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Despite still experiencing elevated event rates, diabetic patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) stand to derive at least as much relative benefit as nondiabetic patients from an invasive vs. conservative treatment strategy, according to a meta-analysis published July 10, 2012, in the Journal of the American College of Cardiology.

Researchers led by Michelle L. O’Donoghue, MD, of Brigham and Women’s Hospital (Boston, MA), conducted a meta-analysis of 9 randomized trials in NSTE ACS patients (n = 9,904) that identified invasive and conservative treatment strategies and reported cardiovascular events through 12 months. Overall, 18.1% (n = 1,789) of the participants had diabetes.

Diabetes Does Not Preclude Benefit

At 12 months, the rate of the primary composite endpoint of death, nonfatal MI, or ACS-related rehospitalization was higher in diabetic vs. nondiabetic patients, as was each of its components (table 1).

Table 1. Outcomes at 12 Months According to Diabetes Status

An invasive strategy had no significant effect on the likelihood of cardiovascular events overall, death, or rehospitalization in either diabetic or nondiabetic patients. But patients with diabetes stood to gain a substantial reduction in nonfatal MI (table 2).

Table 2. Outcomes at 12 Months: Early Invasive vs. Conservative Strategy

With invasive treatment, the absolute reduction in fatal MI risk was 3.7% for diabetics and 0.1% for nondiabetics (P = 0.02 for interaction).

Diabetics had a comparable reduction in death or MI with an invasive strategy regardless of whether they also had elevated biomarkers or ST-segment deviation. Among nondiabetic patients, however, those with elevated biomarkers stood to derive greater benefit from an invasive strategy, whereas there was no apparent advantage in patients who were nondiabetic and biomarker negative.

Why Only Nonfatal MI?

In a telephone interview with TCTMD, Deepak L. Bhatt, MD, MPH, of Brigham and Women's Hospital, said that changes in interventional strategies and the definition of diabetes over time may explain why the only endpoint to differ between the subgroups was nonfatal MI.

“Another reason could just be . . . statistical power,” he proposed, adding that the findings “could also have to do with things like diffuseness of disease. Diabetics tend to have much more diffuse disease than nondiabetics, so diabetic patients tend to be more likely to have plaque rupture. It might just also have to do with the fact that MI risk is much higher in diabetic patients.”

But the main message of the analysis remains the benefit of an invasive strategy in ACS, particularly when talking about higher risk patients, Dr. Bhatt stressed. “We’ve got a pretty consistent message now from a number of contemporary randomized clinical trials and a number of meta-analyses,” he said, mentioning positive biomarkers, dynamic ECG changes, and diabetes as factors that determine “the sorts of patients who really ought to go to the cath lab, barring any contraindications.”

Registry data, however, still show underutilization of catheterization in those populations, he said. “There has been so much scrutiny of intervention these past couple of years—questions of appropriateness—but that really all pertained to stable coronary artery disease. What’s sometimes lost in all that noise is that with suspected ACS, the standard of care in patients who are at moderate or high risk remains going to the cath lab and then revascularization as appropriate based on the coronary anatomy.”

In an e-mail correspondence with TCTMD, Dr. O’Donoghue agreed, noting, “The current findings provide important reassurance to clinicians and interventional cardiologists that diabetic patients derive at least as much benefit from an invasive strategy as nondiabetic patients. Since diabetic patients have a higher rate of cardiovascular events in the post-ACS setting, the absolute benefit that they derive from an invasive strategy may be greater than nondiabetic patients.”

Dr. Bhatt said the take-home message for clinicians is to be as aggressive with diabetics as with nondiabetics, even though this can be challenging given that patients with diabetes tend to have more comorbidities and to be at higher risk for contrast-induced nephropathy.

Need for Prospective Trial

In a telephone interview with TCTMD, Robert L. Wilensky, MD, of the Perelman School of Medicine at the University of Pennsylvania (Philadelphia, PA), praised the analysis for being “probably the best proof that an early invasive strategy” is superior in the diabetic population, but he pointed out that its data may be dated.

“Four of the 9 studies took place prior to 2000, six were published prior to 2005, and the latest study published in 2012 only had 184 patients,” he noted. As a consequence, the studies offer limited information on DES and newer pharmacologic treatments for ACS.

According to Dr. Wilensky, a timely prospective trial in patients with both diabetes and ACS is in order.

Study Details

In the invasive arm, the prevalence of revascularization was similar between diabetic and nondiabetic patients (67.8% vs. 66.0%, P = 0.31). Diabetic patients were more likely to undergo CABG, however (31.9% vs. 25.9%, P < 0.001). Overall, patients with diabetes tended to be older and were more likely to be female and to have hypertension, hyperlipidemia, and history of MI than nondiabetics.

 

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Source:
O’Donoghue ML, Vaidya A, Afsal R, et al. An invasive or conservative strategy in patients with diabetes mellitus and non–ST-segment elevation acute coronary syndromes: A collaborative meta-analysis of randomized trials. J Am Coll Cardiol. 2012;60:106-111.

 

 

Related Stories:

• Meta-analysis: Early Invasive Approach Favored for NSTE ACS
• Urgent Intervention Improves Survival in ACS Patients

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