 2 received 2.5 mg ICD before lasing. Group 3 received ICD before lasing and then a second infusion of 2.5 mg ICD after lasing bu t before adjunctive therapy. There were no differences in clinical cha racteristics of the 3 groups. Over 75% of lesions in each group were c omplex (B2 or C) lesions, and average lesion length was 15 mm in all 3 groups. Procedural success was greater than or equal to 94% in all gr oups. There was no significant difference among groups in pre-procedur e artery stenosis, post-procedure stenosis, laser power used or number of laser pulses delivered. Pretreatment with ICD produced vasodilatat ion of the minimum lumen diameter from 0.86 +/- 0.1 to 1.0 +/- 0.1 mm (p<0.01) and was well tolerated. Control patients exhibited a 12% inci dence of LIS. Group 2 had an 80% reduction of LIS during lasing (p<0.0 1) but had increased LIS during adjunctive therapy with the same 12% i ncidence of LIS overall. Group 3 had only a 2% incidence of LIS (p<0.0 1). We concluded that pretreatment with ICD significantly reduces LIS. Multiple infusions of ICD are necessary to sustain this protective ef fect.