Coronary artery disease in Asians J. Rajadurai
A. Shatar
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
J. Arokiasamy
0. M e i L i n
Associate Professor, Department of Social and I’reventive Medicine, University Hospital, Kuala Lumpur, Malaysia.
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
K. Pasamanickam Associate Professor, Department of Social and Preventive Medicine, University Hospital, Kuala Lumpur, iMalaysia.
Abstract: From available studies, there appears to be a racial preponderance of coronary artery disease (CAD) among Indians when compared to other ethnic groups. We found that this racial difference exists even in a young Asian population with premature atherosclerosis. In this small series, these racial differences could not be explained by the commonly known risk factors for coronary artery disease - smoking, hypertension, diabetes and hypercholesterolaemia, findings similar to those found in older patients elsewhere. Only fasting triglyceride levels were significantly higher among young Indians compared to non Indians (p < 0.02) although the importance of this finding as a risk factor for CAD remains controversial. T h e majority of these young patients were treated medically and their one year survival was good. (Aust NZ J Med 1992; 22: 345-348;) Key words: Coronary artery disease, ethnic differences, premature atherosclerosis.
INTRODUCTION Coronary artery disease (CAD) is an important cause of morbidity and mortality in most countries. From available studies, there appears to be a racial preponderance of the disease in Indians when compared to Western or native populations.’.’ This trend is also apparent in a multiracial country like Malaysia. The proportion of Malays, Chinese and Indians constituting the population for the year 1988 were 58Y0, 32% and 10% while the proportion of medically certified deaths from CAD were 36Y0, 39% and 24% respectively.” T h e purpose of this study was to determine if this pattern of racial predominance was also evident in young patients with CAD. METHODS This is a retrospective study of patients 40 years and below admitted to the University Hospital, Kuala
Lumpur between 1984, when coronary angiograms were first performed in the institution, and May 1991. Criteria for selection included definite evidence of CAD i.e. classical symptoms associated with characteristic resting or stress electrocardiographic (ECG) changes. Patients who had typical or atypical symptoms but no ECG changes and patients with abnormal electrocardiograms but no symptoms were excluded. One hundred and five patients fulfilled these criteria but hospital records of 103 were available for analysis. Information relating to age, sex, race and clinical profile were noted. Patient records were reviewed to determine the presence of the following risk factors: 0 Smoking - this included all patients who were currently smoking; ex-smokers were excluded. 0 Hypertension - this was considered to be present if the patient was on antihypertensive therapy or if the ___~
Reprint requests ro: Dr Jeyarnalar Rajadurai, Department of Medicine, University Hospital, 59100 Kuala Lumpur, Malaysia. CORONARY ARTERY DISEASE
Aust NZ J Med 1992; 22
34 5
rAi3lE 1 Age Sex and Racial Distribution in Patients with Premature CAD Group 1 (CAD)
Group 2 (No CAD)
86 (95) 5 (5)
1 1 (92) 1 (8)
97 (94) 6 (6)
27 (30)
5 (42)
32 (31) 12 (12) 58 (56) 1 (1)
Malays
Sex
na'es fernales Ethnic distribution Malays Chinese Indians others Age 30 years and below 31 -35 years 36 40 years
12 (13) 51 (56) 1 (1)
10 (1 1 ) 25 (28) 56 (62)
-
7 (58) -
4 (33) -
8 (67)
TABLE 2 Risk Factors Among the Malays Chinese and Indians with Atherosclerotic Coronary Arteries
14 (14) 25 (24) 64 (62)
Number Age (years) Cholesterol (mmolll) Triglyceride (rnmol/L) Smoking Diabetes Hypertension Positive family history Body mass indices (kg/m')
Chinese
Indians
27 3521-36 6 4+1 6 1 9+ 1 1 72 (82) 3 (11) 9 (33) 8 (30)
12 51 36.3 3.7 35.6 2 4.0 7.1 k2.1 6.7+1.4
25 5 k 3 4
2 5 . 2 + 3 1 24 5 i 2 . 9
1.7*0.8
2 . 6 5 1.4
7 2 1 5
30 (59) 9 (18) 11 (22) 24 (47)
(58) (17) (80) (42)
NB The only patient belonging to other' races in the group with
alheroscierotic disease is not included in this analysis Figures In parentheses indicate percentage of total for each group
CAD =coronary artery disease
Figures in parentheses indicate percentages
diastolic blood pressure (BP) was consistently above 100 mniHg. U Diabetes - a patient was considered to be diabetic if he/she was on treatment or if the fasting blood sugar was above 8 mmol/L. 0 Family history of CAD in first degree relatives. 0 Lipid levels - the total blood cholesterol and triglyceride levels were noted in a venous sample after an overnight fast. T h e values considered in analysis were those taken at least a month after an infarct. None of our patients were on antilipid drug therapy. i, Body mass indices - these were calculated from weight (kg.)/heightz (m') at the time of hospital stay. All patients underwent selective coronary arteriography and left ventricular angiography. Based on the coronary anatomy, patients were divided into two groups. Group 1 consisted of patients with atherosclerotic disease which was defined as sharp edged, plaque like or irregular indentations into the vessel lumen. Group 2 patients had angiographically normal coronary arteries. There were no patients with coronary artery anomalies.
Statistical Analysis Results are expressed as mean k SD. The significance of any differences in quantitative variables between the three races were analysed by the one way test of variance. If there was significance at F < 0.05, then the unpaired Student t test was applied. T h e difference between proportions was assessed by the Chi-square with Yates' correction for a 2 x 2 contingency tables.
or below. There was no significant difference in the age of presentation between the three races in Group 1 (Table 2).
Ethnic Distribution The racial distribution of Malays, Chinese and Indians in this population of premature CAD was 31%, 12% and 56% respectively. During this same period, the racial distribution for admissions to medical wards in the hospital were Malays 25.4%, Chinese 46.9% and Indians 27.7%. These indicate a preponderance of Indians with premature CAD. Risk Factor Analysis (Tables 2, 3) Group 1 L $id Levels The Chinese tended to have higher mean serum cholesterol levels (7.1 f 2.1 mmol/L) compared to the other races although these differences were not significant. Serum triglyceride levels were elevated in young Indians compared to non Indians (p< 0.02).
TABLE 3 Comparison of Risk Factors between Indians vs Non Indians n ti-e Group with Atherosclerotic Disease Indians Number Age (years) Cholesterol irnmoliL\ Triglyceride ~mmol/L) Smokina Diabetes Hypertension Positive family history
51
35 6 + 4 0 6 7+ 1 4 2 6; 1 4 30 (59)
Non Indians Significance
40 35 6 + 3 6 6 6+1 8 1 8: 1 0 30 (75) 5 (13) 10 (25)
NS
NS p
A. Shatar
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
J. Arokiasamy
0. M e i L i n
Associate Professor, Department of Social and I’reventive Medicine, University Hospital, Kuala Lumpur, Malaysia.
Lecturer, Department of Medicine, University Hospital, Kuala Lumpur, Malaysia.
K. Pasamanickam Associate Professor, Department of Social and Preventive Medicine, University Hospital, Kuala Lumpur, iMalaysia.
Abstract: From available studies, there appears to be a racial preponderance of coronary artery disease (CAD) among Indians when compared to other ethnic groups. We found that this racial difference exists even in a young Asian population with premature atherosclerosis. In this small series, these racial differences could not be explained by the commonly known risk factors for coronary artery disease - smoking, hypertension, diabetes and hypercholesterolaemia, findings similar to those found in older patients elsewhere. Only fasting triglyceride levels were significantly higher among young Indians compared to non Indians (p < 0.02) although the importance of this finding as a risk factor for CAD remains controversial. T h e majority of these young patients were treated medically and their one year survival was good. (Aust NZ J Med 1992; 22: 345-348;) Key words: Coronary artery disease, ethnic differences, premature atherosclerosis.
INTRODUCTION Coronary artery disease (CAD) is an important cause of morbidity and mortality in most countries. From available studies, there appears to be a racial preponderance of the disease in Indians when compared to Western or native populations.’.’ This trend is also apparent in a multiracial country like Malaysia. The proportion of Malays, Chinese and Indians constituting the population for the year 1988 were 58Y0, 32% and 10% while the proportion of medically certified deaths from CAD were 36Y0, 39% and 24% respectively.” T h e purpose of this study was to determine if this pattern of racial predominance was also evident in young patients with CAD. METHODS This is a retrospective study of patients 40 years and below admitted to the University Hospital, Kuala
Lumpur between 1984, when coronary angiograms were first performed in the institution, and May 1991. Criteria for selection included definite evidence of CAD i.e. classical symptoms associated with characteristic resting or stress electrocardiographic (ECG) changes. Patients who had typical or atypical symptoms but no ECG changes and patients with abnormal electrocardiograms but no symptoms were excluded. One hundred and five patients fulfilled these criteria but hospital records of 103 were available for analysis. Information relating to age, sex, race and clinical profile were noted. Patient records were reviewed to determine the presence of the following risk factors: 0 Smoking - this included all patients who were currently smoking; ex-smokers were excluded. 0 Hypertension - this was considered to be present if the patient was on antihypertensive therapy or if the ___~
Reprint requests ro: Dr Jeyarnalar Rajadurai, Department of Medicine, University Hospital, 59100 Kuala Lumpur, Malaysia. CORONARY ARTERY DISEASE
Aust NZ J Med 1992; 22
34 5
rAi3lE 1 Age Sex and Racial Distribution in Patients with Premature CAD Group 1 (CAD)
Group 2 (No CAD)
86 (95) 5 (5)
1 1 (92) 1 (8)
97 (94) 6 (6)
27 (30)
5 (42)
32 (31) 12 (12) 58 (56) 1 (1)
Malays
Sex
na'es fernales Ethnic distribution Malays Chinese Indians others Age 30 years and below 31 -35 years 36 40 years
12 (13) 51 (56) 1 (1)
10 (1 1 ) 25 (28) 56 (62)
-
7 (58) -
4 (33) -
8 (67)
TABLE 2 Risk Factors Among the Malays Chinese and Indians with Atherosclerotic Coronary Arteries
14 (14) 25 (24) 64 (62)
Number Age (years) Cholesterol (mmolll) Triglyceride (rnmol/L) Smoking Diabetes Hypertension Positive family history Body mass indices (kg/m')
Chinese
Indians
27 3521-36 6 4+1 6 1 9+ 1 1 72 (82) 3 (11) 9 (33) 8 (30)
12 51 36.3 3.7 35.6 2 4.0 7.1 k2.1 6.7+1.4
25 5 k 3 4
2 5 . 2 + 3 1 24 5 i 2 . 9
1.7*0.8
2 . 6 5 1.4
7 2 1 5
30 (59) 9 (18) 11 (22) 24 (47)
(58) (17) (80) (42)
NB The only patient belonging to other' races in the group with
alheroscierotic disease is not included in this analysis Figures In parentheses indicate percentage of total for each group
CAD =coronary artery disease
Figures in parentheses indicate percentages
diastolic blood pressure (BP) was consistently above 100 mniHg. U Diabetes - a patient was considered to be diabetic if he/she was on treatment or if the fasting blood sugar was above 8 mmol/L. 0 Family history of CAD in first degree relatives. 0 Lipid levels - the total blood cholesterol and triglyceride levels were noted in a venous sample after an overnight fast. T h e values considered in analysis were those taken at least a month after an infarct. None of our patients were on antilipid drug therapy. i, Body mass indices - these were calculated from weight (kg.)/heightz (m') at the time of hospital stay. All patients underwent selective coronary arteriography and left ventricular angiography. Based on the coronary anatomy, patients were divided into two groups. Group 1 consisted of patients with atherosclerotic disease which was defined as sharp edged, plaque like or irregular indentations into the vessel lumen. Group 2 patients had angiographically normal coronary arteries. There were no patients with coronary artery anomalies.
Statistical Analysis Results are expressed as mean k SD. The significance of any differences in quantitative variables between the three races were analysed by the one way test of variance. If there was significance at F < 0.05, then the unpaired Student t test was applied. T h e difference between proportions was assessed by the Chi-square with Yates' correction for a 2 x 2 contingency tables.
or below. There was no significant difference in the age of presentation between the three races in Group 1 (Table 2).
Ethnic Distribution The racial distribution of Malays, Chinese and Indians in this population of premature CAD was 31%, 12% and 56% respectively. During this same period, the racial distribution for admissions to medical wards in the hospital were Malays 25.4%, Chinese 46.9% and Indians 27.7%. These indicate a preponderance of Indians with premature CAD. Risk Factor Analysis (Tables 2, 3) Group 1 L $id Levels The Chinese tended to have higher mean serum cholesterol levels (7.1 f 2.1 mmol/L) compared to the other races although these differences were not significant. Serum triglyceride levels were elevated in young Indians compared to non Indians (p< 0.02).
TABLE 3 Comparison of Risk Factors between Indians vs Non Indians n ti-e Group with Atherosclerotic Disease Indians Number Age (years) Cholesterol irnmoliL\ Triglyceride ~mmol/L) Smokina Diabetes Hypertension Positive family history
51
35 6 + 4 0 6 7+ 1 4 2 6; 1 4 30 (59)
Non Indians Significance
40 35 6 + 3 6 6 6+1 8 1 8: 1 0 30 (75) 5 (13) 10 (25)
NS
NS p
