Incomplete Revascularization Puts Diabetics at Increased Risk of Long-term Events

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Patients with type 2 diabetes who receive incomplete revascularization for coronary artery disease experience worse long-term outcomes than their counterparts who have more complete revascularization, regardless of the choice of intervention, according to a post-hoc analysis published online April 10, 2012, in Circulation: Cardiovascular Interventions.

The main BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial randomized 798 type 2 diabetes patients to optimal medical therapy with or without prompt revascularization (either PCI or CABG at the operators’ discretion). After an average follow-up of 5.3 years, there was no difference between the groups in the primary endpoint of all-cause mortality or MACE (death, MI, or stroke).

For the current nonrandomized substudy, Leonard Schwartz, MD, of Toronto General Hospital (Toronto, Ontario), and colleagues looked at751 patients from BARI 2D who underwent early revascularization (264 receiving CABG and 487 PCI), analyzing the clinical impact of the completeness of revascularization.

Completeness was measured by the residual postprocedure myocardial jeopardy index, which is the ratio of the number of myocardial territories supplied by a significantly diseased epicardial coronary artery or branch that was not successfully revascularized, divided by the total number of myocardial territories.

Incomplete Revascularization Common

Thirty-one percent of patients had 1 diseased region, 37% had 2 diseased regions, and 31% had 3 diseased regions. Only 37.9% of patients had complete revascularization, with the rest having mildly incomplete (jeopardy index > 0, ≤ 33; 46.6%), or moderately or severely incomplete revascularization (index > 33%; 15.4%).

Patients undergoing CABG were less likely to have complete revascularization than those receiving PCI (32.2% vs. 41.1%) but also less likely to have moderately to severely incomplete revascularization (12.5% vs. 17.0%). Among patients undergoing PCI, 59% had incomplete revascularization, although this was intentional in all but 6%. In those undergoing CABG, 68% had incomplete revascularization, intentional in all but 10%.

However, postprocedure mean residual myocardial jeopardy index was equivalent between CABG patients (14.9 ± 15.0) and PCI patients (15.6 ± 18.8; P = 0.59).

There was an increased risk of death, MI, subsequent revascularization, and the composite endpoint of death, MI, or stroke for every 10-unit increase in the index measuring incomplete revascularization (table 1).

Table 1. Outcomes by Increasing Degree of Incomplete Revascularization

 

HR for 10-Unit Increase in Myocardial Jeopardy Index
(95% CI)
(n = 751)

P Value

Death

1.13 (1.01-1.25)

0.02

Subsequent Procedure

1.24 (1.13-1.36)

< 0.0001

MI

1.14 (1.00-1.29)

0.047

Death, MI, or stroke

1.14 (1.05-1.23)

0.0018


The same results held true when analyzed according to mildly or moderately/severely incomplete revascularization as separate categories, with the exception of death (P = 0.08).

On further analysis, subsequent revascularization was more likely with less complete revascularization, but only in patients undergoing PCI, while death, MI, and the composite endpoint were not affected by completeness for either revascularization procedure.

Revascularization Measure Too Strict?

In an e-mail communication with TCTMD, Dr. Schwartz explained that complete revascularization is difficult to achieve by any means.

“In patients with CAD, there are usually multiple lesions. Some of these are in arteries which have a small distribution and bypassing them or performing [PCI] is often not attempted because of risk, inaccessibility, questionable graftability, and uncertain impact on outcome,” Dr. Schwartz said.

Therefore, he said, the incidence of incomplete revascularization seen in this study of diabetics, who generally have more lesions than nondiabetic patients, was not unusual.

However, in a telephone interview with TCTMD, Jeffrey W. Moses, MD, of Columbia University Medical Center/Weill Cornell Medical Center (New York, NY), found the rate of incomplete revascularization to be quite high, questioning whether the score used to measure completeness might be too detailed or stringent.

“When you look at multivessel databases, the complete revascularization rates run at about 60% or greater,” Dr. Moses said. “However, in this group of predominantly single- and double-vessel disease, [the rate of incomplete revascularization] seems high on [both] the PCI and surgical end.”

Data Observational, but Expected

Dr. Schwartz cautioned that although BARI 2D was a randomized study, the substudy was not a randomization of complete vs. incomplete revascularization.

“It cannot be determined if the inability to completely revascularize was not just a marker of a poorer outcome related to, for example, the extent of disease,” he said.

However, Dr. Moses observed that although the study was observational, the outcome was not surprising, adding that if residual disease is left behind, it is logical to conclude that patients will have worse clinical outcomes. In fact, he pointed out that another recent study (Géneréux P, et al. J Am Coll Cardiol. 2012;Epub ahead of print) also found an association between the completeness of revascularization, as measured by Syntax score, and worse clinical outcomes at 30 days and 1 year.

As evidence of this association grows, both Drs. Moses and Schwartz agreed, physicians should adapt their approach to attenuate potential risk.

“That means that if you cannot give a complete revascularization, you should choose the method of revascularization that gives the patient the greatest chance of a complete procedure,” Dr. Moses said.

 


Source:
Schwartz L, Bertolet M, Feit F, et al. Impact of completeness of revascularization on long-term cardiovascular outcomes in patients with type 2 diabetes mellitus: Results from the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D). Circ Cardiovasc Interv. 2012;Epub ahead of print.

 

 

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Disclosures
  • Dr. Schwartz reports no relevant conflicts of interest.
  • Dr. Moses reports serving as a consultant for Boston Scientific.

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