Elsevier

Mayo Clinic Proceedings

Volume 91, Issue 11, November 2016, Pages 1535-1544
Mayo Clinic Proceedings

Original article
Impact of Stress Testing for Coronary Artery Disease Screening in Asymptomatic Patients With Diabetes Mellitus: A Community-Based Study in Olmsted County, Minnesota

https://doi.org/10.1016/j.mayocp.2016.07.013Get rights and content

Abstract

Objective

To evaluate the impact of screening stress testing for coronary artery disease in asymptomatic patients with diabetes in a community-based population.

Patients and Methods

This observational study included 3146 patients from Olmsted County, Minnesota, with no history of coronary artery disease or cardiac symptoms in whom diabetes was newly diagnosed from January 1, 1992, through December 31, 2008. With combined all-cause mortality and myocardial infarction as the primary outcome, weighted Cox proportional hazards regression was performed with screening stress testing within 2 years of diabetes diagnosis as the time-dependent covariate. For descriptive analysis, participants were classified by their clinical experience during the first 2 years postdiagnosis as screened (asymptomatic, underwent stress test), unscreened (asymptomatic, no stress test), or symptomatic (experienced symptoms or event).

Results

Among the screened and unscreened participants, 54% (1358 of 2538) were men; the mean (SD) age at diabetes diagnosis was 55 years (13.8 years), and 97% (2442 of 2520) had type 2 diabetes. In event-free survival analysis, 292 patients comprised the screened cohort and 2246 patients comprised the unscreened cohort. Death or myocardial infarction occurred in 454 patients (32 patients in the screened cohort and 422 in the unscreened cohort [5-year rate, 1.9% and 5.3%, respectively]) during median (interquartile range) follow-up of 9.1 years (5.3-12.5 years). Screening stress testing was associated with improved event-free survival (hazard ratio, 0.61; P=.004), independent of cardiac risk factors. However, while stress test results were abnormal in 47 of the 292 screened patients (16%), only 6 (2%) underwent coronary revascularization.

Conclusion

Although screening cardiac stress testing in asymptomatic patients with diabetes in this community-based population was associated with improvement in long-term event-free survival, this result does not appear to occur by coronary revascularization alone.

Section snippets

Patients and Methods

Using REP resources, we compared outcomes of asymptomatic diabetic patients who did or did not undergo a screening cardiac stress test within 2 years of their diabetes diagnoses according to the judgment of their physicians. This retrospective cohort study was approved by both the Mayo Clinic and Olmsted Medical Center institutional review boards. All participating patients had provided previous written permission approving the use of their medical records for research.

Study Participants

A total of 10,079 patients in Olmsted County received a diagnosis of diabetes between January 1, 1992, and December 31, 2008. From these patients, those without a history of CAD or heart failure were identified: 292 who had a screening stress test within 2 years of diabetes diagnosis (screened cohort), 2246 who were asymptomatic at 2 years and did not undergo stress testing within that time period (unscreened cohort), and 608 who became symptomatic, died, or had MI within 2 years (symptomatic

Discussion

This is the first large-scale, community-based study designed to analyze the impact of early screening cardiac stress testing in asymptomatic patients with diabetes. The unique methodology allowed inclusion of large numbers of patients and reduced referral bias. Screening cardiac stress testing was associated with improved long-term event-free survival (HR, 0.61; P=.004), independent of other cardiac risk factors. Although stress test results were abnormal in 16% of the patients, only 6 (2%) of

Conclusion

Screening cardiac stress testing in asymptomatic patients in a community-based cohort within 2 years of the diabetes diagnosis was associated with improved long-term event-free survival, despite a higher mean FRS in those who underwent screening. Coronary artery disease was suggested by stress test results in 16% of screened patients, and most received intensified medical therapy. Only 2% of screened patients underwent coronary revascularization, suggesting that improved outcomes may have been

Acknowledgments

Drs Bates and Omer contributed equally to this study. The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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    Grant Support: This study was supported in part by a grant from the Mayo Clinic Division of Cardiovascular Diseases, which supported biostatistical analysis. The study was made possible by the Rochester Epidemiology Project (grant number R01-AG034676; Principal Investigators: Walter A. Rocca, MD, MPH, and Jennifer L. St. Sauver, PhD).

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