Coronary artery bypass grafting versus stenting for unprotected left main coronary artery disease: where lies the body of proof?

Acute Coronary Syndrome With Unprotected Left Main Coronary Artery Culprit - An Observation From the AOI-LMCA Registry

BACKGROUND

Data on the clinical outcomes of percutaneous coronary intervention (PCI) for unprotected left main coronary artery (LMCA) in patients with acute coronary syndrome (ACS) are limited. Therefore, this study aimed to assess the clinical outcome of patients with ACS who underwent PCI for LMCA culprit lesion.Methods and Results:Of 1,809 patients enrolled in the Assessing Optimal Percutaneous Coronary Intervention for the LMCA (AOI-LMCA) registry (a retrospective 6-center registry of consecutive patients undergoing LMCA stenting in Japan), the current study population consisited of 1,500 patients with unprotected LMCA stenting for LMCA ACS (ACS with shock: 115 patients, ACS without shock: 281 patients) and stable CAD (1,104 patients). The cumulative 180-day incidence of death was markedly higher in the ACS with shock group than in the other groups (49.5%, 8.6%, and 3.3%, respectively; P<0.0001), but mortality beyond 180-day was not significantly different among the 3 groups (30.2%, 20.4%, and 19.5%, respectively; P=0.65). In the ACS with shock group, the initial TIMI flow grade did not affect 5-year mortality (57.1% and 62.2%, P=0.99), but in the ACS without shock group, 5-year mortality was significantly higher in patients with initial TIMI flow grade ≤1 than in patients with TIMI flow grade ≥2 (44.4% and 23.7%, respectively; P=0.008).

CONCLUSIONS

In patients with LMCA ACS, survival correlates with baseline hemodynamic and coronary flow status.

Shear Conditioning of Adipose Stem Cells for Reduced Platelet Binding to Engineered Vascular Grafts

Conferring antithrombogenicity to tissue-engineered vascular grafts remains a major challenge, especially for urgent bypass grafting that excludes approaches based on expanding autologous endothelial cells (ECs) that requires weeks of cell culture. Adipose-derived stem cells (ASCs) are available from most patients in sufficient number for coronary bypass graft seeding and may be effective as allogeneic cells. We thus compared the adhesion and platelet binding of human ASCs that were shear conditioned with constant and pulsatile shear stress (SS) after seeding the cells on a biologically engineered matrix suitable for arterial grafts. A monolayer of cells was maintained up to 15 dyn/cm² constant SS and up to 15 dyn/cm² mean pulsatile SS for 6 days of shear flow. Platelet binding was reduced from 83% to 6% of surface area and nitric oxide production was increased 23-fold with 7.5-15 dyn/cm² constant SS, but not pulsatile SS, relative to cells cultured statically on the matrix for 6 days. The reduction in platelet binding varied from no reduction to maximum reduction over a constant shear range of ∼2 to 4 dyn/cm², respectively. Collectively, the study supports the potential use of ASCs to seed the luminal surface of a vascular graft made from this biologically engineered matrix to confer an antithrombogenic surface during the development of an endothelium from the seeded cells or the surrounding blood and tissue.

Clinical outcome of unprotected left main coronary artery disease in patients with acute myocardial infarction

The clinical outcome of patients with acute myocardial infarction (MI) with unprotected left main coronary artery (LMCA) stenosis is not fully understood. We sought to assess the outcomes of patients with acute MI who underwent percutaneous coronary intervention (PCI) for unprotected LMCA stenosis. A total of 587 patients enrolled in the Korea Acute Myocardial Infarction Registry with LMCA stenosis were analyzed. Patients with culprit LMCA had higher inhospital mortality than patients with non-culprit LMCA (16.0% versus 8.9%, P = 0.008), but had similar clinical outcomes during a 12-month follow-up. Compared to CABG, PCI using drug-eluting stents (DES) was more frequently performed with similar early and 12-month clinical outcomes. The efficacy of sirolimus-eluting stents, paclitaxel-eluting stents, and zotarolimus-eluting stents were comparable at 12-month clinical follow-up. Predictors of 12-month mortality included mechanical ventilation, cardiogenic shock, age > 65 years, and ejection fraction < 40%. Patients with acute MI and culprit LMCA have higher early mortality than patients with non-culprit LMCA. PCI with DES is frequently performed and the clinical outcome is similar between the 3 types of first-generation DES.

Unprotected left main revascularization in patients with acute coronary syndromes

AIMS

In acute coronary syndromes (ACS), the optimal revascularization strategy for unprotected left main coronary disease (ULMCD) has been little studied. The objectives of the present study were to describe the practice of ULMCD revascularization in ACS patients and its evolution over an 8-year period, analyse the prognosis of this population and determine the effect of revascularization on outcome.

METHODS AND RESULTS

Of 43 018 patients enrolled in the Global Registry of Acute Coronary Events (GRACE) between 2000 and 2007, 1799 had significant ULMCD and underwent percutaneous coronary intervention (PCI) alone (n = 514), coronary artery bypass graft (CABG) alone (n = 612), or no revascularization (n = 673). Mortality was 7.7% in hospital and 14% at 6 months. Over the 8-year study, the GRACE risk score remained constant, but there was a steady shift to more PCI than CABG over time. Patients undergoing PCI presented more frequently with ST-segment elevation myocardial infarction (STEMI), after cardiac arrest, or in cardiogenic shock; 48% of PCI patients underwent revascularization on the day of admission vs. 5.1% in the CABG group. After adjustment, revascularization was associated with an early hazard of hospital death vs. no revascularization, significant for PCI (hazard ratio (HR) 2.60, 95% confidence interval (CI) 1.62-4.18) but not for CABG (1.26, 0.72-2.22). From discharge to 6 months, both PCI (HR 0.45, 95% CI 0.23-0.85) and CABG (0.11, 0.04-0.28) were significantly associated with improved survival in comparison with an initial strategy of no revascularization. Coronary artery bypass graft revascularization was associated with a five-fold increase in stroke compared with the other two groups.

CONCLUSION

Unprotected left main coronary disease in ACS is associated with high mortality, especially in patients with STEMI and/or haemodynamic or arrhythmic instability. Percutaneous coronary intervention is now the most common revascularization strategy and preferred in higher risk patients. Coronary artery bypass graft is often delayed and performed in lower risk patients, leading to good 6-month survival. The two approaches therefore appear complementary.