PARIS – Undetected diabetes and prediabetes are pervasive in patients undergoing percutaneous coronary intervention, and they’re associated with a sharply increased risk of major adverse cardiovascular events, according to the results of the potentially practice-changing BIO-RESORT Silent Diabetes Study, Clemens von Birgelen, MD, PhD, reported at the annual congress of the European Association of Percutaneous Cardiovascular Interventions.

“Our data support screening PCI all-comers for silent diabetes, which may help identify patients with an increased event risk and improve their therapy,” said Dr. von Birgelen, professor of cardiology at the Thoraxcentrum of Twente, a high-volume center for cardiac interventions in Enschede, the Netherlands.

He presented the 1-year follow-up results of the prospective, observational BIO-RESORT Silent Diabetes Study, in which 988 Dutch PCI all-comers without known diabetes underwent screening for abnormal glucose metabolism 6 weeks after the procedure.

A substantial one-third of subjects turned out to have abnormal glucose tolerance according to World Health Organization criteria and an International Expert Committee Report (Diabetes Care. 2009 Jul;32[7]:1327-34). In a multivariate analysis, their 1-year rate of the primary study endpoint – target vessel failure, a composite of cardiac death, target vessel-related MI, or target vessel revascularization – was an adjusted 2.2 times greater than in the 788 normoglycemic patients.

Moreover, among the 7% of study participants who met diagnostic criteria for silent diabetes, the risk of target vessel failure was more than 4.4 times greater than in the normoglycemic group.

“To a very great extent, periprocedural MI is the driving force behind this difference that we saw. From a biological point of view, I think that the vulnerability of the vessel in the diabetic or prediabetic patient features more brittle plaque with a higher risk of cholesterol embolization, and with more plaque mass that can be pushed to the side so that side branch vessels can become occluded, leading to periprocedural MI,” he observed.

Glucose metabolism was assessed in all participants by two methods using the conventional cutoffs: a 2-hour oral glucose tolerance test (OGTT), and the combination of fasting plasma glucose and hemoglobin A1c. By OGTT, 7% of patients had silent, previously unrecognized diabetes and another 13% had prediabetes. Using the combination of fasting plasma glucose and HbA1c, a total of 25% of subjects had silent diabetes or prediabetes. Fully 33% of participants had abnormal glucose metabolism by one yardstick or the other.

“What we have seen is there is a group of patients that are missed with either. With the OGTT you don’t see all the diabetics, and with HbA1c and fasting blood glucose you also miss some patients,” said Dr. von Birgelen.

The 1-year cumulative incidence of target vessel failure was 13.2% in patients with silent diabetes as identified by the OGTT and 12.1% in those detected by the alternative method, compared with rates of 2.8% and 3.1%, respectively, in normoglycemic PCI patients. The event rate was 6.1% in patients with prediabetes by OGTT and similar at 5.5% in those found to be prediabetic based on fasting blood glucose and HbA1c, versus rates of 2.8% and 3.1%, respectively, in normoglycemic patients.

“The findings of this study suggest that post-PCI event risk associated with hyperglycemia is a continuum without a clear threshold effect, extending well beyond the threshold that currently defines diabetes,” Dr. von Birgelen said.

Once again, it’s worth emphasizing that the elevated target vessel failure rates seen in patients with abnormal glucose metabolism were due mostly to increased rates of acute MI within the first 24 hours after PCI. The target vessel–related MI rate was 10.3% in patients with silent diabetes, compared with just 1.8% in normoglycemic controls.

Asked what the take-home message for clinicians is from this study, he noted that the Netherlands has a relatively low prevalence of diabetes, and a highly developed primary care medicine system.

“We have a very good one-to-one relationship between the patient and the GP. So if we find 7% silent diabetes and up to one-third of patients with undetected abnormal glucose tolerance in a country with a relatively low prevalence of diabetes, you may expect that in other countries with a higher prevalence and perhaps a less developed primary care system the rate may be much, much higher,” Dr. von Birgelen cautioned.

The implications for the daily clinical practice of interventional cardiology are clear, he continued: “We’ve seen in several trials that the new stents are doing a fantastic job. So if we want to further improve the outcomes in our patients we have to do something else. We should look for subgroups of our PCI patients who have a particularly high risk. And we all realize that diabetics are such a problem, but I think we have shown that the prediabetic patients are also important. So we should identify and pretreat these patients, perhaps with aggressive lipid-lowering therapy during the weeks before a scheduled elective PCI.”

“There are data showing that with aggressive lipid-lowering you might reduce the risk of periprocedural MI,” the cardiologist noted.

As a practical matter, screening via fasting blood glucose and HbA1c is probably the way to go in clinical practice, according to Dr. von Birgelen.

“In this study, we performed the OGTT because it is still considered by many the gold standard. But there is increasing evidence favoring HbA1c data and fasting blood glucose,” he said.

Other possible pre-PCI interventions worthy of consideration in patients found to have previously unsuspected abnormal glucose tolerance might include medical therapy aimed at normalizing glucose metabolism, as well as perhaps resorting to the most potent forms of dual-antiplatelet therapy in patients with stable angina who have impaired glucose tolerance. However, these are possibilities that should be tested in randomized controlled trials before widespread adoption, he added.

The BIO-RESORT Silent Diabetes Study, which will continue for 5 years of post-PCI follow-up, is a prespecified substudy of the previously reported BIO-RESORT trial, which addressed another issue entirely. It was a three-arm, patient-blinded clinical trial comparing 1-year safety and efficacy outcomes in nearly 3,500 PCI patients randomized to PCI with very thin strut biodegradable polymer everolimus- or sirolimus-eluting stents or a durable polymer zotarolimus-eluting stent. Outcomes proved noninferior across the three treatment groups (Lancet. 2016 Nov 26;388[10060]:2607-17).

Dr. von Birgelen observed that the silent diabetes study broke new ground. Prior studies of PCI outcomes in patients with unrecognized diabetes were limited to recipients of plain old balloon angioplasty, bare metal, or first-generation drug-eluting stents. And studies of PCI in patients with unrecognized prediabetes are virtually nonexistent.

As the principal investigator for both the parent BIO-RESORT trial and the silent diabetes substudy, Dr. von Birgelen received research grants from Biotronik, Boston Scientific, and Medtronic, the cosponsors. He applauded the three companies for funding the silent diabetes substudy in the interest of science even though it had no commercial relevance to their stent businesses.

bjancin@frontlinemedcom.com

BIO-RESORT: A mandate to prescreen PCI patients for silent diabetes