Comparative study of Left Ventricular Function by Echocardiography in Type 2 Diabetes Mellitus Patients With and Without Retinopathy

INTRODUCTION: Diabetes mellitus is a disease whose incidence is increasing worldwide and gaining epidemic proportions. Among all its complications, cardiovascular disease is in majority, the frequent reason for mortality. Over the last 30 yrs, numerous statistical, clinical and post-mortem studies have identified diabetic cardiac disease to be a separate clinical variable. Numerous studies have shown diabetes can affect the structure as well as functions of the heart even without conventional threat factors such as coronary artery disease and hypertension. Diabetic cardiomyopathy has been advocated as an independent cardiovascular disease and multiple mechanisms such as microvascular pathology, autonomic dysfunction, disorders in metabolic pathways and interstitial fibrosis have been proposed as causative factors. However, the accurate aetiopathogenesis of diabetic cardiomyopathy is not clear. New studies prove that diseases involving both the microvasculature and macrovasculature are associated with coronary events. Diabetic cardiomyopathy is characterised by defects in functions of both systole and diastole. Diabetic heart disease’s spectrum progresses from being normal to preclinical dysfunction of diastole and systole, leading to overt echocardiographic indices of evident LV dysfunction and ultimately fully blown heart failure with symptoms. In patients sans overt disease at beginning, the occurrence of subclinical ailment has association with augmented risk of cardiac disease, with the amplified risk of overall death as 3 for men and 1.7 in women. Apart from the mortality, there is impairment of functional capacity as well. After the onset of full blown heart failure signs and symptoms the prognostic prospects are generally worse. Hence, measures to identify risk variables contributing to this burdensome cardiac failure in subjects of diabetes mellitus are crucial in decreasing the associated moribund status. Current statistics from the study of Atherosclerosis Risk in Communities (ARIC) has exhibited a connection involving retinopathy, and heart failure development. The former is a microvascular disease indicator and the latter is traditionally viewed as a macrovascular disease. With more worsening of retinopathy severity, the mass of left ventricles increased, so also that of atrium and the systolic fraction decreased. These findings were found independent of influential confounding variables. Another study namely the Multi-Ethnic Study of Atherosclerossis (MESA) also established that retinopathy was coupled with accelerated remodeling of cardiac structures as evidenced by MRI of the heart in diabetic patients. Thus the studies lead to a possible suggestion that there exists a probable microvascular involvement in the concurrence of cardiac dysfunction coupled with diabetes or a potential link between microvascular retinopathy and the so called macrovascular heart disease due to common pathophysiological pathways of both disorders. In an era where both diabetes and heart failure contribute to the overall burden of the medical system, it is prudent to identify abnormalities contributing to the linked association between heart failure and retinopathy. At least, we should trigger evaluation of retinopathy in type 2 diabetes patients for further cardiac status. And further treatments targeted at the microvascular disease may ultimately decrease macrovascular disease risk as well and that might be greatly beneficial in the vast diabetic population. AIMS AND OBJECTIVES: 1. To compare LV function by ECHO in Type 2 Diabetes mellitus patients with and without retinopathy. 2. To look for possible association between severity of DR and severity of cardiac dysfunction by ECHO, independent of possible confounding factors. MATERIALS AND METHODOLOGY: Study Place: Department of General Medicine, Government Stanley Medical College & Hospital. Study Period: March 2012 to October 2012. Study Design: Nested Case Control Study. Sample size: 100 subjects. Inclusion Criteria: Type 2 Diabetes mellitus patients attending Government Stanley Medical College and Hospital as Op/Ip. Exclusion Criteria: 1. Previous history of cardiovascular disease. 2. Previous ocular diseases. 3. Concurrent medication with drugs altering cardiac dynamics. STATISTICAL ANALYSIS: Data were collected in a preformed proforma. Statistical analysis was done using SPSS version 11.0 for Windows. Categorical data were expressed as absolute counts and percentages. Continuous data were expressed as mean and standard deviation. For the variables in qualitative form, Chi square and Fisher’s exact test was used in univariate analysis and further multivariate logistic regression was utilised to observe the association between the study variables and outcome. A p value of less than 0.05 was considered significant. RESULTS: A total of 100 subjects were included in the study. There were a total of 47 male patients and 53 female patients. A total of 42 subjects were aged above 60 years, the median age was 55.50 years with 95% C.I. being 53.2 to 57.5 years. Sixty five patients (65%) had a duration of diabetes for more than five years. Fifty eight patients (58%) among the study subjects had poor glycemic control. Twenty four patients had comorbid hypertension, 39 patients had additional dyslipidemia. There were in total 18 subjects who gave history of smoking and 13 subjects with history of alcoholism. Two of the study subjects had cerebrovascular accident, 3 had diabetic foot, 1 had peripheral vascular disease, 10 patients had diabetic nephropathy. In addition, two patients had co-existing thyroid disorders. The incidence of diabetic retinopathy was 38% among the study population, and a total of 46% of study subjects had evidence of cardiac dysfunction. Twenty patients had systolic dysfunction, 43 patients had diastolic dysfunction and 17 patients had both. Thirty four of the study subjects with LV dysfunction (LVD) had coexistent diabetic retinopathy (74%). CONCLUSIONS: Type 2 Diabetes mellitus patients with diabetic retinopathy had significant association with impaired LV function detected by echocardiography in comparison to those without retinopathy. The severity of retinopathy in these patients correlated with grade of diastolic dysfunction. Diabetic patients who are detected with retinopathy should also be assessed for asymptomatic cardiac involvement. However, there must be studies with a larger sample size and follow up period to know the natural history of cardiac involvement in patients with type 2 diabetes mellitus and trials to study the benefit for cardiac screening in such individuals, before strong recommendations are made.