[Silent myocardial ischemia during Holter monitoring in patients with diabetes mellitus]. / Isquemia miocárdica silente durante la monitorización con Holter en pacientes con diabetes mellitus.

UNLABELLED: To evaluate the prevalence and characteristics of silent myocardial ischemia in asymptomatic patients with non insulin dependent diabetes mellitus, 50 diabetic patients (24 males, 26 females; mean age +/- SD = 58.3 +/- 6.4 years) with a normal resting electrocardiogram were prospectively studied. The total group underwent 48 hours electrocardiographic Holter monitoring, medical history, physical examination an a test for cardiac autonomic neuropathy. Serum levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides and Hb A1c were determined. An ischemic episode was defined as asymptomatic ST-segment depression greater than or equal to 1 mm, greater than or equal to 1 min. Day-to-day variability was studied. Six hundred and forty one episodes with a total duration of 1,014 minutes of ischemia were recorded in 29 patients (58%). The mean number of episodes in 48 hours per patients was 19.2 +/- 21.9 and the mean time of ischemia over this period was 149 +/- 374 minutes. The average heart rate at the onset of the episodes was 95.2 +/- 8.4 beats per minute. Two hundred and ninety two (45.6%) episodes occurred without heart rate changes and in 349 (54.4%) episodes an increase in heart rate was detected at the onset of the episode. An important day-to-day variability in the number of episodes (73.8 +/- 29.5%) and ischemia duration (76.9 +/- 88.8%) was found. Fifteen patients had no ischemic episodes in either the first or second monitoring day. Silent ischemia was related to higher levels of total cholesterol (p less than 0.05), LDL-cholesterol (p less than 0.05) and Hb A1c (p less than 0.01) and was associated to diabetes complications: retinopathy (p less than 0.001), peripheral vascular disease (p less than 0.01), polyneuropathy (p less than 0.05), nephropathy (p less than 0.05), and impotence (p less than 0.01). Silent ischemia was not associated to abnormal test for cardiac autonomic neuropathy. CONCLUSIONS: prevalence of silent myocardial ischemia during daily activities in asymptomatic diabetic patients is very high (58%). Both an increase in oxygen demand and a decrease in oxygen supply may be involved in its pathophysiology. In diabetic patients silent ischemia is related to the presence of other risk factors for coronary artery disease and to diabetes complications and shows a marked day-to-day variability.