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In patients with multivessel disease who underwent percutaneous coronary intervention (PCI) during the era of first-generation drug-eluting stents (DES), incomplete revascularization heightened the risk of mortality at 5 years, according to a study published online June 4, 2013, ahead of print in the American Journal of Cardiology.

Edward L. Hannan, PhD, of the University at Albany, State University of New York (Albany, NY), and colleagues conducted a database analysis using the Percutaneous Coronary Intervention Reporting System of New York State and the Cardiac Surgery Reporting System to identify 21,767 patients with multivessel disease who underwent stenting from October 2003 to December 2005. The investigators also used the National Center for Health Statistics National Death Index to track all-cause mortality over a median of 3.9 years.

Complete revascularization was defined as achieving postprocedural stenosis of less than 50% in all lesions having preprocedural stenosis of at least 70% in major epicardial coronary vessels. The goal could be reached during index hospitalization or within 30 days using staged PCI procedures.

Incomplete Revascularization Risky, No Matter the Extent

Overall, 84.4% of patients received DES, and 8.3% received BMS. Complete revascularization occurred in 31.4% of patients, while the remaining 68.6% were incompletely revascularized. The prevalence of incomplete revascularization varied across hospitals and operators.

In a propensity-matched analysis of 6,511 pairs, patients with incomplete revascularization had a 16% greater risk of death than those with complete revascularization. Subgroup analyses of matched pairs with complete revascularization vs. incomplete revascularization in 1 vessel (n = 5,413) or multiple vessels (n = 1,098) also showed an association with mortality (table 1).

Table 1. Mortality Risk: Degree of Incomplete vs. Complete Revascularization

Five-year survival rates for patients with 1-vessel incomplete revascularization and their matched counterparts were 79.8% and 81.4%, respectively (P = 0.03). For multivessel incomplete vs. complete revascularization, the rates were 77% and 81%, respectively (P = 0.04).

Additional subgroup analyses found no evidence that the association between incomplete revascularization and long-term mortality was dependent on risk factors such as age, ejection fraction, previous MI, congestive heart failure, diabetes, proximal LAD stenosis of 70% or more, total coronary occlusion, renal failure, or New York State PCI risk score for in-hospital mortality of 8 or more versus less than 8.

Sensitivity analysis of DES patients (n = 5,687) found that those with incomplete revascularization had lower 5-year survival rates than those with complete revascularization (78.7% vs. 80.9%; P < 0.001) as well as increased mortality risk (HR 1.20; 95% CI 1.09-1.33; P < 0.001). Patients receiving DES were also at higher risk of death whether revascularization was incomplete in 1 vessel (HR 1.16; 95% CI 1.04-1.29; P = 0.008) or multiple vessels (HR 1.43; 95% CI, 1.12-1.81; P = 0.004).

Study of First-Generation DES Still Relevant

In an e-mail communication with TCTMD, Dr. Hannan wrote that the study was warranted "because there are still a high percentage of patients for whom first-generation DES are used." Additionally, from a practical standpoint, "we examined long-term outcomes that are not yet available for second-generation DES," he said.

Jeffrey W. Moses, MD, of Columbia University Medical Center/Weill Cornell Medical Center (New York, NY), agreed in a telephone interview that researchers do not yet have enough data to make determinations about second-generation DES in this context. "Researchers are exploring what data they have," he told TCTMD, adding that the follow-up in this paper is relatively robust.

Most prior studies evaluating PCI with first-generation DES, incomplete revascularization, and outcomes have been limited to 1 to 3 years follow-up, while Hannan et al followed patients for 5 years, added Harold L. Dauerman, MD, of the University of Vermont (Burlington, VT), in an e-mail communication with TCTMD.

Causative Relationship Questionable

According to Dr. Hannan, the lower survival seen with incomplete revascularization stems from the fact that patients whose vessels are not revascularized run the risk of MI and death.

Whether the relationship is truly causative is impossible to discern from an observational study, he said. However, "many measures were taken to minimize selection bias as much as possible, and many other studies have reached the same conclusion as our study."

Dr. Dauerman confirmed that incompletely revascularized patients generally have different baseline clinical and angiographic variables than those with complete revascularization. Some variables such as vessel size and lesion length are not captured in the New York State registry, he said. Despite efforts to control for baseline differences, "the lack of angiographically complete data limits the strength of the conclusions," he said.

However, Dr. Moses reported, the literature for DES, BMS, and balloon angioplasty all point to an association between incomplete revascularization and increased mortality, though he acknowledged that a number of confounders could be impacting study outcomes. Notably, Hannan et al evaluated all-cause mortality but not cardiac mortality, he said.

"The big question is," Dr. Moses stressed, "is incomplete revascularization a marker for more advanced disease?" Amelioration of ischemia may allow patients to live longer for a variety of reasons, whether by improving ventricular function or increasing tolerance for future events, he added. "There’s a lot of emerging data that residual ischemia is an adverse marker, and the objective should be to minimize the ischemia."

Clinical Practice Amid a Shifting Landscape

Dr. Hannan emphasized the fact that, in New York State, the incomplete revascularization rate runs at about 70%.

"When the general clinical practice is thought to be associated with increased risk of mortality, there is a challenge to clinicians that warrants attention," said Dr. Dauerman. Going forward, a better understanding of what would constitute a reasonable degree of incomplete revascularization—for example, leaving small territories, small vessels, and nonviable areas alone—may provide practitioners with more useful information, he commented.

As to how second-generation DES might change results, Dr. Hannan said that while the devices should reduce stent thrombosis rates compared to first-generation DES, the increase in MI and mortality seen with incomplete revascularization would remain the same.

Drs. Moses and Dauerman concurred, with the latter noting that "clinical impact of non-revascularized territories should be independent of DES type or generation."

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