Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 205

CABG is the only revascularization modality shown to improve survival in the high-risk subsets of stable CAD. In a meta-analysis that included the three classic trials of CABG vs. medical therapy, the Coronary Artery Surgery Study (CASS), the European Coronary Surgery Study (ECSS), and the VA study, CABG reduced mortality by 40–50% in the following groups:⁶⁸

 Left main disease (mortality reduction of ~75%).

 Three-vessel CAD, or one- or two-vessel CAD involving the proximal LAD. CABG is beneficial in these patients irrespective of LV function, but more so in the case of mild LV dysfunction with EF 35–50% or evidence of moderate/severe ischemia on stress testing (i.e., make sure CAD is functionally significant).

CABG was beneficial in the classic trials despite a 25% crossover to CABG in the medical therapy arm at 5 years, implying that the absolute CABG benefit is even higher. This CABG benefit was seen irrespective of symptom status and extended to asymptomatic patients. Note that the survival benefit in stable CAD does not emerge until 2 years after CABG, partly because of the early surgical hazard; thus, CABG is an appropriate therapy in patients who are otherwise likely to have a good longevity. CABG is expected to be beneficial sooner in patients with unstable CAD. Those trials were done in the 1970s, at a time when CABG technique was suboptimal (LIMA was not routinely used, which explains why the survival advantage of CABG gradually narrowed beyond 10 years). But in those trials medical therapy was also suboptimal (mainly consisting of β-blockers, with very limited use of aspirin and no statin). In fact, in the CABG stratum of the modern BARI 2D trial, initial CABG did not reduce the mortality of diabetic patients with multivessel, non-left main disease (vs. initial medical therapy). Same results were replicated in ISCHEMIA trial. Thus, the only absolute indication for CABG in the stable CAD setting is left main disease, not 3-vessel or proximal LAD disease.

The above trials excluded patients with severe LV dysfunction (EF <35%). In patients with severe ischemic LV dysfunction (EF <35%), no or mild angina, and no severe HF, CABG improved death and cardiovascular hospitalizations at 10 years in the STICH trial.^69,70The benefit was, however, not dramatic (~20% reduction of cardiovascular death). Once again, the benefit did not emerge until 2 years after CABG. This benefit was irrespective of viability testing.

CABG may also be performed for single- or two-vessel CAD not involving the LAD, if PCI is not technically feasible and the patient has refractory, severe angina. The value of a single- or two-vessel CABG to a non-LAD vessel is mainly symptomatic.

The well-known benefit of CABG in diabetic patients is seen in CABG vs. PCI trials, rather than in the above trials of CABG vs. medical therapy.