Adv. Cardiol., vol. 18, pp. 113-121 (Karger, Basel 1976)
Occupational Physical Activity and Coronary Artery Disease A Clinicopathologic Appraisal
V. RISSANEN Department of Forensic Medicine, University of Helsinki, Helsinki, and Department of Medicine, University of Kuopio, Kuopio
1. Introduction
Epidemiological evidence suggests that sedentary living contributes to the increased risk of atherosclerotic diseases [1, 2, 4]. The risk seems to be associated particularly with deaths occurring suddenly or after myocardial infarction. One interpretation of epidemiological and patho-anatomic studies has been that the association between sedentary living and the increased mortality rate of ischaemic heart disease (IHD) might be better explained on the basis of a different myocardial response to atherosclerotic coronary occlusion than on the basis of a premature accelerated development of atherosclerosis [1,2]. No uniform agreement exists, however, on the validity of this hypothesis. In the present study, the association between occupational physical activity and coronary artery disease was studied in a series of male violent deaths and in two series of sudden deaths from IHD.
The severity of coronary atherosclerosis was studied in a series of 172 men aged 25 years or over who died of violent causes - accidents, suicides or homicides [9]. The men were subdivided into three groups according to the physical activity required by their occupation. Occupations classified as 'sedentary' are those in which work is done mainly sitting. The group of
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II. Coronary Atherosclerosis in Relation to Occupational Physical Activity in Male Violent Deaths
114
RISSANEN
o
_
Fatty streak Raised lesion
11
8
14 11
15
25-34
16
9
35- 44
SMA
SMA
45 - 54
55 - 64
S
M
65 -
'moderate activity' includes occupations in which work is done standing, and also includes walking. 'Active' occupations are those in which the employee mainly walks, or in which the work demands heavy physical exertion, e. g. carrying heavy objects, etc. 60 men in the series were classified as 'sedentary' (35%), 68 men as 'moderately active' (39%) and 44 men as 'active' (26%). The estimation of the severity of coronary atherosclerosis was made from specimens of longitudinally opened coronary arteries by applying the point-counting technique to the measurement of the extent of atherosclerotic lesions, fatty streaks and raised lesions. The extent of calcifications was assessed by point-counting from radiographs of arterial specimens. The methods of the study have been described in detail in previous papers [6, 7]. The extent of coronary fatty streaks and raised lesions tended to be smallest in 'active' men while the 'sedentary' and 'moderately active' men did not differ in this respect (fig. 1). The difference between 'sedentary' and 'moderately active' men with regard to the physical activity demanded by their jobs was obviously rather small. When these two groups were combined, a significant difference was found in the extent of coronary raised lesions and calcifications (p < 0.05) between the combined group and the group of active men (fig. 2).
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
Fig. 1. Mean values for the absolute area of coronary fatty streaks and raised lesions (cm2) in 'sedentary' (S), 'moderately active' (M) and 'active' (A) men in the series of violent deaths.
Physical Activity and Coronary Artery Disease
115
cm2
2Ir'---------=~ ~[brn[b Calcificat ion
9
8
Raised
lesion
7
6 5 4
3
2
5 4
Fatty streak
3
9
2
31
16 25
8
26
6
\I
30
25-34
SM A
SM A
SM A
35-44
45-54
55-64
SM A
65-
It is, of course, possible that the occurrence of coronary atherosclerosis in the present 'active' men as compared with others was a reflection of a difference between groups other than that determined by physical activity. No confounding factors could, however, be identified between the groups. The following risk indicators were able to be clarified in the series: a history of hypertension, diabetes or clinical heart disease, and an autopsy finding of an old myocardial infarction [9]. The overall prevalence of these factors was 18% in 'sedentary' men, 13% in 'moderately active' men and 16% in 'active' men. The men in the three groups did not differ with regard to nutritional status as indicated by the ratio of the body weight to the square of the height or with regard to heart weight [9]. The present finding suggests that a persistently physically active life might retard the development of coronary atherosclerosis. On the basis of this
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
Fig. 2. Mean values for the absolute area of coronary fatty streaks, raised lesions and calcifications (cm2) in the combined group of 'sedentary' and 'moderately active' men (SM) and in the 'active' men (A) in the series of violent deaths.
116
RrSSANEN
hypothesis, it can be expected that in the population of physically active men coronary atherosclerosis reaches the threshold level of severity necessary for the development of clinical IHD relatively less often than in sedentary men.
III. Extent of Coronary Atherosclerosis in Relation to Occupational Physical Activity in a Series of IHD Deaths The extent of coronary atherosclerosis was assessed by applying the point-counting technique in a series of 109 men aged 35-64 years whose cause of death was classified as IHD on the basis of a routine medico-legal autopsy in the Department of Forensic Medicine, University of Helsinki. In 79 cases, death occurred within 24 h of the onset of the fatal attack, and in the remaining 30 cases, death was unwitnessed. A recent myocardial infarction was found at autopsy in 51 cases. On the basis of occupation, 47 men (43%) were classified as 'sedentary', 49 men (45%) as 'moderately active' and 13 men (12%) as 'active'. The median age in 'sedentary' men was 53 years, in 'moderately active' men 57 years and in 'active' men 53 years. In the series of IHD deaths, no differences were found in the mean extent of coronary raised lesions or calcifications between the 'sedentary', 'moderately active' and 'active' men (fig. 3).
cm 2
~~:{::(:l~ I 11
Calc.
47
10
9 8 7 6 5 4
Raised lesion
Fig. 3. Mean values for the absolute area of coronary raised lesions and calcifications (cm2) in 'sedentary' (S), 'moderately active' (M) and 'active' (A) men in the series of IHD deaths.
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
3 2
Physical Activity and Coronary Artery Disease
117
Clinicopathologic correlations with occupational physical activity were studied in a series of 112 witnessed sudden deaths occurring within 24 h of the onset of the fatal attack. The series was collected from medico-legally autopsied sudden deaths occuring in Helsinki during a period of 12 months. A special methodology was applied at autopsy to the study of the heart; a double contrast coronary angiography was used in the estimation of coronary stenosis [5], and macroscopic histochemistry and histology in the detection of recent myocardial infarction [8, 11]. Information on previous diseases was obtained by the interviewers from the relatives of the patients and from hospital records in association with the study of the Ischaemic Heart Disease Register of Helsinki [8, 10]. On the basis of occupation, 54 men (49%) were classified as 'sedentary', 43 (38%) as 'moderately active' and 15 (13%) as 'active'. In 'sedentary' men, the median age was 57, with an age range from 39 to 65 years, in 'moderately active' men 59, with a range from 31 to 65 years and in 'active' men 57, with a range from 38 to 65 years. The disease history was available for 14 of 15 'active' men. Twelve of them (86%) had suffered from angina pectoris or had a history of myocardial infarction. The remaining two men had a history of an atherosclerotic disease, one a claudication, the other a cerebro-vascular accident. In 'sedentary' men, the prevalence of a previous angina or myocardial infarction was 55%, and in 'moderately active' men 68%. The difference between the 'sedentary' and 'active' men with regard to the history of clinical IHD was significant (the hypergeometric distribution test; p < 0.05). A history of claudication was known in four 'sedentary' men without histories of previous clinicalIHD. No significant differences were found between 'sedentary', 'moderately active' and 'active' men in the occurrence of premonitory symptoms, in the prevalence of a recent or old myocardial infarction obtained at autopsy or in the prevalence of a coronary occlusion or thrombosis (table I). The severity of the occlusive coronary artery disease was estimated using a simple score method. The right coronary artery, left anterior descending coronary artery and left circumflex coronary artery were classified as follows: score 0 = no stenosis or less than half stenosis; score 1 = half stenosis but no occlusion; score 2 = occlusion. The scores for the three main coronary trunks were added up to give a stenosis score for the coronary
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
IV. Disease History and Cardiac Pathology in Relation to Occupational Physical Activity in a Series of Sudden Deaths
RISSANEN
118
Table [. Prevalence of previous symptomatic heart disease, hypertension; premonitory symptoms and autopsy findings of the heart in sedentary, moderately active and active men in the series of sudden deaths
Angina pectoris Myocardial infarction Hypertension Premonitory symptoms Recent myocardial infarction Old myocardial infarction Coronary occlusion Coronary thrombosis
Sedentary men (54 cases)
Moderately active men (43 cases)
Active men (15 cases)
data number % available
data number % available
data number available
~~
49 52 50 49
25 16 15 29
51 31 30 59
40 39 38 40
27 13 13 25
67 33 34 63
13 13 14 11
11 5 1 7
85 38 7 64
54
40
74
43
30
70
15
13
87
54 54 54
35 43 25
65 80 46
43 43 43
32 34 20
74 79 47
15 15 15
10 11 8
67 73 53
arterial tree. The range of this score was thus from 0 to 6. Low stenosis scores from 0 to 3 were more common in 'sedentary' (46%) and 'moderately active' men (40%) than in 'active' men (27%) (fig. 4). The difference between 'sedentary' and 'active' men was not statistically significant in this respect. A single or double vessel disease in coronaries was found in 50% of 'sedentary' men, but in only 20% of 'active' men (the hypergeometric distribution test; p < 0.05). A marked hypertrophy of the heart was much more common in 'sedentary' and 'moderately active' men than in 'active' men (fig. 5). Obviously, this difference was in part but not totally explained by differences in the prevalence of hypertension between groups (table I, fig. 5). The difference between 'sedentary' and 'active' men with regard to the heart weight was significant even though 'hypertensives' were excluded (the Wilcoxon test; p < 0.02).
Conclusions
Many methodological problems are encountered in a study of the present type. The selective composition of postmortem series and the retro-
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
v.
Physical Activity and Coronary Artery Disease
119
No of cases
5[ Active
tOr
L-~0--~--~;~--~--~4--~5~~A~15
Moderately active
10
o
6
4
::f
2°f S,edeo,."
. .
o
5
6
score
Fig. 4. Distribution of 'sedentary', 'moderately active' and 'active' men into groups according to the severity of the occlusive coronary artery disease (score) in the series of sudden deaths (see text for definitions).
HW 9 900
Moderately active
Sedentary
800
Active
~
700 600
a
~
-------"------.t
Occupational Physical Activity and Coronary Artery Disease A Clinicopathologic Appraisal
V. RISSANEN Department of Forensic Medicine, University of Helsinki, Helsinki, and Department of Medicine, University of Kuopio, Kuopio
1. Introduction
Epidemiological evidence suggests that sedentary living contributes to the increased risk of atherosclerotic diseases [1, 2, 4]. The risk seems to be associated particularly with deaths occurring suddenly or after myocardial infarction. One interpretation of epidemiological and patho-anatomic studies has been that the association between sedentary living and the increased mortality rate of ischaemic heart disease (IHD) might be better explained on the basis of a different myocardial response to atherosclerotic coronary occlusion than on the basis of a premature accelerated development of atherosclerosis [1,2]. No uniform agreement exists, however, on the validity of this hypothesis. In the present study, the association between occupational physical activity and coronary artery disease was studied in a series of male violent deaths and in two series of sudden deaths from IHD.
The severity of coronary atherosclerosis was studied in a series of 172 men aged 25 years or over who died of violent causes - accidents, suicides or homicides [9]. The men were subdivided into three groups according to the physical activity required by their occupation. Occupations classified as 'sedentary' are those in which work is done mainly sitting. The group of
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
II. Coronary Atherosclerosis in Relation to Occupational Physical Activity in Male Violent Deaths
114
RISSANEN
o
_
Fatty streak Raised lesion
11
8
14 11
15
25-34
16
9
35- 44
SMA
SMA
45 - 54
55 - 64
S
M
65 -
'moderate activity' includes occupations in which work is done standing, and also includes walking. 'Active' occupations are those in which the employee mainly walks, or in which the work demands heavy physical exertion, e. g. carrying heavy objects, etc. 60 men in the series were classified as 'sedentary' (35%), 68 men as 'moderately active' (39%) and 44 men as 'active' (26%). The estimation of the severity of coronary atherosclerosis was made from specimens of longitudinally opened coronary arteries by applying the point-counting technique to the measurement of the extent of atherosclerotic lesions, fatty streaks and raised lesions. The extent of calcifications was assessed by point-counting from radiographs of arterial specimens. The methods of the study have been described in detail in previous papers [6, 7]. The extent of coronary fatty streaks and raised lesions tended to be smallest in 'active' men while the 'sedentary' and 'moderately active' men did not differ in this respect (fig. 1). The difference between 'sedentary' and 'moderately active' men with regard to the physical activity demanded by their jobs was obviously rather small. When these two groups were combined, a significant difference was found in the extent of coronary raised lesions and calcifications (p < 0.05) between the combined group and the group of active men (fig. 2).
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
Fig. 1. Mean values for the absolute area of coronary fatty streaks and raised lesions (cm2) in 'sedentary' (S), 'moderately active' (M) and 'active' (A) men in the series of violent deaths.
Physical Activity and Coronary Artery Disease
115
cm2
2Ir'---------=~ ~[brn[b Calcificat ion
9
8
Raised
lesion
7
6 5 4
3
2
5 4
Fatty streak
3
9
2
31
16 25
8
26
6
\I
30
25-34
SM A
SM A
SM A
35-44
45-54
55-64
SM A
65-
It is, of course, possible that the occurrence of coronary atherosclerosis in the present 'active' men as compared with others was a reflection of a difference between groups other than that determined by physical activity. No confounding factors could, however, be identified between the groups. The following risk indicators were able to be clarified in the series: a history of hypertension, diabetes or clinical heart disease, and an autopsy finding of an old myocardial infarction [9]. The overall prevalence of these factors was 18% in 'sedentary' men, 13% in 'moderately active' men and 16% in 'active' men. The men in the three groups did not differ with regard to nutritional status as indicated by the ratio of the body weight to the square of the height or with regard to heart weight [9]. The present finding suggests that a persistently physically active life might retard the development of coronary atherosclerosis. On the basis of this
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
Fig. 2. Mean values for the absolute area of coronary fatty streaks, raised lesions and calcifications (cm2) in the combined group of 'sedentary' and 'moderately active' men (SM) and in the 'active' men (A) in the series of violent deaths.
116
RrSSANEN
hypothesis, it can be expected that in the population of physically active men coronary atherosclerosis reaches the threshold level of severity necessary for the development of clinical IHD relatively less often than in sedentary men.
III. Extent of Coronary Atherosclerosis in Relation to Occupational Physical Activity in a Series of IHD Deaths The extent of coronary atherosclerosis was assessed by applying the point-counting technique in a series of 109 men aged 35-64 years whose cause of death was classified as IHD on the basis of a routine medico-legal autopsy in the Department of Forensic Medicine, University of Helsinki. In 79 cases, death occurred within 24 h of the onset of the fatal attack, and in the remaining 30 cases, death was unwitnessed. A recent myocardial infarction was found at autopsy in 51 cases. On the basis of occupation, 47 men (43%) were classified as 'sedentary', 49 men (45%) as 'moderately active' and 13 men (12%) as 'active'. The median age in 'sedentary' men was 53 years, in 'moderately active' men 57 years and in 'active' men 53 years. In the series of IHD deaths, no differences were found in the mean extent of coronary raised lesions or calcifications between the 'sedentary', 'moderately active' and 'active' men (fig. 3).
cm 2
~~:{::(:l~ I 11
Calc.
47
10
9 8 7 6 5 4
Raised lesion
Fig. 3. Mean values for the absolute area of coronary raised lesions and calcifications (cm2) in 'sedentary' (S), 'moderately active' (M) and 'active' (A) men in the series of IHD deaths.
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
3 2
Physical Activity and Coronary Artery Disease
117
Clinicopathologic correlations with occupational physical activity were studied in a series of 112 witnessed sudden deaths occurring within 24 h of the onset of the fatal attack. The series was collected from medico-legally autopsied sudden deaths occuring in Helsinki during a period of 12 months. A special methodology was applied at autopsy to the study of the heart; a double contrast coronary angiography was used in the estimation of coronary stenosis [5], and macroscopic histochemistry and histology in the detection of recent myocardial infarction [8, 11]. Information on previous diseases was obtained by the interviewers from the relatives of the patients and from hospital records in association with the study of the Ischaemic Heart Disease Register of Helsinki [8, 10]. On the basis of occupation, 54 men (49%) were classified as 'sedentary', 43 (38%) as 'moderately active' and 15 (13%) as 'active'. In 'sedentary' men, the median age was 57, with an age range from 39 to 65 years, in 'moderately active' men 59, with a range from 31 to 65 years and in 'active' men 57, with a range from 38 to 65 years. The disease history was available for 14 of 15 'active' men. Twelve of them (86%) had suffered from angina pectoris or had a history of myocardial infarction. The remaining two men had a history of an atherosclerotic disease, one a claudication, the other a cerebro-vascular accident. In 'sedentary' men, the prevalence of a previous angina or myocardial infarction was 55%, and in 'moderately active' men 68%. The difference between the 'sedentary' and 'active' men with regard to the history of clinical IHD was significant (the hypergeometric distribution test; p < 0.05). A history of claudication was known in four 'sedentary' men without histories of previous clinicalIHD. No significant differences were found between 'sedentary', 'moderately active' and 'active' men in the occurrence of premonitory symptoms, in the prevalence of a recent or old myocardial infarction obtained at autopsy or in the prevalence of a coronary occlusion or thrombosis (table I). The severity of the occlusive coronary artery disease was estimated using a simple score method. The right coronary artery, left anterior descending coronary artery and left circumflex coronary artery were classified as follows: score 0 = no stenosis or less than half stenosis; score 1 = half stenosis but no occlusion; score 2 = occlusion. The scores for the three main coronary trunks were added up to give a stenosis score for the coronary
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
IV. Disease History and Cardiac Pathology in Relation to Occupational Physical Activity in a Series of Sudden Deaths
RISSANEN
118
Table [. Prevalence of previous symptomatic heart disease, hypertension; premonitory symptoms and autopsy findings of the heart in sedentary, moderately active and active men in the series of sudden deaths
Angina pectoris Myocardial infarction Hypertension Premonitory symptoms Recent myocardial infarction Old myocardial infarction Coronary occlusion Coronary thrombosis
Sedentary men (54 cases)
Moderately active men (43 cases)
Active men (15 cases)
data number % available
data number % available
data number available
~~
49 52 50 49
25 16 15 29
51 31 30 59
40 39 38 40
27 13 13 25
67 33 34 63
13 13 14 11
11 5 1 7
85 38 7 64
54
40
74
43
30
70
15
13
87
54 54 54
35 43 25
65 80 46
43 43 43
32 34 20
74 79 47
15 15 15
10 11 8
67 73 53
arterial tree. The range of this score was thus from 0 to 6. Low stenosis scores from 0 to 3 were more common in 'sedentary' (46%) and 'moderately active' men (40%) than in 'active' men (27%) (fig. 4). The difference between 'sedentary' and 'active' men was not statistically significant in this respect. A single or double vessel disease in coronaries was found in 50% of 'sedentary' men, but in only 20% of 'active' men (the hypergeometric distribution test; p < 0.05). A marked hypertrophy of the heart was much more common in 'sedentary' and 'moderately active' men than in 'active' men (fig. 5). Obviously, this difference was in part but not totally explained by differences in the prevalence of hypertension between groups (table I, fig. 5). The difference between 'sedentary' and 'active' men with regard to the heart weight was significant even though 'hypertensives' were excluded (the Wilcoxon test; p < 0.02).
Conclusions
Many methodological problems are encountered in a study of the present type. The selective composition of postmortem series and the retro-
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 7:57:38 PM
v.
Physical Activity and Coronary Artery Disease
119
No of cases
5[ Active
tOr
L-~0--~--~;~--~--~4--~5~~A~15
Moderately active
10
o
6
4
::f
2°f S,edeo,."
. .
o
5
6
score
Fig. 4. Distribution of 'sedentary', 'moderately active' and 'active' men into groups according to the severity of the occlusive coronary artery disease (score) in the series of sudden deaths (see text for definitions).
HW 9 900
Moderately active
Sedentary
800
Active
~
700 600
a
~
-------"------.t
