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 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 11  |  Issue : 1  |  Page : 13-17

Screening modalities for an asymptomatic cardiovascular disease in type 2 diabetics mellitus patients


1 Department of Pharmacology, AMC-MET Medical College, Ahmedabad, Gujarat, India
2 NHL Municipal Medical College, Ahmedabad, Gujarat, India
3 DiaCare - Diabetes Care and Hormone Clinic, Ahmedabad, Gujarat, India

Date of Web Publication7-Apr-2014

Correspondence Address:
Bhavesh M Vyas
Department of Pharmacology, AMC-MET Medical College, Ahmedabad, Gujarat
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0189-7969.130045

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  Abstract 

Background: Asymptomatic myocardial ischemia is more common in diabetic than in the normal individual. Therefore, it becomes necessary to screen cardiovascular disease as early as possible.
Objective: The present study was aimed to assess non-invasive procedures for the detection of asymptomatic myocardial ischemia and other coexistent risk factors in type 2 diabetics.
Methods: A total of 76 patients with type 2 diabetes mellitus (T2DM) with no clinical history of coronary heart disease were included in the study and evaluated for silent myocardial ischemia by stress cardiac exercise tolerance test (ETT), echocardiography and electrocardiogram (ECG). Baseline clinical characteristic such as age, gender, Smoking, duration of diabetes, hemoglobin A1C (HbA1c) %, urinary microalbuminuria, hypertension, dyslipidemia and retinopathy were evaluated and reported. The clinical characteristic of ischemic ETT and normal ETT patients were compared.
Results: The ETT showed an ischemic pattern in 22 patients (28.94%), the ECG was suggestive of ischemia in six patients (7.89%), echocardiography showed diastolic dysfunction in 18 (23.68%). Patients with microalbuminuria, hypertension, dyslipidemia and smoking and/or diastolic dysfunction were more prone than others to have ischemic ETT and patients with diastolic dysfunction had a higher prevalence of ischemic ETT. The prevalence of microalbuminuria, hypertension, dyslipidemia and smoking were found significantly higher in ischemic ETT when compared to normal ETT patients. The body mass index, HbA1c% and duration of diabetes were not shown significant deference in patients with positive ischemic ETT when compared to normal ischemic ETT patients.
Conclusion: The cardiac ETT was found to be most helpful for detecting asymptomatic myocardial ischemia in T2DM patients on outpatient department basis. Study provides evidence for prevalence of asymptomatic myocardial infarction (MI) in diabetic patients. Moreover, this study will help to other diabetes care center for screening and prevention of asymptomatic MI in T2DM patients.

Keywords: Cardiovascular diseases, diabetes, electrocardiogram, exercise tolerance test, hemoglobin A1C, myocardial infarction


How to cite this article:
Vyas BM, Vyas CK, Saboo BD. Screening modalities for an asymptomatic cardiovascular disease in type 2 diabetics mellitus patients. Nig J Cardiol 2014;11:13-7

How to cite this URL:
Vyas BM, Vyas CK, Saboo BD. Screening modalities for an asymptomatic cardiovascular disease in type 2 diabetics mellitus patients. Nig J Cardiol [serial online] 2014 [cited 2020 Aug 13];11:13-7. Available from: http://www.nigjcardiol.org/text.asp?2014/11/1/13/130045


  Introduction Top


Diabetes mellitus (DM) is a chronic metabolic disorder of carbohydrate, protein and lipid metabolism. It is the 3 rd biggest disease in world [1] and characterized by persistent hyperglycemia and needs careful management by using drugs, diet control and mild exercise for the rest of the lifetime. [2],[3]

Coronary heart disease (CHD) develops in type 2 diabetes mellitus (T2DM), [4] and patients with T2DM who have not had a myocardial infarction (MI) have a risk of infarction similar to that among non-diabetic patients who have had a prior MI. [5] Cardiovascular diseases (CVD), comprising CHD and cerebro-vascular diseases, are currently the leading cause of death globally, accounting for 21.9% of total deaths and are projected to increase to 26.3% by 2030. The factors that coalesce to increase the risk of developing atherosclerotic CHD were demonstrated in Framingham in the mid-20 th century and have subsequently been shown to be pervasive across ethnicities and regions of the world. These are not new risks, but the ubiquity of smoking, dyslipidemia, obesity, diabetes and hypertension has been gradually escalating and is thought to be the driving force behind the epidemic of heart disease faced today. Of the risk factors (RFs), diabetes and its predominant form, T2DM, has a distinctive association with CHD. Those with diabetes have two to four fold higher risk of CHD than people without diabetes and CVD accounts for 65-75% of deaths in people with diabetes. [6],[7],[8]

Therefore, it becomes a priority to detect CHD as early as possible in diabetics patient, with the need for complete coronary screening. Coronary angiography is highly sensitive and very specific diagnosis test for coronary artery disease. The coronary angiography is an expensive and invasive screening procedure so we can start screening of coronary artery disease with affordable and non-invasive cardiac screening procedure before the recommendation of invasive screening procedure. Hence it becomes necessary to develop a non-invasive cardiac screening test that should be inexpensive, readily available and has specificity and an acceptable sensitivity. However, electrocardiogram (ECG) and the exercise tolerance test (ETT) fall into this category. They are widely available, reasonably safe, relatively inexpensive and more importantly, of an acceptable sensitivity and specificity. [9],[10],[11] The aim of this study was to assess and use non-invasive procedures for the detection of asymptomatic myocardial ischemia and other coexistent RFs such as microalbuminuria, hypertension, dyslipidemia, retinopathy and smoking habit in patients with T2DM.


  Materials and Methods Top


In this study, 76 T2DM patients (Male [n = 40] and Female [n = 36]) who have attended the diabetic out-patient clinic at DiaCare Clinic, Ahmedabad, India between February 2010 and January 2013 were included. The mean duration of the DM was 10.19 ± 5.75. The criteria for inclusion in this study were: T2DM patients, age <70 years, hemoglobin A1C (HbA1c) >8%, patients under the same treatment since last 3 months, no clinical history (past or present) suggestive of myocardial ischemia and no current foot ulcer or other condition that could prevent the patient from performing a cardiac stress test. The criteria for exclusion in the present study were: Type 1 diabetes patients, age >70 years, HbA1c <8%, pregnant women, critically ill or recently operated patients, not willing to give informed consent, clinical history (past or present) suggestive of myocardial ischemia and foot ulcer or other condition that could prevent the patient from performing a cardiac stress test. Baseline epidemiological parameters such as age, gender, body mass index (BMI), duration of diabetes, HbA1c%, urinary microalbuminuria, hypertension, dyslipidemia and smoking habit were included in the study. We primarily examined cardiac ETT profile and compared it to other commonly used, non-invasive cardiac testing methods: ECG and echocardiography. The study was approved by the ethics committee of the hospital and duly signed informed consent were taken from all the patients.

Transthoracic echocardiography

An ATL HDI 3000 CV machine using a 2.5-MHz transducer was used to perform two-dimensional and Doppler echocardiography examinations. Both the examinations were performed in the left lateral supine position. Pulsed-wave Doppler studies of the left ventricle filling were performed using the apical four-chamber view, with the sample volume positioned at the mitral leaflet tips, adjusted to produce maximal possible transmittal velocities using both the audible signal and the spectral velocity display. An ECG was displayed simultaneously. Peak late diastolic flow velocity, peak early diastolic flow velocity (E) due to atrial contraction (A), ratio between peak late and peak early flow velocities (E/A ratio), acceleration and duration of A wave and deceleration times of early diastolic velocity were measured. By placing the sample volume (0.5-1 cm) in the right superior pulmonary vein in apical four-chamber view, pulmonary venous velocities were obtained. Peak diastolic velocity (D), peak systolic (S) during ventricular systole, duration of reversal of flow (R) associated with atrial contraction (A) and peak velocity and the difference between pulmonary reversal wave and the duration of the mitral A wave were noted. Continuous wave Doppler at an intermediate position between inflow and outflow to record both velocities. Isovolumic relaxation time, interval between the end of ejection and onset of mitral inflow, was measured using continuous wave Doppler at an intermediate position between inflow and outflow. After the reading of left ventricular relaxation pattern, the diagnosis for diastolic dysfunction was made.

Cardiac ETT

As per Bruce protocol patients performed a treadmill stress test in accordance. During exercise and into recovery various majors related to the heart are recorded continuously at baseline, during exercise and into recovery, such as heart rate, blood pressure (BP) and ECG. ST segment deviation was measured 80 ms after J point. Treadmill stress test was stopped when the patient developed ST or angina pectoris or QRS changes occurred.

Data analysis

SPSS for Windows (Version 10; SPSS, Chicago, IL, USA) was used for data management and statistical analysis. Using the Student's t-test, means were compared and percentages were compared with the Chi-square test. Differences with P < 0.05 were considered to be significant.


  Results Top


A total of 76 patients were selected for the present study in Gujrat. Baseline clinical characteristics of the subjects are given in the [Table 1]. At the time of the study, no patient had clinical symptoms or signs of myocardial ischemia. However, major RFs related to ischemic heart disease in T2DM were measured and prevalence of dyslipidemia, smoking and systemic hypertension was founded in 52.63%, 43.42% and 61.84% in the study population, respectively. The prevalence retinopathy was found in 52.63% of the study population. Microalbuminuria >123.18 ± 69.35 mg/l was seen in 40.5% of the patients and found to be significantly associated with ischemic ETT (P = 0.03).
Table 1: Baseline clinical characteristic of participants

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Further analysis of the major RFs showed that out of total 76 patient 11.84% of the patients had no RFs for ischemic heart disease other than T2DM, 31.57% had one additional RF, another 32.89% had two additional RFs and 23.68% had three additional RFs. Obesity was prevalent and BMI was 29.66 ± 2.29 kg/m 2 .

Totally 52 cardiac abnormalities exposed by using the three non-invasive techniques are shown in [Table 2]. Of these, ETT showed an ischemic pattern in 22 patients (28.94%) and transthoracic echocardiography showed diastolic dysfunction in 18 patients (23.68%), all of which were reversible. Only six patients (7.89%) had shown a pattern suggestive of ischemia on resting ECG.
Table 2: Non-invasive cardiac test for the detection of abnormalities (diastolic dysfunction and ischemia by echocardiography)

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Of the 22 patients with an ischemic pattern on ETT, nine cases showed diastolic dysfunction on echocardiography and three had a pattern suggestive of ischemia on resting ECG. However, ETT missed nine cases of myocardial dysfunction that were seen using the other techniques: Echocardiography 6 and ECG 3.

The prevalence of hypertension (81.81% vs. 53.7%, P < 0.03), dyslipidemia (72.2% vs. 44.44%, P < 0.04), miroalbuminuria (148.13 ± 72.38 vs. 113.01 ± 66.06 μg/l, P < 0.03) and smoking habit (63.6% vs. 35.18%, P < 0.03) were found significantly higher in diabetic patients with positive ETT when compared to diabetic patients with normal [Table 3]. Diastolic dysfunction was found to be more prevalent in ischemic patients than in normal patients (46.7% vs. 11.62%). Patients over 55 years of age were more likely than normal subjects to have an ischemic pattern on ETT and diastolic dysfunction on echocardiography.
Table 3: Clinical characteristic of patients with ischemia and normal ETT

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  Discussion Top


Diabetes is a chronic illness that requires continuing medical care and patient self-management education to prevent acute complications and to reduce the risk of long-term complications. Diabetes care is complex and requires that many issues, beyond glycemic control, be addressed. The National Urban Diabetes Survey in India has shown standardized prevalence of diabetes and impaired glucose tolerance (IGT) to be 12.4% and 14% respectively with no gender difference. Subjects under 40 years of age had a higher prevalence of IGT than diabetes (12.8% vs. 4.6%: P < 0.001). Hence, India has garnered the notoriety of being the diabetic capital of the world. [12] Diabetics are prone to develop secondary complications like diabetics are prone to develop secondary complications like nephropathy, [13] ketoacidosis, [14] neuropathy, [15] retinopathy, [16] atherosclerosis [17] and cardiovascular problems. [4],[18] Occurrence of myocardial ischemia is more frequently in diabetics than in non-diabetics. MI is a major complication that is encountered in progressive course of DM. [19],[20] Hence it becomes necessary to screen diabetes routinely for these secondary complication, but very little is done for silent myocardial ischemia, a complication which could be a terminal event in its first clinical presentation. [21],[22]

Heart disease, especially CHD is a major cause of mortality and morbidity among patients with T2DM. [23] When compared to individuals without T2DM, those with T2DM have a higher prevalence of CHD, a greater extent of coronary ischemia and are more likely to have a MI. Diabetes is a major cardiovascular RF with hypertension, smoking, dyslipidemia, hypercholesterolemia and left ventricular hypertrophy. The Framingham Heart Study and the Multiple Risk Factor Intervention Trial (MRFIT) illustrate the relationship between diabetes and CHD. [24],[25] Framingham study suggest the presence of diabetes doubled the age-adjusted risk for CVD in men and tripled it in women. [19] Similar results were suggested by MRFIT. Numerous factors such as hypertension, smoking, dyslipidemia, contribute as RF in diabetes. Epidemiology analysis findings show that BP >120/80 mm of Hg are associated with increased CVD rate and mortality in individual with diabetes. [26] Smoking is the most common RF followed by dyslipidemia, hypertension and obesity.

In the present study myocardial dysfunctions was found in 52 patients. However, there is no single test available that can detect all of the dysfunctions, ETT proven as a most useful test, followed by echocardiography and ECG. Although the most helpful was ETT, it failed to detect cardiac abnormalities in nine patients, which give an indication for the need to use additional techniques that can help to detect cardiac abnormalities in the maximum number of patient, particularly when ETT findings are equivocal. In such cases, we suggest to perform echocardiography. In this study, some of the patients were ischemic by ETT but none were symptomatic, reflecting that the high prevalence of silent MI among diabetics.

In our study, the presence of myocardial ischemia was highly associated with the presence of microalbuminuria (P < 0.05), hypertension (P < 0.03), dyslipidemia (P < 0.04) and smoking (P < 0.03) consistent with others findings. [26],[27],[28],[29] Since microalbuminuria without overt nephropathy is associated with a high cardiovascular mortality rate, cardiac stress testing is recommended. [29],[30] The real challenge is to decide the best non invasive cardiac test in asymptomatic patients with T2DM, rather than to investigate the T2DM patients who have angina pectoris or even the angina equivalent (exertional dyspnea, giddiness). The greatest number of cases of myocardial ischemia were revealed by ETT (n = 22) [Table 3] in the present study. Since diastolic dysfunction is common in diabetic patient, echocardiography may be indicated for detecting silent MI among diabetic patients, [28],[31] was found in 46.7% of patients with ischemic ETT, significantly more frequently than in normal patients (11.62%). ECG being the least expensive followed by echocardiography, then ETT, with myocardial perfusion. ETT has been proven to be more helpful technique than any other testing method and is one of the least expensive tools. It seems that ETT can be used as the non-invasive cardiac testing technique when investigating asymptomatic diabetics for different cardiac abnormalities such as MI. [29]


  Conclusion Top


According to results it may be concluded that the cardiac ETT test was most helpful non-invasive technique for detecting asymptomatic MI in type 2 diabetics. For those with equivocal ETT findings, echocardiography is recommended. The prevalence of asymptomatic myocardial ischaemia in the type 2 diabetics were higher, therefore regular screening is suggested to avoid cardiac complications. Moreover, this study will help to other diabetes care center for screening of asymptomatic MI in type 2 diabetics.

 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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