Leaving Significant Stenoses Untreated After PCI May Worsen 1-Year Outcomes: SCAAR Data

In patients with multivessel coronary disease, incomplete revascularization after PCI is associated with poorer 1-year outcomes compared with treatment of all significant stenoses during the index hospitalization, a registry study shows. The increased risk is seen across patient subgroups.

“Because our study is observational, the question of whether the higher event rates in incompletely revascularized patients can be lowered with a treatment strategy aiming at full revascularization still remains unclear and cannot be answered in a registry study,” Kristina Hambraeus, MD, PhD, of Falun Hospital (Falun, Sweden), and colleagues write in the February 8 issue of JACC: Cardiovascular Interventions.

Incomplete revascularization has been tied to an elevated risk of recurrent cardiovascular events in prior observational studies and subgroup analyses of randomized trials. More complete revascularization, however, increases the complexity of the procedure, uses more radiation and contrast, and potentially carries a greater risk of complications.

Recent trials in STEMI patients have indicated an advantage for complete revascularization, resulting in a guideline change, but the issue remains unsettled across the spectrum of patients undergoing PCI.

Unselected Cohort of Swedish Patients

In the current study, the researchers compared outcomes following incomplete vs complete revascularization in an unselected cohort of patients with multivessel coronary disease and various types of presentation. The analysis included 23,342 patients included in the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) between January 1, 2006, and July 1, 2010.

About two-thirds of patients (65%) had incomplete revascularization at the end of PCI, defined as having any nontreated significant stenosis (at least 60%) in a coronary artery supplying more than 10% of the myocardium. These patients were older and more likely to be female, had more extensive coronary disease, and were more likely to present with STEMI than those who underwent complete revascularization.

Before accounting for those differences, incomplete revascularization was associated with higher rates of all-cause mortality (7.1% vs 3.8%), MI (10.4% vs 6.0%), repeat revascularization with PCI or CABG (23.6% vs 9.3%), and a composite of those 3 endpoints (33.4% vs 15.3%).

After adjustment by propensity score, incomplete revascularization remained predictive of the composite of death, MI, or repeat revascularization (HR 2.12; 95% CI 1.98-2.28), as well as death (HR 1.29; 95% CI 1.12-1.49) and a composite of death or MI (HR 1.42; 95% CI 1.30-1.56).

The greater risk of the 3-part composite endpoint was consistent regardless of type of presentation. But when looking at death specifically, incomplete revascularization was tied to an increased risk in patients with NSTE-ACS but not in those with STEMI or stable CAD.

Support for Complete Revascularization

In an accompanying editorial, Nir Ayalon, MD, and Alice Jacobs, MD, of Boston Medical Center (Boston, MA), say the study “adds to growing evidence suggesting that complete revascularization should be the preferred strategy in patients with multivessel coronary disease and that it is related to favorable outcomes.”

A key missing piece of information, however, is “whether incomplete revascularization was intended or the result of a procedural complication or an uncomplicated technical failure,” they add. Prior studies have shown that when an “incomplete” approach is planned, it is not related to risk of cardiac death or death/MI but is associated with subsequent CABG at 5 years, they report.

“Moving forward, it will be helpful to adequately evaluate a strategy of intended, incomplete, but functionally adequate PCI, particularly in patients deemed to be at high risk for complete revascularization (that may be unnecessary),” Ayalon and Jacobs write. “Careful consideration of the spectrum of incomplete revascularization employing catheter-based tools to measure fractional flow reserve and assess physiological and functional significance of coronary stenoses and newer imaging modalities to evaluate ischemia and viability may improve outcomes for patients across the continuum of stable ischemic heart disease, acute coronary syndromes, and STEMI.”

It remains to be seen “whether performing complete revascularization will improve outcomes in the presumably more complex, incomplete revascularization patient group in whom jeopardized myocardium remains,” they say.

In the meantime, the editorialists conclude, “absent robust evidence to inform our clinical practice guidelines and management decisions, it is the individual physician and patient who will continue to synthesize the clinical, angiographic, and procedural variables supported by anatomic, hemodynamic, and functional studies in addition to quality-of-life preferences and to determine together how much revascularization is enough revascularization.”

Sources: 
1. Hambraeus K, Jensevik K, Lagerqvist B, et al. Long-term outcome of incomplete revascularization after percutaneous coronary intervention in SCAAR (Swedish Coronary Angiography and Angioplasty Registry). J Am Coll Cardiol Intv. 2016;9:207-215.
2. Ayalon N, Jacobs AK. Incomplete revascularization in patients treated with percutaneous coronary intervention: when enough is enough [editorial]. J Am Coll Cardiol Intv. 2016;9:216-218.

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