Incomplete Revascularization Linked With Mortality in Multivessel Disease Patients

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In patients with multivessel disease who receive bare-metal stents (BMS), incomplete revascularization is associated with higher mortality risk as late as 8 years after treatment, according to a population-based study published online October 4, 2011, ahead of print in Circulation: Cardiovascular Interventions. 

To assess how the extent of revascularization might impact mortality, Edward L. Hannan, PhD, of the University of Albany (Albany, NY), and colleagues analyzed data from the New York State’s Percutaneous Coronary Intervention Reporting System on 13,016 multivessel disease patients implanted with BMS in 1999 and 2000. The study builds upon earlier research by the same group, extending follow-up from 3 to 8 years.

Complete revascularization was defined as a reduction of stenosis to less than 50% in all diseased (≥ 70% stenosis) lesions in major epicardial coronary vessels at the initial hospitalization or within 30 days after discharge before having a new MI.

Mortality Increase Slight But Significant

Complete and incomplete revascularization were obtained in 29.2% (n = 3,803) and 70.8% (n = 9,213) of patients, respectively. Those with incomplete revascularization were older and more likely to be Hispanic or black, have lower ejection fraction values, and have 3-vessel disease total occlusion. They also showed higher rates of comorbidities such as MI, cerebrovascular disease, PAD, and CHF.

To compensate for these differences, the researchers performed a propensity analysis that matched the complete revascularization cohort to an equal number of patients with incomplete revascularization who had similar baseline risk. Among the 3,803 pair-matched subjects, 8-year survival rates were higher among those with complete vs. incomplete revascularization (80.8% vs. 78.5%; P = 0.04).

The likelihood of mortality grew higher when more than one vessel was incompletely treated, although the difference did not reach statistical significance (table 1).

Table 1. Eight-Year Mortality Risk: Incomplete vs. Complete Revascularization

Adjusted HR (95% CI)

P Value

Overall

1.12 (1.01-1.26)

0.04

1-Vessel

1.11 (0.99-1.25)

0.08

Multivessel

1.20 (0.90-1.59)

0.22


Several subgroups were found to be at particularly high risk of death when treatment was incomplete, including those who had:

  • Ejection fraction  ≥ 40%
  • No history of MI
  • No CHF
  • Left anterior descending disease
  • Proximal vessel disease
  • No total occlusion

However, because none of these significantly interacted with the extent of revascularization, the authors suggest that the impact of incomplete treatment on long-term mortality is not highly dependent on baseline risk factors.

Judging the Percentage

Study coauthor Chuntao Wu, MD, PhD, of Penn State Hershey College of Medicine (Hershey, PA), told TCTMD in a telephone interview that he “expected a stronger impact of incomplete revascularization,” after previous research on the same population showed a 15% increase in 3-year mortality. Even though the difference of 2.3% in 8-year mortality between the 2 patient groups in this study was significant, Dr. Wu said that some might not see it as clinically relevant.

In a telephone interview with TCTMD, Jeffrey W. Moses, MD, of Columbia University Medical Center (New York, NY), commented that the findings do not make a “profound argument” for or against complete revascularization. “It sort of gives you an indication perhaps that the sicker patients are the ones more at risk. It’s all very suggestive, but it’s not very powerful,” he said.

Functional Importance Matters

While the methods of this study were similar to the researchers’ earlier work, Harold L. Dauerman, MD, of the University of Vermont (Burlington, VT), quickly pointed out a subtle change: the definition of significant disease shifted from at least 50% to at least 70% stenosis in the most recent iteration. This shift strengthens the study design, he said, because—as found in the FAME (Fractional Flow Reserve versus Angiography for Guiding PCI in Patients with Multivessel Coronary Artery Disease) trial—80% of lesions with 70% or greater stenosis are likely to be functionally significant.

Dr. Hannan, who discussed the study along with Dr. Wu, said they chose to use the 70% cutoff because it was a “conservative” parameter that is more in line with current definitions.

According to Dr. Dauerman, however, the current study is flawed in that the extent of revascularization was defined by anatomy alone and could have benefitted by more physiologic information.

“We have a fundamental difference in prognostication,” he explained in a telephone interview with TCTMD. “One is physiology guided and one is anatomic guided. I think the reason that this study shows a fairly weak relationship between [incomplete vs.] complete revascularization and mortality is that it doesn’t take into account whether the vessel that’s being left alone is functionally significant.”

Clinical Implications Uncertain

Despite the ongoing debate for or against complete revascularization, Dr. Hannan noted that this “study continues to show that there is a danger of incomplete revascularization and so certainly that is something that needs to be considered when doing this procedure.” Future research should include stress tests and fractional flow reserve, he said, but acknowledged that this can be difficult to do since these tests are not performed on all patients.

Though he favored pursuing these issues in a randomized trial, Dr. Dauerman said, “I’m not ready to conclude from this paper that we need to do all chronic total occlusions or that current clinical practice needs to be radically changed.”

Dr. Moses, meanwhile, suggested performing studies “looking at viable and non-viable myocardium and most importantly looking at more complex multivessel disease and double-vessel disease.”

 


Source:
Wu C, Dyer AM, King SB, et al. Impact of incomplete revascularization on long-term mortality after coronary stenting. Circ Cardiovasc Interv. 2011;Epub ahead of print.


Disclosures:

  • Drs. Wu and Hannan report no relevant conflicts of interest.
  • Dr. Moses reports serving as a consultant for Abbott Vascular and Boston Scientific.
  • Dr. Dauerman reports receiving research grants from Abbott Vascular and Medtronic, and serving as a consultant to Abbott Vascular, Medtronic, and St. Jude Medical.

 

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