OBJECTIVE -In some studies intensive diabetes treatment in patients with type 2 diabetes may be associated with increased cardiovascular events. It is not clear whether these events are related to hypoglycemic episodes. To determine whether episodes of hypoglycemia were more likely to be associated with cardiac ischemia than normoglycemia or hyperglycemia, we carried out a study in 21 patients with coronary artery disease (CAD) and type 2 diabetes treated with insulin who had good glycemic control.RESEARCH DESIGN AND METHODS -We carried out 72-h continuous glucose monitoring along with simultaneous cardiac Holter monitoring for ischemia. Patients also recorded symptoms of cardiac ischemia (chest pain) and symptoms of hypoglycemia.RESULTS -Satisfactory continuous glucose monitoring system recordings were obtained in 19 patients. We recorded 54 episodes of hypoglycemia (blood glucose Ͻ70 mg/dl; 26 of these were symptomatic) and 59 episodes of hyperglycemia (blood glucose Ͼ200 mg/dl; none symptomatic). Of the 54 episodes of hypoglycemia, 10 were associated with symptoms of chest pain, during 4 of which electrocardiographic abnormalities were documented. In contrast, only 1 episode of chest pain occurred during 59 episodes of hyperglycemia. No chest pain or electrocardiographic abnormalities occurred when the blood glucose was within the normal range. The difference between the frequency of ischemia during hypoglycemia and the frequency during both hyperglycemia and normoglycemia was statistically significant (P Ͻ 0.01). There were 50 episodes during which the blood glucose changed by Ͼ100 mg over a 60-min period, and ischemic symptoms occurred during 9 of these episodes (P Ͻ 0.01 compared with stable normoglycemia or hyperglycemia).CONCLUSIONS -Hypoglycemia is more likely to be associated with cardiac ischemia and symptoms than normoglycemia and hyperglycemia, and it is particularly common in patients who experience considerable swings in blood glucose. These data may be important in the institution of insulin treatment and attempting near-normal glycemia in patients with known CAD. Further research is needed to determine strategies to prevent ischemia associated with hypoglycemia. Diabetes Care 26:1485-1489, 2003D iabetes is associated with an increased risk of development of coronary artery disease (CAD). Patients with CAD and diabetes have higher mortality and morbidity than patients without diabetes. Data from studies such as the U.K. Prospective Diabetes Study suggest that very good glycemic control is associated with fewer cardiovascular events (1). However, tight glycemic control may increase the risk of hypoglycemia. Increased cardiovascular events were noted in the Veterans Affairs Cooperative Study on Glycemic Control and Complications (VA CSDM), after the institution of tight glycemic control (2). It is possible that acute hypoglycemia may trigger ischemia and cardiovascular events. Hypoglycemia and rapid changes in blood glucose have been shown to increase counterregulatory hormones such as epinephrine ...

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Left ventricular systolic dysfunction is mainly a result of coronary artery disease (CAD). Decrease in myocardial contractility results as a response to a chronic hypoperfusion state that produces a change in cardiac myocyte metabolism, resulting in a perfusion-contraction mismatch in which function is sacrificed for survival. If revascularization is performed in a timely fashion, metabolism can be restored leading to recovery of function. Through the use of noninvasive imaging modalities, assessing myocardial viability can be easily performed and will aid in selecting those patients who will benefit from revascularization. Viable myocardium can be identified by nuclear modalities that have a high sensitivity but a lower specificity, such as thallium-201 single photon emission computed tomography and positron emission tomography (PET); or by the use of dobutamine stress echocardiogram (DSE), which has a decreased sensitivity but a better specificity. A modality that is increasingly being used with an overall good sensitivity and specificity is contrast-enhanced magnetic resonance imaging. The purpose of this review is to explore the amount of myocardial viability that is relevant to pursue revascularization, since as myocardial function improves there is a decrease in morbidity and mortality from heart failure and arrhythmias.