Cardiac Conduction Abnormalities and Asymptomatic Myocardial Infarction in Type II Diabetes Mellitus Patients

Rajesh, C P (2008) Cardiac Conduction Abnormalities and Asymptomatic Myocardial Infarction in Type II Diabetes Mellitus Patients. Masters thesis, Stanley Medical College, Chennai.

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Abstract

INTRODUCTION: Diabetes Mellitus is not a single disease with a single cause. It is a multimetabolic disorder with wide variable spectrum of clinical features, encompassing different number of illnesses that share the single phenotype of hyperglycemia. Ubiquitous in distribution, it is a complex interaction of genetics, environmental factors and life style. The prevalence of diabetes mellitus in India is high and the case burden is rising every year. Diabetes affects all the organs of the body; these contribute to a very large extent to the morbidity and mortality of the disease. Hence the search for and the characterization of the abnormalities assume utmost importance. The involvement of cardiovascular system in Diabetes Mellitus is varied. It can be involved by microvascular and macrovascular pathology. Ischaemic heart disease, hypertensive heart disease and diabetic cardiomyopathy are the ways in which cardiac tissue is usually affected. The possible mechanism being Dyslipidemia, enhanced atherosclerosis, hypertension, diabetic macroangiopathy and metabolic alterations associated with diabetes. Adults with Diabetes have two to four times risk of developing heart diseases. There are numerous studies, which have highlighted these disorders. There are reports showing higher incidence of involvement of conducting tissue of heart in diabetes mellitus. There is a higher prevalence of right bundle branch block and atrioventricular block that cannot be accounted by the increased incidence of ischaemic heart disease alone. Higher incidences of these blocks are seen independent of ischaemic heart disease. Sinus node disorder in diabetes is mostly a manifestation of diabetic autonomic neuropathy. Early diabetic autonomic neuropathy is detected by estimating the heart rate variability. A depressed heart rate variability denotes a poor prognosis and often a marker for sudden cardiac death. Population based studies regarding the involvement of conducting tissue of heart in diabetes mellitus is rare; especially in South India. This study is performed to estimate the prevalence of conduction blocks, i.e., atrioventricular, fascicular block, and asymptomatic myocardial infarction by electrocardiogram in diabetic population in Stanley Medical College and Hospital and compare it with that of general population. AIM OF STUDY: 1. To study the prevalence of conduction blocks; namely atrio ventricular Nodal block, bundle branch blocks and fascicular blocks in electrocardiograms of asymptomatic Type II Diabetes Mellitus. 2. To compare this prevalence to that of age and sex matched asymptomatic control population. 3. To study the prevalence of electrocardiographic changes suggestive of myocardial infarction in asymptomatic Type II diabetes mellitus. 4. To compare this prevalence to that of controls. METHODOLOGY: This study was conducted in 150 Type II diabetes mellitus patients attending the Department of Internal Medicine, Government Stanley Medical College Hospital, Chennai and compared with 100 healthy age and sex matched controls. Study Groups: Group I - 150 patients with Type II Diabetes Mellitus. Group II - 100 healthy controls. These groups were selected on the basis of inclusion and exclusion criteria. Inclusion Criteria: 1. Type II Diabetes Mellitus, 2. Healthy controls. Exclusion Criteria: Patients with 1. Age above 50, 2. Documented Ischaemic heart disease, 3. History suggestive of previous angina, congestive cardiac failure, 4. Documented evidence of other cardiac disease like cardiomyopathy, 5. Valvular heart disease, 6. Congenital Heart Disease, 7. Myocarditis, 8. Alcoholism, 9. Hypertension, 10. Chronic obstructive pulmonary disease, 11. Any abnormalities detected in the physical examination of cardiovascular System, 12. Drugs – β blockers, Digoxin, 13. Post menopausal females, 14. Features of hypothyroidism, 15. Random blood sugar > 140 mg/dL for the controls, 16. Anaemia < 10 gm/Dl, 17. Uremia. The cases and the control were subjected to thorough physical examination. Blood was taken for estimation of blood sugar, serum cholesterol and renal function tests. A 12 lead ECG with rhythm strip was taken. RESULTS: The study population consisted of 150 non-insulin dependent diabetes mellitus. The control was made up of 100 subjects. The study population was made of 72 females (48%) and 78 males (52%). Among the control population, there were 45 females (45%) and 55 males (55%). Among the diabetic population, the mean age was 40.64 years with a standard deviation of 3.95 years. Among the control group, the mean age was 39.35 and the standard deviation 4.36 years. In the diabetic population 18 males were smokers (23.07%), compared to 11(20%) males in controls. There were no female smokers in either group. The mean cholesterol value in study group was 177.85 with a standard deviation of 15.45. The values in control group were 175.3 and 14.40 respectively. The body mass index of diabetic females had a mean of 22.78 with a standard deviation of 1.98%, the control group females had a mean of 22.48 with a standard deviation of 1.52. In the male diabetes, the mean of body mass index was 23.79 with a standard deviation of 1.78%. The control group males had a mean of 22.98 and a standard deviation of 1.80. Thus the diabetic and control population had equal age and sex distribution and matched for serum cholesterol, body mass index and smoking habits, which are possible confounding factors. Prevalence of right bundle branch blocks in diabetics was 11% (16/150) and in controls 3% (3/100). The difference in prevalence was significant with a P value of less than 0.05. The prevalence of right bundle branch blocks in diabetics less than 8 yrs duration was 10% (11/110) and in those with more than 8 yrs duration it was 12.5% (5/40). The prevalence of left bundle block in diabetics was 1.3% (2/150) compared to 1% (1/100) in control population. The results are not statistically significant. The prevalence of left anterior fascicular block was 8% (12/150) in diabetic population compared to 7% (7/100) in control population. The results are not statistically significant. No left posterior fascicular block were reported in either diabetic or control group. The prevalence of atrioventricular block was 4% (6/150) in diabetic population and 3% (3/100) in control population. All were first-degree blocks. The results are not statistically significant. The prevalence of asymptomatic myocardial infarction was 10% (15/150) in diabetic population and 2% (2/100) in control population. Chi-square test was employed to test the significance of the difference between the proportions, which were compared. CONCLUSIONS: The study on 150 non-insulin dependent diabetes mellitus showed that right bundle branch block occurred in 11% (16/150) of Diabetic population. When compared to the control population, this is statistically significant. The prevalence of left anterior fascicular block was higher in diabetics 12/150 (8%) than in control population, but this was not statistically significant. The prevalence of asymptomatic myocardial infarction was 15/150 (10%) in diabetics compared to the control population, a statistically significant difference. The prevalence of left bundle branch block and atrioventricular blocks is comparable in both diabetic and control population. Cardiovascular complications form a very large percentage of diabetic morbidity and mortality. Hence, early and comprehensive evaluation of cardiovascular system should be given priority in the long-term management of diabetic patients. ECG at regular intervals can contribute significantly towards assessing the prognosis of Type II DM patients.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Cardiac Conduction Abnormalities ; Asymptomatic Myocardial Infarction ; Type II Diabetes Mellitus Patients.
Subjects: MEDICAL > General Medicine
Depositing User: Subramani R
Date Deposited: 23 Mar 2018 16:03
Last Modified: 23 Mar 2018 16:03
URI: http://repository-tnmgrmu.ac.in/id/eprint/6493

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