Impact of IVUS guidance on long-term mortality in stenting for unprotected LM stenosis
In a 2009 analysis of the large multicenter registry of the revascularization for unprotected LM stenosis: COMparison of Percutaneous coronary Angioplasty versus surgical Revascularization (MAIN-COMPARE) study, Park et al compared the long term outcomes of IVUS-guided and conventional angiographi c stent implantation in patients with LM lesions. 6 The analysis included 975 patients, of whom 756 (77.5%) underwent IVUS-guided stenting and 219 (22.5%) underwent angiog raphy-guided procedures. Since patient and procedural characteristics differed bet ween groups, propensity score matching, a statistical technique that selects 2 similar g roups of patients with the same baseline characteristics within a study population, created 201 matched pairs of patients.
At 3-year follow-up, 102 patients (51%) undergoing IV US guidance and 116 patients (58%) undergoing angiography guidance had dropped out of the study. However, an analysis of the remaining patients showed that the use o f IVUS guidance during stent implantation was associated with a 46% lower risk of 3-yea r mortality compared with angiography guidance (6.0% vs. 13.6%, log-rank p= 0.063; HR , 0.54; 95% CI, 0.28 to 1.03). When the analysis was limited to 145 matched pa irs of patients receiving drug- eluting stents (DES) , the risk reduction in 3-year mortality was more striking: 61% with IVUS guidance compared with angiography guidance (4.7% v ersus 16.0%, log-rank p= 0.048; HR , 0.39; 95% CI, 0.15 to 1.02). However , in 47 matched patients receiving bare metal stent (BMS), the use of IVUS guidance did not reduce the risk of 3-year mortality (8.6% versus 10.8%, log-rank p= 0.35; hazard ratio, 0.59; 95% CI, 0.18 to 1.91). IVUS guided stenting did not affect the incidence of m yocardial infarction or target vessel revascularization. The use of DES has been associated with higher rates of late stent thrombosis than with BMS. It is therefore possible that IVUS guidance reduces the stent thrombosis risk.
This was the first study to show a mortality benefit for IVUS-guided procedures in LM CAD, and provided evidence to justify future large r andomized studies. This study is particularly important because at the time of publica tion, stent implantation in patients with unprotected LM disease was a rapidly growing procedure but represent ed a major clinical challenge. The authors concluded that the study p rovided evidence to recommend the routine use of IVUS in stent implantati ons in LM stenosis.