Ischemia Testing Foretells Prognosis in Diabetic Patients with Asymptomatic CAD
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In diabetic patients who are at high risk of coronary artery disease (CAD) but asymptomatic, abnormal results on ischemic testing predict a 7-fold higher risk of progression to overt or silent CAD—even when patients undergo additional treatment for CAD. The findings were published online September 17, 2014, ahead of print in JACC: Cardiovascular Imaging.
| Methods |
| For the Basel Asymptomatic high-Risk Diabetics’ Outcome Trial (BARDOT), researchers led by Michael J. Zellweger, MD, of University Hospital (Basel, Switzerland), prospectively evaluated 400 asymptomatic patients with type 2 diabetes who had no history or current symptoms of CAD but were considered high risk. All underwent myocardial perfusion scintigraphy (MPS)—myocardial perfusion single-photon emission computed tomography—at baseline; those with abnormal findings were randomized to receive medical therapy or combined invasive and medical management, while those with normal findings continued to receive usual care. |
The primary endpoint considered 2 components of CAD progression:
|
Abnormal MPS was found in 87 patients (22%). Compared with
those in the normal MPS group, patients in the abnormal MPS group were older
and more likely to be men or smokers and to have peripheral vascular disease,
autonomic cardiac neuropathy, longer histories of diabetes, and higher levels
of systolic blood pressure, creatinine, and BNP.
Despite receiving treatment for CAD, patients with abnormal MPS at baseline had greater risk of MACE and ischemia or new scar—resulting in overt or silent CAD progression—at 2 years than did patients with normal findings. The difference in MACE was mainly driven by revascularization, though rates of cardiac death and MI both were numerically higher in the abnormal MPS group (table 1).
Table 1. Two-Year Results According to Baseline MPS
|
Normal MPS |
Abnormal MPS |
HR |
P Value |
MACE |
2.9% |
9.8% |
3.44 |
.011 |
Cardiac Death |
0.7% |
2.4% |
3.77 |
.184 |
MI |
1.0% |
3.7% |
3.77 |
.104 |
Revascularization |
2.0% |
7.3% |
3.90 |
.019 |
Ischemia or New Scar |
3.2% |
34.2% |
15.91 |
< .001 |
Overt or Silent CAD Progression |
4.6% |
35.6% |
11.53 |
< .001
|
Within the abnormal MPS group, patients were at similar risk of MACE regardless of whether they were assigned to receive medical therapy alone or alongside invasive treatment (HR 0.36; 95% CI 0.07-1.81). Because invasively managed patients had lower risk of ischemia or new scar, however, their likelihood of overt or silent CAD progression was reduced overall (OR 0.14; 95% CI 0.04-0.40).
Notably, only 65% of patients randomized to the invasive strategy were revascularized. No MACE occurred in revascularized patients. Scintigraphic results were more likely to normalize by 2 years in patients who underwent revascularization rather than receiving medical therapy alone (84% vs 46%; P < .001).
Direct Impact on Practice
“If patients with diabetes are clinically at high risk of CAD as in BARDOT, they should be considered for ischemia testing,” the researchers advise. Without evidence of CAD on MPS, they add, “the 2-year outcome will be benign without further anti-ischemic therapy and no need for repeat testing within 4 to 5 years. However, in [the approximately] 20% of patients with abnormal MPS, anti-ischemic therapy should be advised because every third patient will experience MACE or therapy-refractory silent CAD.
“Thus, these findings should directly impact daily practice and lead to corresponding adjustments in current guidelines,” they conclude. “The optimal type of therapy is still open to debate…. An appropriately sized randomized controlled trial is needed to settle this question.”
Dr. Zellweger and colleagues note that the results challenge the message of the DIAD study, which indicated screening is unnecessary. In addition, BARDOT provides the first trial evidence backing current European class IIb recommendations for ischemia testing in this subgroup, they report.
Source:
Zellweger MJ, Maraun M, Osterhues HH, et al. Progression to
overt or silent CAD in asymptomatic patients with diabetes mellitus at high
coronary risk. J Am Coll Cardiol Img.
2014;Epub ahead of print.
Disclosures:
- The study was supported by the Foundation for Cardiovascular Research, Basel; the Foundation of the Diabetes Association of Basel; Heider & Co; Pfizer; Roche; the Swiss Heart Foundation, Bern; the Swiss National Foundation for Research; and Takeda.
- Dr. Zellweger reports no relevant conflicts of interest.
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Caitlin E. Cox is News Editor of TCTMD and Associate Director, Editorial Content at the Cardiovascular Research Foundation. She produces the…
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