Ambulant management of patients with recent myocardial infarction
From the faculty of medicine, University of Manitoba and the Manitoba Clinic, Winnipeg Reprint requests to: Dr. L. Michaels, Manitoba Clinic, 790 Sherbroolc St., Winnipeg, Man. R3A 1M3
to make these estimates for persons who were treated at home. Management depended on estimation of the time lapse between occurrence of the myocardial infarction and its subsequent diagnosis. Generally a patient was admitted to hospital if this interval was thought to be less than 2 to 3 weeks, but, for the most part, bed rest was enforced only if the interval was less than 1 week. If the infarction was thought to have occurred more than 2 to 3 weeks before diagnosis the patient was managed outside the hospital, with restriction of activity advised individually. No restrictions were imposed on patients in whom the diagnosis was not made until more than 1 month afiter the attack. Long-term treatment was medical in all cases and in general conformed to conventional practice. Each patient's course was documented, with special attention to complications. A detailed clinical, electrocardiographic and radiologic assessment was tnade after 6 months. The presence of any symptoms was noted then, together with details of exercise capacity as described by the patient. A physical examination was conducted and, in particular, evidence of cardiac enlargement, signs of heart failure and murmurs were sought. If there was a suggestive elevation of the RS-T segment on the EGG or cardiac enlargement on the chest roentgenogram, cinefluoroscopy was performed in an attempt to detect any ventricular aneurysm. Results The series studied comprised 32 patients - 24 men and 8 women - aged 38 to 84 years (Table I). Sixteen patients had no history of cardiac disease. Five had previously suffered a myocardial infarction and one had had two attacks. There had been previous episodes of acute coronary insufficiency in four patients, uncomplicated angina of effort in four and atypical chest pain in the remaining two. Blood pressure had been recorded before the attack in 20 patients, 14 of whom had
1018 CMA JOURNAL/NOVEMBER 5,
been found to have a systolic pressure greater than 170 mm Hg or a diastolic pressure greater than 90 mm Hg or both. In the other six all blood pressures previously recorded were less than 170/90 mm Hg. In two patients the presenting symptom was sudden onset of severe dyspnea. but in all others it was chest pain. In 23 patients the pain had occurred at rest, the duration varying from half an hour to 2 days. In 18 of the 23 there had been one attack, in 4 two attacks and in 1 three attacks. Seven pa. tients presented with angina of effort; exertional pain had developed de novo in three, pre-existing stable angina had worsened in two and angina of effort had recurred after a lengthy pain-free interval in two. The delay between the onset of symptoms and the diagnosis of myocardial infarction was less than 1 week in 9 patients, 1 week to 1 month in 10 and more than 1 month in the remaining 13. In 15 instances the delay resulted from the patient failing to recognize the significance of the symptoms. Five patients failed to attach importance to changes in either the severity or the frequency of anginal attacks, although they knew of the relation between chest pain and coronary artery disease and recognized the pain as anginal. In eight instances the referring physician did not recognize the nature or appreciate the urgency of the symptoms. In four patients the delay resulted from special circumstances, such as the patient being on vacation. Sixteen patients continued their usual daily activities during the interval between the onset of symptoms and the diagnosis of the infarction. Ten continued at their work, which varied from sedentary occupations to heavy labour. Three engaged in travel, one in work and travel and one in work and formal exercise. Only one patient restricted his activities, by staying at home. Hypertension - systolic, diastolic or both - was discovered by us in 14 instances. The blood pressure was substantially lower than before the attack in two instances. Otherwise, abnormal physical findings were observed in only seven patients at the time of diagnosis - a single abnormality in six and two abnormalities in the seventh. The heart sounds were very soft in four patients, signs of heart failure were observed in three and an apical systolic murmur that proved to be transient was audible in a single case. The EGGs showed that the myocardial infarction was inferior in 20 patients, anterior in 11 and combined in 1. In only two patients did the electrocardiographic diagnosis of a recent infarction depend on comparison with a tracing recorded prior to the attack. In 30 instances either the initial 1977/VOL. 117
or serial tracings indicated that the infarction was recent. The erythrocyte sedimentation rate was high in nine patients, and one or more serum enzyme (SGOT, LDH or CPK) values were high in eight. After the diagnosis was made five patients were admitted to hospital. The remaining 27 were managed at home. most being allowed to continue normal activities. Eighteen patients had been smokers and, notwithstanding advice to the contrary, 17 continued to smoke after the attack. Complications developed in six patients shortly after the diagnosis was made. In two, evidence of congestive cardiac failure became manifest. In single instances there was a temporary decrease in blood pressure, sinus bradycardia, transient complete left bundle branch block and development of the postmyocardial infarction syndrome. Atrial fibrillation had been present previously in one patient and continued without change. Twenty-six patients remained free of complications. There was one death during the 6month follow-up period, in a 60-yearold man in whom 15 weeks had elapsed between the onset of symptoms and the diagnosis of myocardial infarction. He collapsed at home 6 days after first seeing one of us and was pronounced dead on arrival at hospital. At autopsy the diagnosis of an old myocardial infarction was confirmed. Fresh thrombus was found in the anterior descending branch of the left coronary artery. The heart was large but there was no evidence of either a ventricular aneurysm or partial cardiac rupture. The papillary muscles and the interventricular septum were intact. None of the 31 survivors suffered a recurrent myocardial infarction or an attack of acute coronary insufficiency during the 6-month period of observation. At their 6-month assessment 10 patients were having symptoms. Angina of effort was occurring in seven, six of whom had complained of this before the attack; atypical chest pain was present in two and effort dyspnea in one. A systolic blood pressure greater than 170 mm Hg or a diastolic pressure greater than 90 mm Hg, or both, was noted in 14 patients. In the other 17 patients both the systolic and the diastolic pressures were below these levels, either spontaneously or following hypotensive therapy. The apex beat was displaced to the left in one patient, but physical examination did not elicit any other abnormalities in any patient. Persistent elevation of the RS-T segment was present in one patient and cardiac enlargement was evident on roentgenograms in two others. A definite ventricular aneurysm was demonstrated by cinefluoroscopy in only one patient,
although an aneurysm was possibly present in a second and some localized hypokinesia was detected in a third. Discussion Epidemiologists have long recognized that acute myocardial infarction may go undiagnosed at the time of occurrence. The Framingham study,4 for example, revealed that about a quarter of infarctions were discovered only by routine electrocardiography at 6-month examinations. In almost half of these patients, symptoms had been present but had not resulted in diagnosis at the time. It is probable that most, if not all, such patients continued their usual daily activities without self-imposed restrictions and without evident long-term ill effects. Our study was concerned with observations based on the course of comparable patients who remained active after suffering an acute myocardial infarction but who came under close clinical observation during the succeeding days or weeks. We then considered the general applicability of our findings to the permissibility of physical activity in patients with acute myocardial infarction. To justify complete immobilization of patients who suffer an acute myocardial infarction it is necessary to show either that complete bed rest confers demonstrable benefits or that continued activity results in demonstrable harm. Absence of demonstrable harm justifies a liberal approach to continued physical activity in any patient. The manifold disadvantages of even short-term bed rest are well recognized with respect to psychologic,5 general physical,5 metabolic5 and cardiovascular effects,5' and they are to be avoided if at all possible. There has been recent emphasis on the need to avoir or correct any imbalance between requirement for and supply of myocardial oxygen in patients with acute infarction.7 There is therefore a theoretical reason for immobilizing patients in whom either persistent elevation of the RS-T segment or continued pain suggests that the supply of myocardial oxygen is inadequate or that the viability of some part of the myocardium is in jeopardy. However, these considerations would not be applicable to patients who are free of pain and in whom the RS-T segments are isoelectric. Any tendency for exercise to increase the requirement for myocardial oxygen by increasing the blood pressure is detectable with appropriate monitoring and is correctable. Hence there are many patients suffering an acute myocardial infarction for whom there is no theoretical need for complete restriction of activity. Among the patients we studied there were few episodes that could be attn-
buted to failure to rest and these were almost all transient. The single death occurred 16 weeks after the initial episode and the autopsy showed that death was not related to it but rather to a new coronary thrombosis. Our investigation did not include ventriculography and may have underestimated the incidence of ventricular aneurysm. Nevertheless, as judged by clinical observation and cinefluoroscopy, gross manifestations of this complication were exceptional. Assessing the significance of this incidence is difficult in any study, as the reported proportions of patients with myocardial infarction in whom ventricular aneurysm develops vary widely.8'9 In any case, its suggested relation to excessive initial activity8 has not been confirmed.9'10 Among our patients the proportion with cardiac enlargement at follow-up was not unduly great and none had clinical evidence of rupture of the papillary muscles or the interventricular septum. The Framingham follow-up observations were confined to patients who survived an acute myocardial infarction unrecognized at its onset.4 Our study was similarly confined to survivors, its very nature excluding patients who died after the onset of an attack but before obtaining medical attention. However, in no way do we differ with the current emphasis on immediate diagnosis, admission to a coronary care unit and monitoring of all patients who suffer an acute myocardial infarction. Ideally this course should have been followed in our 32 patients. We were concerned in this study solely with the merits and demerits of continued activity after the attack and not with the whereabouts of the patient. In our 32 patients the occurrence of an acute myocardial infarction appears to have been established with reasonable certainty, even if retrospectively. The attacks, however, although definite, were probably milder than would be expected in a completely random group of 32 patients suffering an acute myocardial infarction. The pain tended to be self-limiting and complications were few, transient and mild. The subsequent benign course probably reflects the mildness of the attacks and we are not suggesting that the overall favourable outcome is directly attributable to the continued physical activity of the patients. We are concluding that failure to restrict activity was not obviously harmful in any permanent way. Consequently, enforced rest need not invariably be considered essential even for immediate management of acute myocardial infarction. We recognize that these conclusions apply only to patients comparable to those in our series - that is, persons who suffer a mild and relatively uncomplicated in-
farction and in whom the pain recurs infrequently if at all. It is, of course, possible for an apparently mild and uncomplicated myocardial infarction rapidly to become more severe and complicated. Such changes can, however, be detected immediately with appropriate monitoring, and activity can be restricted as necessary. Any other required therapy can be instituted as quickly as in a patient previously confined to bed. From our findings we conclude that, for selected patients who suffer an acute myocardial infarction, admission to a coronary care unit, close clinical observation and monitoring need not be equated with complete bed rest or total immobilization in other ways. A more liberal approach can be allowed if the infarction is uncomplicated, the patient free of pain, and electrocardiographic evidence of ongoing myocardial ischemia absent. Our experience suggests that under these circumstances the patient can be allowed moderate physical activity, including walking and attendance to activities of daily life. In the continued absence of complications, mobilization can proceed more rapidly; thus the harmful effects of confinement to bed can be avoided and faster and easier rehabilitation allowed. References 1. LEVINE SA: Some harmful effects of recumbency in treatment of heart disease. JAMA 126: 80, 1944 2. ABRAHAM AS, SEVER Y, WEINSTEIN M, et al:
Value of early ambulation in patients with and without complications after acute myocardial infarction. N Engi J Med 292: 719, 1975
3. HARPUR J, CONNER WT, HAMILTON M, et al:
Controlled trial of early mobilization and discharge from hospital in uncomplicated myocardial infarction. Lancel 2: 1331, 1971
4. MARGOLIS JR, KANNEL WS, MANNING F, et
al: Clinical features of unrecognized myocardial infarction - silent and symptomatic. Eighteen year follow-up: the Framingham study. Am J Cardiol 32: 1, 1973
5. DIETRICK JE, WHEDON GD, SHORR E: Effects
of immobilization upon various metabolic and physiologic functions of normal men. Am J Med 4: 3, 1948
6. FAREEDUDDIN K, ABELMANN WH: Impaired orthostatic tolerance after bed rest in patients
with myocardial infarction. N Engi J Med 280: 345, 1969
7. BRAUNWALD E: The reduction of infarct size - an idea whose time (for testing) has come. Circulation 50: 206, 1974 8. SCHL!CHTER J, HELLERSTEIN HK, KATZ LN:
Aneurysm of the heart. A correlative study of one hundred and two proved cases. Medicine (Baltimore) 33: 43, 1954
9. TELLING M, WOOLER GH: Excision of cardiac
aneurysm. Lancel 2: 181, 1961
10. DURNOW MH, BURCHELL LIB, TITUS JL: Post-infarction ventricular aneurysm. A clinicomorphologic and electrocardiographic study
of 80 cases. Am Heart J 70: 753, 1965
CMA JOURNAL/NOVEMBER 5, 1977/VOL. 117
1019
From the faculty of medicine, University of Manitoba and the Manitoba Clinic, Winnipeg Reprint requests to: Dr. L. Michaels, Manitoba Clinic, 790 Sherbroolc St., Winnipeg, Man. R3A 1M3
to make these estimates for persons who were treated at home. Management depended on estimation of the time lapse between occurrence of the myocardial infarction and its subsequent diagnosis. Generally a patient was admitted to hospital if this interval was thought to be less than 2 to 3 weeks, but, for the most part, bed rest was enforced only if the interval was less than 1 week. If the infarction was thought to have occurred more than 2 to 3 weeks before diagnosis the patient was managed outside the hospital, with restriction of activity advised individually. No restrictions were imposed on patients in whom the diagnosis was not made until more than 1 month afiter the attack. Long-term treatment was medical in all cases and in general conformed to conventional practice. Each patient's course was documented, with special attention to complications. A detailed clinical, electrocardiographic and radiologic assessment was tnade after 6 months. The presence of any symptoms was noted then, together with details of exercise capacity as described by the patient. A physical examination was conducted and, in particular, evidence of cardiac enlargement, signs of heart failure and murmurs were sought. If there was a suggestive elevation of the RS-T segment on the EGG or cardiac enlargement on the chest roentgenogram, cinefluoroscopy was performed in an attempt to detect any ventricular aneurysm. Results The series studied comprised 32 patients - 24 men and 8 women - aged 38 to 84 years (Table I). Sixteen patients had no history of cardiac disease. Five had previously suffered a myocardial infarction and one had had two attacks. There had been previous episodes of acute coronary insufficiency in four patients, uncomplicated angina of effort in four and atypical chest pain in the remaining two. Blood pressure had been recorded before the attack in 20 patients, 14 of whom had
1018 CMA JOURNAL/NOVEMBER 5,
been found to have a systolic pressure greater than 170 mm Hg or a diastolic pressure greater than 90 mm Hg or both. In the other six all blood pressures previously recorded were less than 170/90 mm Hg. In two patients the presenting symptom was sudden onset of severe dyspnea. but in all others it was chest pain. In 23 patients the pain had occurred at rest, the duration varying from half an hour to 2 days. In 18 of the 23 there had been one attack, in 4 two attacks and in 1 three attacks. Seven pa. tients presented with angina of effort; exertional pain had developed de novo in three, pre-existing stable angina had worsened in two and angina of effort had recurred after a lengthy pain-free interval in two. The delay between the onset of symptoms and the diagnosis of myocardial infarction was less than 1 week in 9 patients, 1 week to 1 month in 10 and more than 1 month in the remaining 13. In 15 instances the delay resulted from the patient failing to recognize the significance of the symptoms. Five patients failed to attach importance to changes in either the severity or the frequency of anginal attacks, although they knew of the relation between chest pain and coronary artery disease and recognized the pain as anginal. In eight instances the referring physician did not recognize the nature or appreciate the urgency of the symptoms. In four patients the delay resulted from special circumstances, such as the patient being on vacation. Sixteen patients continued their usual daily activities during the interval between the onset of symptoms and the diagnosis of the infarction. Ten continued at their work, which varied from sedentary occupations to heavy labour. Three engaged in travel, one in work and travel and one in work and formal exercise. Only one patient restricted his activities, by staying at home. Hypertension - systolic, diastolic or both - was discovered by us in 14 instances. The blood pressure was substantially lower than before the attack in two instances. Otherwise, abnormal physical findings were observed in only seven patients at the time of diagnosis - a single abnormality in six and two abnormalities in the seventh. The heart sounds were very soft in four patients, signs of heart failure were observed in three and an apical systolic murmur that proved to be transient was audible in a single case. The EGGs showed that the myocardial infarction was inferior in 20 patients, anterior in 11 and combined in 1. In only two patients did the electrocardiographic diagnosis of a recent infarction depend on comparison with a tracing recorded prior to the attack. In 30 instances either the initial 1977/VOL. 117
or serial tracings indicated that the infarction was recent. The erythrocyte sedimentation rate was high in nine patients, and one or more serum enzyme (SGOT, LDH or CPK) values were high in eight. After the diagnosis was made five patients were admitted to hospital. The remaining 27 were managed at home. most being allowed to continue normal activities. Eighteen patients had been smokers and, notwithstanding advice to the contrary, 17 continued to smoke after the attack. Complications developed in six patients shortly after the diagnosis was made. In two, evidence of congestive cardiac failure became manifest. In single instances there was a temporary decrease in blood pressure, sinus bradycardia, transient complete left bundle branch block and development of the postmyocardial infarction syndrome. Atrial fibrillation had been present previously in one patient and continued without change. Twenty-six patients remained free of complications. There was one death during the 6month follow-up period, in a 60-yearold man in whom 15 weeks had elapsed between the onset of symptoms and the diagnosis of myocardial infarction. He collapsed at home 6 days after first seeing one of us and was pronounced dead on arrival at hospital. At autopsy the diagnosis of an old myocardial infarction was confirmed. Fresh thrombus was found in the anterior descending branch of the left coronary artery. The heart was large but there was no evidence of either a ventricular aneurysm or partial cardiac rupture. The papillary muscles and the interventricular septum were intact. None of the 31 survivors suffered a recurrent myocardial infarction or an attack of acute coronary insufficiency during the 6-month period of observation. At their 6-month assessment 10 patients were having symptoms. Angina of effort was occurring in seven, six of whom had complained of this before the attack; atypical chest pain was present in two and effort dyspnea in one. A systolic blood pressure greater than 170 mm Hg or a diastolic pressure greater than 90 mm Hg, or both, was noted in 14 patients. In the other 17 patients both the systolic and the diastolic pressures were below these levels, either spontaneously or following hypotensive therapy. The apex beat was displaced to the left in one patient, but physical examination did not elicit any other abnormalities in any patient. Persistent elevation of the RS-T segment was present in one patient and cardiac enlargement was evident on roentgenograms in two others. A definite ventricular aneurysm was demonstrated by cinefluoroscopy in only one patient,
although an aneurysm was possibly present in a second and some localized hypokinesia was detected in a third. Discussion Epidemiologists have long recognized that acute myocardial infarction may go undiagnosed at the time of occurrence. The Framingham study,4 for example, revealed that about a quarter of infarctions were discovered only by routine electrocardiography at 6-month examinations. In almost half of these patients, symptoms had been present but had not resulted in diagnosis at the time. It is probable that most, if not all, such patients continued their usual daily activities without self-imposed restrictions and without evident long-term ill effects. Our study was concerned with observations based on the course of comparable patients who remained active after suffering an acute myocardial infarction but who came under close clinical observation during the succeeding days or weeks. We then considered the general applicability of our findings to the permissibility of physical activity in patients with acute myocardial infarction. To justify complete immobilization of patients who suffer an acute myocardial infarction it is necessary to show either that complete bed rest confers demonstrable benefits or that continued activity results in demonstrable harm. Absence of demonstrable harm justifies a liberal approach to continued physical activity in any patient. The manifold disadvantages of even short-term bed rest are well recognized with respect to psychologic,5 general physical,5 metabolic5 and cardiovascular effects,5' and they are to be avoided if at all possible. There has been recent emphasis on the need to avoir or correct any imbalance between requirement for and supply of myocardial oxygen in patients with acute infarction.7 There is therefore a theoretical reason for immobilizing patients in whom either persistent elevation of the RS-T segment or continued pain suggests that the supply of myocardial oxygen is inadequate or that the viability of some part of the myocardium is in jeopardy. However, these considerations would not be applicable to patients who are free of pain and in whom the RS-T segments are isoelectric. Any tendency for exercise to increase the requirement for myocardial oxygen by increasing the blood pressure is detectable with appropriate monitoring and is correctable. Hence there are many patients suffering an acute myocardial infarction for whom there is no theoretical need for complete restriction of activity. Among the patients we studied there were few episodes that could be attn-
buted to failure to rest and these were almost all transient. The single death occurred 16 weeks after the initial episode and the autopsy showed that death was not related to it but rather to a new coronary thrombosis. Our investigation did not include ventriculography and may have underestimated the incidence of ventricular aneurysm. Nevertheless, as judged by clinical observation and cinefluoroscopy, gross manifestations of this complication were exceptional. Assessing the significance of this incidence is difficult in any study, as the reported proportions of patients with myocardial infarction in whom ventricular aneurysm develops vary widely.8'9 In any case, its suggested relation to excessive initial activity8 has not been confirmed.9'10 Among our patients the proportion with cardiac enlargement at follow-up was not unduly great and none had clinical evidence of rupture of the papillary muscles or the interventricular septum. The Framingham follow-up observations were confined to patients who survived an acute myocardial infarction unrecognized at its onset.4 Our study was similarly confined to survivors, its very nature excluding patients who died after the onset of an attack but before obtaining medical attention. However, in no way do we differ with the current emphasis on immediate diagnosis, admission to a coronary care unit and monitoring of all patients who suffer an acute myocardial infarction. Ideally this course should have been followed in our 32 patients. We were concerned in this study solely with the merits and demerits of continued activity after the attack and not with the whereabouts of the patient. In our 32 patients the occurrence of an acute myocardial infarction appears to have been established with reasonable certainty, even if retrospectively. The attacks, however, although definite, were probably milder than would be expected in a completely random group of 32 patients suffering an acute myocardial infarction. The pain tended to be self-limiting and complications were few, transient and mild. The subsequent benign course probably reflects the mildness of the attacks and we are not suggesting that the overall favourable outcome is directly attributable to the continued physical activity of the patients. We are concluding that failure to restrict activity was not obviously harmful in any permanent way. Consequently, enforced rest need not invariably be considered essential even for immediate management of acute myocardial infarction. We recognize that these conclusions apply only to patients comparable to those in our series - that is, persons who suffer a mild and relatively uncomplicated in-
farction and in whom the pain recurs infrequently if at all. It is, of course, possible for an apparently mild and uncomplicated myocardial infarction rapidly to become more severe and complicated. Such changes can, however, be detected immediately with appropriate monitoring, and activity can be restricted as necessary. Any other required therapy can be instituted as quickly as in a patient previously confined to bed. From our findings we conclude that, for selected patients who suffer an acute myocardial infarction, admission to a coronary care unit, close clinical observation and monitoring need not be equated with complete bed rest or total immobilization in other ways. A more liberal approach can be allowed if the infarction is uncomplicated, the patient free of pain, and electrocardiographic evidence of ongoing myocardial ischemia absent. Our experience suggests that under these circumstances the patient can be allowed moderate physical activity, including walking and attendance to activities of daily life. In the continued absence of complications, mobilization can proceed more rapidly; thus the harmful effects of confinement to bed can be avoided and faster and easier rehabilitation allowed. References 1. LEVINE SA: Some harmful effects of recumbency in treatment of heart disease. JAMA 126: 80, 1944 2. ABRAHAM AS, SEVER Y, WEINSTEIN M, et al:
Value of early ambulation in patients with and without complications after acute myocardial infarction. N Engi J Med 292: 719, 1975
3. HARPUR J, CONNER WT, HAMILTON M, et al:
Controlled trial of early mobilization and discharge from hospital in uncomplicated myocardial infarction. Lancel 2: 1331, 1971
4. MARGOLIS JR, KANNEL WS, MANNING F, et
al: Clinical features of unrecognized myocardial infarction - silent and symptomatic. Eighteen year follow-up: the Framingham study. Am J Cardiol 32: 1, 1973
5. DIETRICK JE, WHEDON GD, SHORR E: Effects
of immobilization upon various metabolic and physiologic functions of normal men. Am J Med 4: 3, 1948
6. FAREEDUDDIN K, ABELMANN WH: Impaired orthostatic tolerance after bed rest in patients
with myocardial infarction. N Engi J Med 280: 345, 1969
7. BRAUNWALD E: The reduction of infarct size - an idea whose time (for testing) has come. Circulation 50: 206, 1974 8. SCHL!CHTER J, HELLERSTEIN HK, KATZ LN:
Aneurysm of the heart. A correlative study of one hundred and two proved cases. Medicine (Baltimore) 33: 43, 1954
9. TELLING M, WOOLER GH: Excision of cardiac
aneurysm. Lancel 2: 181, 1961
10. DURNOW MH, BURCHELL LIB, TITUS JL: Post-infarction ventricular aneurysm. A clinicomorphologic and electrocardiographic study
of 80 cases. Am Heart J 70: 753, 1965
CMA JOURNAL/NOVEMBER 5, 1977/VOL. 117
1019
