Korean Registry Shows PCI Increasingly Used for Left Main Disease, With Improving Outcomes
Both the use and safety of PCI for unprotected left main stenosis have increased significantly in recent years, according to results of a registry study published in the March 2015 issue of Circulation: Cardiovascular Interventions.
Researchers led by Seung-Jung Park, MD, PhD, of Asan Medical Center (Seoul, South Korea), examined temporal revascularization trends from 1995 to 2010 in 2,618 consecutive patients who underwent elective PCI (n = 1,124) or CABG (n = 1,494) and were enrolled in the ASAN Medical Center-Left Main Revascularization (ASAN MAIN) registry. The analysis looked at 3 distinct time eras:
- BMS (1995-1998)
- Early DES (2003-2006)
- Late DES (2007-2010)
Mean patient age in both treatment groups increased over the study period (P < .001). Additionally, by the late DES era, more patients had comorbidities such as hypertension, diabetes, hyperlipidemia, and history of stroke. Other observed changes were increases over time in the extent and complexity of unprotected left main stenosis and a decrease in mean ejection fraction.
Prevalence of PCI use increased from 34.6% in the BMS era to 51.8% in the late DES era. At the same time, there was an increase in IVUS employed during PCI from 79.9% to 86.6%, respectively. In terms of stent technique, the percentage of devices primarily implanted in left main ostial or shaft lesions declined from 65% to 14.5% across time periods. In the late DES era, bifurcation lesions were more frequently treated with a single-stent crossover technique than with a 2-stent technique (60.3% vs 25.1%; P < .001).
Patients undergoing surgery also saw changes, most notably a large and steady increase in off-pump CABG from 14.8% to 66.8% (P < .001). While the total number of grafts per surgery decreased, use of the left internal mammary artery grew from 86.4% to 96.6% (P < .001).
In the PCI cohort, the incidence of risk-adjusted MACCE (primary endpoint; death, MI, stroke, or repeat revascularization) decreased from 20.18 to 6.77 cases per 100 person-years across eras (P < .001 for trend). Risks of death, the composite of death, MI, or stroke, and repeat revascularization also fell (table 1).
In the CABG cohort, outcomes held steady apart from a reduction in the risk of repeat revascularization (adjusted HR 0.60; 95% CI 0.38-0.95). CABG carried a lower risk of MACCE compared with PCI for the first 2 eras, although the gap narrowed and eventually disappeared by the late DES era; the shift was due to improving PCI outcomes and unchanging CABG outcomes.
According to Dr. Park and colleagues, possible explanations for the PCI trends are:
- Introduction of DES
- Development and widespread use of second-generation DES
- Progressive increase in the use of IVUS during PCI
- Simplification of stenting techniques
- Optimization of antiplatelet and adjuvant pharmacological treatment
But, the researchers say, the lack of decline in clinical events in the CABG group is harder to explain. “Therefore, these findings should be considered as … hypothesis generating and should be confirmed in [a] large randomized controlled study,” they conclude.
It’s Not All About the Stent
Davide Capodanno, MD, PhD, of Ferrarotto Hospital (Catania, Italy), expressed surprise that there was no improvement in CABG outcomes. He told TCTMD in an email that the results “are interesting in that the decrease in mortality observed across waves in the PCI group is paralleled by an increase in left main complexity.”
But it is unlikely that the transition to second-generation DES played a major role in the mortality reduction observed in the PCI group, he suggested. In his own meta-analysis of everolimus-eluting stents vs first-generation DES in patients with left main disease, the pooled HR for mortality with second- vs first-generation DES was 1.04. Instead, he said, the larger contribution to better survival likely came from “the growing experience of the center and extensive application of what they have learned from IVUS since [the BMS era].”
Similarly, Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), notes in an accompanying editorial that “the improved outcomes with PCI relative to CABG observed over time in this study cannot simply be ascribed to differences in stent type.”
A Role for Comparative Effectiveness
According to Dr. Stone, the results “are provocative, and prompt discussion as to whether PCI with contemporary DES and the adjunctive drugs, devices, and techniques used in the recent period should now be considered standard of care (class I) for many patients with [unprotected left main] disease.” Additionally, he says the study “challenges the relevance of randomized trials, such as SYNTAX, to today’s practice.”
Dr. Stone notes that while “adequately powered, meticulously conducted RCTs are typically required to change practice,” comparative effectiveness studies can complement “by documenting changes in practice patterns and overall outcomes, as well as identifying low frequency safety issues.”
Looking to EXCEL
In the meantime, 2 RCTs of PCI vs CABG in this population are underway (EXCEL and NOBLE) and results for both are expected in the fall of 2016, according to Dr. Stone. If these trials are positive, they would pave the way for PCI to achieve class I status for treatment of unprotected left main disease.
“Moreover, with the EXCEL and NOBLE results in hand, it will be fascinating to revisit the [ASAN MAIN] registry to reexamine the similarities and differences between reality and the real world,” Dr. Stone says.
Dr. Capodanno agreed that the EXCEL trial—which recommends but does not mandate the use of IVUS and FFR guidance—“will tell us if the introduction of these procedural and strategic items also translates into lower mortality rates compared with those observed in the SYNTAX trial.”
1. Park S-J, Ahn J-M, Kim Y-H, et al. Temporal trends in revascularization strategy and outcomes in left main coronary artery stenosis: data from the Asan Medical Center-Left Main Revascularization registry. Circ Cardiovasc Interv. 2015;Epub ahead of print.
2. Stone GW. Left main revascularization: reality versus the real world [editorial]. Circ Cardiovasc Interv. 2015;Epub ahead of print.
- The study was supported by funds from the CardioVascular Research Foundation, Seoul, South Korea, and the Health 21 R&D Project, Ministry of Health and Welfare, South Korea.
- Dr. Park reports no relevant conflicts of interest.
- Dr. Stone reports being a past consultant for Boston Scientific.
- Dr. Capodanno reports receiving speaker’s bureau and advisory board fees from AstraZeneca, Eli Lilly, and The Medicines Company.