Efficacy of preconditioning with intracoronary diltiazem in preventing laser-induced spasm

Laser energy produces a multitude of effects, resulting both in therapeutic tissue ablation and complications such as laser-induced spasm (LIS). LIS can occur during lasing itself or during subsequent adjunctive angioplasty. Intracoronary diltiazem (ICD) can partially reverse LIS after it occurs. To determine whether pre-treatment with ICD might prevent LIS during laser interventions, 3 groups of 50 lesions each were studied. Group 1 served as controls receiving no ICD during the procedure. 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 but before adjunctive therapy. There were no differences in clinical characteristics of the 3 groups. Over 75% of lesions in each group were complex (B2 or C) lesions, and average lesion length was 15 mm in all 3 groups. Procedural success was > or = 94% in all groups. There was no significant difference among groups in pre-procedure artery stenosis, post-procedure stenosis, laser power used or number of laser pulses delivered. Pretreatment with ICD produced vasodilation 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% incidence of LIS. Group 2 had an 80% reduction of LIS during lasing (p < 0.01) but had increased LIS during adjunctive therapy with the same 12% incidence of LIS overall. Group 3 had only a 2% incidence of LIS (p < 0.01). We concluded that pretreatment with ICD significantly reduces LIS. Multiple infusions of ICD are necessary to sustain this protective effect.