Surgical treatment of left main coronary artery stenosis

Abstract: Clinical experience and follow-up of patients operated on with surgical arterial patch angioplasty of the left main coronary artery (LMCA) and observational retrospective studies in patients with LMCA obstruction who had undergone coronary artery bypass grafting (CABG) are reported. Patients: Forty-three patients were operated on with LMCA angioplasty during 1997 - 2003. Twelve patients were operated with an posterior approach and in 31 subsequent patients an aortic transsection technique was used. Additional bypass grafts were inserted in 21 patients (49%). Follow-up at a mean of 45 (range, 7 to 79) months included a stress test, echocardiography, and angiography with intravascular ultrasound of the LMCA. A total of 552 patients with documented LMCA obstruction had isolated primary CABG during 1970 - 1989. In 384 patients with an available angiography, feasibility of surgical angioplasty, severity of obstruction and survival were analyzed. In 496 patients the LMCA obstruction was obstructed classified as Iow- or high-grade or a completely occluded LMCA. Early (<30 days) and late mortality was analyzed in these three groups. Up to 1999 a total of 10647 patients underwent a first isolated CABG, of whom 1888 (18%) had significant LMCA stenosis. Early and late mortality was analyzed during a 30-year period in relation to gender and time of surgery. Results: In the angioplasty group there were three late deaths, none related to failure of the angioplasty. All patients had preserved left ventricular function. There was no aortic incompetence. All angioplasties investigated were patent without signs of restenosis or dilatation. The average dimensions of the LMCA after angioplasty were 4.8 mm and 5.6 mm, and in area 18.9 mm 2 and 24.8 MM2 in the distal and proximal parts, respectively. A bifurcation stenosis was the most frequent type of LMCA pathology present in 40%, followed by a circular stenosis in 25% and a mid-shaft stenosis in 24%. An ostial stenosis was found in 9%. Patients with an ostial stenosis were younger, tended to have less body weight, had less grafts inserted and were more frequently women than patients with other types of LMCA pathology. Risk of early death (odds ratio 2.6, 95% Confidence interval (Cl) 1.4-4.8) and mortality at ten years (relative risk 1.5, 95%CI 1. 1 - 2.0) was higher in patients with high-grade stenosis than in those without LMCA stenosis. The proportion of patients with LMCA stenosis of all CABG patients increased from 7% during the 1970s to 26% in 1999. During 1970-1984 early mortality was 5.8% in patients with LMCA stenosis compared to 1.5% in patients without (Odds Ratio (OR) 3.7 (95% CI 1.8 -7.6)). The corresponding rates during 1995-1999 were 2.0% versus 2.2% (OR 0.8 (95%CI 0.5-1.5)), respectively. Five-year mortality, exclusive of early deaths, during 19701984 was higher in patients with LMCA stenosis (12.8%) than in those without (8.4%) (Relative Risk 1.7 (95% CI 1.1 - 2.5)). The corresponding rates during 1995-1999 were 7% vs. 6,6% (OR 1,1 (95%CI 0,8-1,5)), respectively. There were gender differences observed so that an increased risk of early death in patients with LMCA stenosis was neutralised in males during 1985-1994 and in females during 1995-1999. An increased risk of late mortality in patients with LMCA stenosis was neutralised in males during 1985-94 and in females during 1995-99. Conclusions: The use of a proximal segment of the right internal mammary artery as an onlay patch for reconstructing LMCA is a safe and reproducible surgical technique and approximately 2% of all patients undergoing a first isolated CABG could be candidates for surgical angioplasty of the LMCA. Isolated ostial coronary stenosis is a separate clinical entity. High-grade LMCA stenosis is a risk factor for early and late death after CABG. The proportion of patients with LMCA stenosis of all CABG patients has increased since the 1970s. There was a decrease of early and late mortality in patients with LMCA stenosis after CABG despite increase of patient age and risk factors.