ASCERT: Long-term Survival Appears to Favor CABG Over PCI for Multivessel Disease

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Among ‘real world’ patients with multivessel disease, percutaneous coronary intervention (PCI) improves survival compared with coronary artery bypass grafting (CABG) up to 1 year after the procedure. But over the long term, surgery shows a progressively higher survival advantage, according to preliminary results of a large observational study.

The analysis, focusing on anatomically high-risk subsets, was presented ahead of the primary results, which are scheduled to be released this March at the American College of Cardiology (ACC) Scientific Sessions in Chicago, IL. The preliminary report was presented January 30, 2012, at the annual meeting of the Society of Thoracic Surgeons (STS) in Fort Lauderdale, FL.

For the ASCERT (ACCF-STS Database Collaboration on the Comparative Effectiveness of Revascularization Strategies) study, investigators led by Fred H. Edwards, MD, of the University of Florida, Jacksonville (Jacksonville, FL), analyzed outcomes for patients with 2- or 3-vessel disease who underwent CABG (n = 86,244) or PCI (n = 103,549) from 2004 through 2007.

The CABG population was taken from the STS National Database and the PCI population from the ACC National Cardiovascular Data Registry. To obtain long-term follow-up, patient records were linked to administrative data from the Centers for Medicare and Medicaid Services. Propensity scores and inverse probability weighting were used and numerous clinical subgroups were prespecified.

CABG Survival Advantage Persists Over Time

In all subgroups, survival in the first year favored PCI. However, after 1 year, all subgroups showed a progressively increasing survival advantage for CABG. Additionally, when the spectrum of propensity scores was divided into quintiles of CABG and PCI patients with similar clinical characteristics, a CABG survival advantage persisted across each quintile (RR for mortality at 4 years, range 0.75-0.82).

At 4 years there was a 22% risk reduction in adjusted mortality in the CABG group compared with the PCI group (RR 0.78; 95% CI 0.74-0.82). A similar pattern was observed regardless of age, gender, diabetes status, and ejection fraction.

Importantly, the high-risk subgroup, which included patients age 75 or older who were diabetic, had an ejection fraction less than 50% and had an eGFR less than 60 mL/min/1.73 m², demonstrated a CABG survival advantage similar to the low-risk group (table 1).

Table. Four-Year Survival

The survival advantage for CABG also was seen in each individual subgroup at 4 years (table 2).

Table 2. Four-Year Survival: Subgroups

 
“The focus of the ASCERT study was on ‘real world’ patients,” Dr. Edwards said in a press release. “Previous observational studies have shown a long-term survival advantage for CABG over PCI. These partial ASCERT results confirm that in important high-risk clinical subsets, the CABG survival advantage can also be seen in a large nationwide population.”

Unbalanced and Misinterpreted

But Christopher J. White, MD, of the Ochsner Heart and Vascular Institute (New Orleans, LA), disagreed, saying the study does not represent an all-comers population. Rather, the data are only confirmatory in selected patients.

“What ASCERT really says is that in a nonrandomized database, we are actually doing a pretty good job of choosing patients who need surgery,” he said in a telephone interview with TCTMD. “There was a 22% reduction in mortality in patients who underwent surgery because the cardiologists knew who to send to surgery.”

Dr. White added that since many very sick patients who are turned down for CABG end up undergoing PCI, the higher mortality in the PCI group makes sense.

“The important thing here is that the PCI and CABG groups are not the same, so you can’t say that ASCERT in any way suggests surgery is a better treatment than angioplasty,” he said. “What it says is that if you are a patient [with comorbidities] and your physician follows current guidelines, you are going to get a pretty good outcome. In my opinion, [this study is confirming] that we are getting it right, using data from SYNTAX and other large trials to inform our decision making.”

Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), also expressed caution in interpreting the results. “Physicians, hospitals, payors and other parties must be very careful when considering the results from any observational study,” he told TCTMD in an e-mail communication. “These databases didn’t collect the in-depth reasons why patients were referred to PCI vs. CABG, and there are no doubt numerous unmeasured confounders that have not been (and cannot be) controlled for, despite the most sophisticated propensity adjusted analyses. For this reason, all such studies must be considered exploratory, and not accepted until confirmed (or refuted) in randomized trials. For example, most large registries of drug-eluting stents vs. bare metal stents showed impressive reductions in mortality for drug-eluting stents. In contrast, all of the large DES/BMS randomized trials showed nearly identical mortality. Caveat emptor.”

 

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Source:
Edwards FH. Survival analysis of clinical subsets from the ASCERT study (ACCF-STS Database Collaboration on the Comparative Effectiveness of Revascularization Strategies): CABG compared to percutaneous stent placement in 189,793 patients with multivessel coronary disease. Presented at: Society of Thoracic Surgeons 48^th Annual Meeting; January 30, 2012; Fort Lauderdale, FL.

 

 

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