Shah B, Danoff A, Radford MJ, Rolnitzky L, Sedlis SP. Periprocedural Management of the Patient With Diabetes Mellitus Undergoing Coronary Angiography: Current Practice. Arch Intern Med. 2012;172(19):1514-1516. doi:10.1001/archinternmed.2012.3630
Author Affiliations: Department of Medicine, Divisions of Cardiology (Drs Shah and Sedlis) and Endocrinology (Dr Danoff), VA New York Harbor Health Care System, New York Campus, New York; and Department of Medicine, Division of Cardiology (Drs Shah and Radford), and Department of Environmental Medicine, Division of Biostatistics (Ms Rolnitzky), New York University School of Medicine, New York.
Despite advances in procedural technique and pharmacotherapy, patients with diabetes mellitus (DM) experience worse outcomes than patients without DM undergoing percutaneous coronary intervention (PCI).1 Periprocedural hyperglycemia is associated with adverse clinical outcomes in patients undergoing PCI,2- 5 and studies have suggested that treating periprocedural hyperglycemia may improve outcomes by attenuating glucose-mediated ischemic injury at the time of PCI.6,7 Simple preventive strategies, such as continuing long-acting hypoglycemic medications, have not been evaluated, and there are no guidelines for periprocedural use of these medications.
We conducted an anonymous electronic survey of cardiologists referring patients for coronary angiography using the American Heart Association Cardiology Fellows Society of Greater New York and the Society of Cardiovascular Angiography and Interventions from March through July 2011. Of the 144 survey responders, 24% were fellows-in-training, and 33% were faculty at a medical school. Among this cohort, 60% believed that hyperglycemia at the time of PCI is harmful, and 94% believed that hypoglycemia at the time of PCI is harmful.
Although most clinicians routinely hold oral hypoglycemic medications prior to angiography, substantial numbers do not, with nearly half routinely continuing thiazolidinediones on the morning of coronary angiography (Table). Clinicians are more likely to continue insulin-based regimens than oral medications, but again there is no uniformity of practice. In patients with uncontrolled DM (glycosylated hemoglobin level >10% or blood glucose levels >200 mg/dL), a little more than one-third of physicians reported they would change their usual practice and continue hypoglycemic medications prior to coronary angiography. (To convert glycosylated hemoglobin to a proportion of total hemoglobin, multiply by 0.01; to convert serum glucose to millimoles per liter, multiply by 0.0555.)
The risk of hypoglycemia seems to be a major factor preventing physicians from continuing long-acting hypoglycemic medications prior to PCI. Delays in scheduled cardiac catheterization procedures frequently occur, and, therefore, uncertainty exists regarding how long a patient will be fasting prior to his or her coronary angiogram. However, hypoglycemia is not likely to complicate routine coronary angiography because patients with a procedure scheduled for late afternoon are usually given permission to have a light breakfast and to eat relatively soon after the procedure is completed even when conscious sedation is administered. Furthermore, there is substantial variability in eating patterns and stress levels on the day of PCI, which may lead to hyperglycemia at the time of arterial access. This may explain why most physicians report continuing at least half the dose of long-acting insulin in all patients with DM prior to angiography.
Our data suggest that physicians are influenced by the pharmacologic properties of the various hypoglycemic agents when designing management strategies for patients with DM undergoing coronary angiography. For example, thiazolidinediones and glargine-insulin are unlikely to cause sudden hypoglycemia in the setting of variable eating patterns. Physicians are, therefore, less likely to hold thiazolidinediones compared with sulfonylureas prior to cardiac catheterization. Similarly, physicians are more likely to continue full-dose glargine-insulin than neutral protamine Hagedorn (NPH)-insulin on the day of coronary angiography. Thus, it is a cause for concern that the management of patients treated with metformin reflects a lack of knowledge of the pharmacologic properties of this drug. Metformin is contraindicated in patients with chronic kidney disease owing to the risk of lactic acidosis at very high metformin concentrations. However, in patients with normal kidney function, renal function is unlikely to change following angiography unless contrast-induced nephropathy develops, a complication that occurs 48 to 72 hours after contrast exposure. The half-life of metformin is 2 to 5 hours, and, therefore, the drug label instructs patients to stop the medication for 48 hours after contrast exposure. Nevertheless, 88% of physicians in the current survey report holding metformin prior to coronary angiography. Furthermore, of these physicians, 28% report holding metformin for both 2 days before and 2 days after coronary angiography.
Although the response rate to this survey was low, and we have no data on nonresponders, we obtained a sample of physicians at various stages of practice, including fellows-in-training and attending physicians, in both private practice and academics. Survey responders may also have self-selecting features. For example, only those who believe this is an important topic of discussion may have responded to the survey. However, we still demonstrate clinical equipoise in the management of hypoglycemic medications in the patient with DM undergoing coronary angiography.
We conclude that there is considerable variability in the management of hypoglycemic medications by cardiologists sending patients for coronary angiography. An evidence base to better establish optimal goals for glycemic control in the setting of PCI and education of physicians to avoid premature discontinuation of DM therapies is needed. Furthermore, prospective randomized studies are warranted to determine if continuing long-acting hypoglycemic medications prior to PCI is safe and has a beneficial effect on long-term clinical outcomes.
Correspondence: Dr Sedlis, Department of Medicine, Division of Cardiology, VA New York Harbor Health Care System New York Campus, 423 E 23rd St, 12 West, New York, NY 10010 (email@example.com).
Published Online: September 10, 2012. doi:10.1001/archinternmed.2012.3630
Author Contributions: Dr Sedlis had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Shah, Danoff, and Sedlis. Acquisition of data: Shah. Analysis and interpretation of data: Shah, Danoff, Radford, Rolnitzky, and Sedlis. Drafting of the manuscript: Shah and Sedlis. Critical revision of the manuscript for important intellectual content: Shah, Danoff, Radford, and Rolnitzky. Statistical analysis: Shah and Rolnitzky. Administrative, technical, and material support: Shah. Study supervision: Danoff and Sedlis.
Financial Disclosure: None reported.
Funding/Support: This study was supported in part by grant 1UL1RR029893 from the National Center for Research Resources, National Institutes of Health.
Additional Contributions: We greatly appreciate all the cardiologists who participated in this survey. We thank Georgina Lopez-Cruz and Khusrow Niazi, MD, from SCAI, Susan Bishop and Mary Gonzalez from the AHA Cardiology Fellows Society of Greater New York, and Rebecca Ortega and Sohah Iqbal, MD, from the Society for Cardiovascular Angiography and Interventions–Women in Innovations organization for distributing this electronic survey to their respective organizations.