Study Compares Stents, Surgery in Diabetics with Multivessel Disease

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At 5 years after revascularization, diabetic patients with multivessel disease obtain better overall results with either coronary artery bypass graft (CABG) surgery or sirolimus-eluting stents (SES) than with bare-metal stents (BMS). However, long-term data published in the March 2011 issue of JACC: Cardiovascular Interventions indicate that CABG markedly decreases the need for repeat revascularization compared with either stent type.

Patrick W. Serruys, MD, PhD, of Erasmus Medical Center (Rotterdam, The Netherlands), and colleagues retrospectively analyzed the outcomes of 367 patients with diabetes and multivessel disease who took part in 2 iterations of the Arterial Revascularization Therapy Study (ARTS). Both ARTS-I and ARTS-II had the same inclusion criteria. ARTS-I randomized subjects to receive BMS or CABG, while ARTS-II was a nonrandomized, open-label trial designed to assess the safety and efficacy of SES compared with historical controls from ARTS-I.

Recent trials have suggested that DES in this patient population can match the safety of CABG up to 2 years, the paper reports. The current analysis obtained 5-year follow-up.

Some ‘Catch-up’ Seen with SES

The 5-year overall MACCE rate (composite of all-cause mortality, MI, cerebrovascular accident, or revascularization) was higher for patients treated with BMS than for those who underwent CABG or received SES (P < 0.001 for both comparisons). There was no mortality difference among the 3 groups. MI risk, however, was highest for BMS patients (P = 0.04 vs. SES patients) and equivalent between the CABG and SES groups (P = 0.76). Repeat revascularization was lower with CABG than with SES (P < 0.01), and in turn was lower with SES than with BMS (P = 0.02; table 1).

Table 1. Kaplan-Meier Estimates of Outcomes at 5 Years

Importantly, the incidence curves for MACCE illustrate that “although the event rate for patients treated with BMS and CABG reach an asymptomatic value at 1 year, events continue to accumulate for patients treated with SES in the ARTS-II trial. After 2 years this increase in events is partly explained by an increase in MI rates,” the paper notes, adding that this “catch-up” is more dramatic in diabetic than in nondiabetic patients. “The rate of repeat revascularization also continues to accumulate [for SES], approaching closer to that of the BMS-treated patients at 5 years.”

Based on the findings from ARTS, “CABG seems to have better [long-term] outcomes than PCI in a diabetic patient population by virtue of reducing repeat revascularization rates, making CABG the preferred treatment for this subgroup of patients with [multivessel disease],” Dr. Serruys and colleagues conclude. Further information about the efficacy of DES vs. CABG in this patient population will be provided by the ongoing FREEDOM trial, they add.

Some Caveats

 In a telephone interview with TCTMD, Michael E. Farkouh, MD, MSc, of Mount Sinai Medical Center (New York, NY), cautioned that the current analysis is not randomized. Not only are there baseline imbalances among the treatment groups but the analysis also is “grossly underpowered” to detect differences in hard clinical outcomes like mortality, he added.

“Going into this observational analysis, they really only had the power to show differences in repeat revascularization, or MACCE rates if you add in [that endpoint],” he said. “Therefore, you can’t say that there is no difference [in hard endpoints such as death, MI, or stroke]. All you can say is that in this analysis there was no difference.”

So while the results reassure that DES use in diabetics is “relatively safe,” they do not rule out the possibility that CABG may impart significantly lower mortality. “The lack of [observed] difference does not mean there is no difference,” Dr. Farkouh stressed.

In addition, “[w]hat’s striking right off the bat is that the differences in the MACCE rates really come down to repeat revascularization,” he said, noting that the rate for SES is “still quite high compared with CABG.”

The likelihood of repeat revascularization with PCI by itself is “not necessarily” enough to tip the scales toward CABG, Dr. Farkouh said: “You have a discussion with your patients, and some are willing to take the increased risk of repeat revascularization in order to forgo CABG, because CABG is very debilitating. . . . It’s a clinical decision between the physician and the patient that has a lot to do with the age of the patient, other comorbidities, and so on.”

One helpful tool in diabetic patients is the Syntax score, he noted, specifying that patients with higher Syntax scores are more likely to benefit from CABG. “So if your Syntax score is 22 or less, a low score, you probably have a fair chance that you won’t require repeat revascularization,” Dr. Farkouh said.

Another issue not explored by the ARTS analysis is how well patients are medically managed after DES, he added. “The better their risk factor control, the more likely they are to enjoy a benefit that’s similar to CABG.”

DES Moving on Up

In an editorial accompanying the paper, Koon-Hou Mak, MD, of the Yong Loo Lin School of Medicine (Singapore), however, agrees that the findings of Serruys et al back the findings of recent trials showing comparable safety between DES and CABG, although “the reason for outcome improvement among studies over time is uncertain.”

Duration of dual antiplatelet therapy is unlikely to have played a role, since most SES patients in ARTS-II only received the drugs for 3 months, Dr. Mak notes, suggesting that greater care in stent deployment and a return to high-pressure post-dilation technique may have had beneficial effects.

It has been 15 years since the BARI trial raised concerns about angioplasty in diabetic patients, he points out. “The field of interventional cardiology has progressed substantially since then, developing ideas from engineering and drug delivery,” such that DES are now likely the preferred device for interventions. Novel pharmacologic agents may further improve results, Dr. Mak notes, and while “newer generations of DES have not been shown to be fully comparable to CABG regarding the need for repeat revascularization, continuous innovation will narrow the efficacy gap further for patients with diabetes,” he writes.

Sources:

1. Onuma Y, Wykryzkowska JJ, Garg S, et al. 5-year follow-up of coronary revascularization in diabetic patients with multivessel coronary artery disease: Insights from ARTS (Arterial Revascularization Therapy Study)-II and ARTS-I trials. J Am Coll Cardiol Intv. 2011;4:317-323.
2. Mak K-H. The continuing diabetic drug-eluting stents saga: From very-late stent thrombosis to very-late late loss [editorial]. J Am Coll Cardiol Intv. 2011;4:324-326.

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