A Study on the prevalence of Asymptomatic Ischemic Heart Disease in Diabetic Women and association of Cardiac Autonomic Neuropathy with Silent Myocardical Ischemia
INTRODUCTION:
Patients with diabetes have a 2-4 fold increase in risk of CAD. Better implementation of therapies that reduce cardiovascular risk in diabetic patients will require moving beyond the traditional primary focus on glycaemic control. A working knowledge of the effects of diabetes
mellitus on the heart & blood vessels will aid physicians caring for these patients. In general population women experience relative protection from myocardial infarction and usually develop CAD approximately 10 years later than men. However diabetes blunts the cardiovascular benefit
of female gender.
In the first national health & nutrition examination survey
(NHANES) & the NHANES epidemiologic follow up survey conducted 10 years apart, age adjusted mortality decreased in non-diabetic men & women, less so in diabetic men, but increased by 23% in diabetic women.
In the Gruppo Italino per 10 studio della sopravvivenza bell Intarto miocardio – 2 (GISSI – 2) study of thrombolytic therapy in patients with myocardial infarction, diabetes increased the rate of death in men by 40%
and women by 90%.
Diabetic Autonomic neuropathy is the most common and
troublesome complication of type 2 Diabetes mellitus. Cardiovascular Autonomic neuropathy is a common form of Autonomic neuropathy causing abnormalities in heart rate control, central and peripheral
vascular dynamics. Cardiac autonomic neuropathy has been linked to postural hypotension, exercise tolerance, enhanced intra operative cardiovascular lability, increased incidence of asymptomatic ischemia, myocardial infarction and decreased likelihood of survival after myocardial infarction. Hypothesis concerning the multiple etiologies of
diabetic neuropathy include metabolic insult to nerve fibers, neurovascular insufficiency, autoimmune damage and neuro-humoral growth factor deficiency. Cardiac autonomic neuropathy which is considered to be a cause for asymptomatic CAD in diabetics is tested by history and simple bedside tests. Its presence has been correlated with the silent myocardial ischemia.
AIM OF THE STUDY:
1. To study the prevalence of asymptomatic ischemic heart disease in diabetic women by exercise stress test.
2. To correlate the presence of cardiac autonomic neuropathy with the asymptomatic ischemic heart disease.
MATERIALS AND METHODS:
Place of Study:
Institute of Internal Medicine, Madras Medical College & Government General Hospital, Chennai.
Study Population:
Of the 107 patients enrolled for the study who attended out patient clinic of institute of internal medicine, Government General Hospital, 30 patients were selected for the treadmill test and presence of cardiac autonomic neuropathy in them was tested by history and simple bed side tests. Other 77 patients are excluded as per exclusion criteria.
Inclusion Criteria:
1. Known diabetic women on treatment (OHA & insulin therapy),
2. Diabetic women not on treatment for CAD,
3. Patients not on beta blockers,
4. Duration of diabetes within 10 years,
5. Echocardiography normal.
Exclusion Criteria:
1. Patients with peripheral vascular disease as evidenced by absent peripheral pulses,
2. Type 1 diabetes mellitus,
3. Known case of coronary artery disease,
4. Signs of left ventricular failure,
5. Uncontrolled systemic hypertension,
6. High risk unstable angina,
7. Age > 65 yrs,
8. Other absolute contraindications for exercise stress test.
STATISTICAL ANALYSIS:
Statistical analysis was carried for 30 subjects after categorizing each variable. Autonomic neuropathy bedside tests are performed for all the patients. Age, duration of diabetes, BMI, systemic hypertension, menopause and percentage of CAN positivity in TMT positive and
negative group were analyzed. The significance of difference in mean between means were calculated using z test and difference in proportions using chi-square statistic.
Statistical significance is taken when P < 0.05. Statistical analysis was carried out using standard formulae. Microsoft excel 2003 and SPSS (statistical package for social sciences) version 13.0 softwares were used for data entry and analysis.
CONCLUSION:
1. The prevalence of asymptomatic ischemic heart disease was higher in diabetic women when compared to non diabetics. About one third of diabetic women are having asymptomatic ischemic heart disease which can be detected by simple treadmill test.
2. Prevalence of cardiac autonomic neuropathy was higher in
treadmill positive patients who are otherwise asymptomatic. This shows that there is significant association between silent myocardial ischemia and cardiac autonomic neuropathy in diabetic population.
3. Poor exercise capacity was noted in the TMT positive but
otherwise asymptomatic diabetic women
