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Physical fitness cannot be used to predict the likelihood of acute coronary syndromes in ED patients with chest pain
American Journal of Emergency Medicine (2012) 30, 57–60
www.elsevier.com/locate/ajem
Original Contribution
Physical fitness cannot be used to predict the likelihood of acute coronary syndromes in ED patients with chest pain Taku Taira MD, Breena R. Taira MD, MPH ⁎, Jasmine Chohan, Daniel Dickinson MD, Regina M. Troxell, Henry C. Thode Jr. PhD, Adam J. Singer MD Department of Emergency Medicine, Stony Brook University Medical Center, Stony Brook, New York 11794-8191, USA Received 18 July 2010; accepted 30 July 2010
Abstract Objective: The objective of the study was to explore the association between physical fitness and the likelihood of acute coronary syndrome (ACS) in patients presenting to the emergency department (ED) with chest pain (CP). We hypothesized that the likelihood of ACS would be lower in physically fit patients and higher in patients with exercise-induced CP. Methods: The study involved a prospective, descriptive cohort in an academic suburban ED. Subjects were ED patients with CP admitted for suspected ACS. Demographic and clinical data were collected by trained research assistants using standardized forms. Patients were surveyed on level of fitness and whether they had ever experienced anginal type symptoms during exercise. Acute coronary syndrome was considered present if the patient had electrocardiographic evidence of infarction or ischemia; elevated troponin I levels; greater than 70% stenosis of culprit coronary artery; or a positive nuclear, echocardiographic, or treadmill stress test result. Patients readmitted within 30 days for reinfarction, cardiogenic shock, or arrhythmias were also considered to have ACS. The association between physical fitness and ACS was determined using χ2 tests and odds ratios (ORs). Results: One hundred patients were enrolled. Mean age was 55.8 (±15.3) years; 36% were female; 85% were white. Thirteen (13%) patients had positive troponins, 22 of 36 catheterized patients had greater than 70% coronary artery stenosis, and 6 (6%) had abnormal stress test results. There were no deaths or reinfarctions within 30 days. The rate of ACS was similar in patients who were physically fit and those who were not (24% vs 37%; OR, 0.5 [95% confidence interval, 0.2-1.3]) and in patients who had experienced exercise-induced CP and those who had not (32% vs 29%; OR, 1.2 [95% confidence interval, 0.4-3.2]). Neither the frequency nor the intensity of exercise was associated with ACS. Conclusions: Physically fit patients with CP were as likely to have ACS as those not physically fit. A history of exercise-induced CP was not associated with an increased likelihood of ACS. © 2012 Elsevier Inc. All rights reserved.
1. Introduction
⁎ Corresponding author. Tel.: +1 631 444 8351; fax: +1 631 444 9719. E-mail address: [email protected] (B.R. Taira). 0735-6757/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2010.07.027
The health benefits of exercise have been well documented [1-4]. Regular physical activity has been known to prevent the development of coronary artery disease (CAD) and reduce the risk of cardiovascular death [2,5-9]. However,
58 despite the multiple recommendations from a variety of public health organizations, we live in a primarily sedentary society, with 39% of US adults reporting no leisure time physical activity [4]. Although clinicians are aware of the health benefits of exercise, the association between a patient's physical fitness and the likelihood of acute coronary syndrome (ACS) in patients presenting to the emergency department (ED) with chest pain has not been well established. Although there is a lack of evidence, emergency physicians or cardiologists may be tempted to use a history of physical fitness and a lack of exercise-induced chest pain to rule out ACS in patients with chest pain. It is important to establish the safety of such an approach because, despite our best efforts, emergency physicians miss 2% to 5% of patients with myocardial infarction (MI) [10-12]. At the same time, there are multiple incentives to identify low-risk patients, who can be safely discharged, including patient inconvenience, hospital overcrowding, and cost containment. The current study was designed to address this question by determining the association between physical fitness and ACS in patients presenting to the ED with chest pain. We hypothesized that the likelihood of ACS would be lower in physically fit patients and higher in patients with exerciseinduced CP.
T. Taira et al. reported level of fitness and whether they had ever experienced anginal symptoms during exercise. This information was elicited via the following questions: Do you exercise regularly? Have you experienced CP/SOB during or after exercise? Aside from any work you do at home or at a job, do you do anything regularly—that is, on a daily basis— that helps you keep physically fit? How often do you participate in moderate physical activity (bowling, golf, light sports, gardening, long walks) (rarely/never, 1/wk to a few times a week, 2-4/wk, N4/wk) [14]. How often do you participate in vigorous physical activity? (jogging, racket sports, swimming, aerobics) (rarely/never, 1/wk to a few times a week, 2-4/wk, N4/wk).
2.5. Outcomes The primary outcome was the presence of ACS. Acute coronary syndrome was considered present if the patient had electrocardiographic evidence of infarction or ischemia; elevated troponin I levels; greater than 70% stenosis of culprit coronary artery; or a positive nuclear, echocardiographic, or treadmill stress test result. Patients readmitted within 30 days for reinfarction, cardiogenic shock, or arrhythmias were also considered to have ACS.
2.6. Data analysis
2. Methods 2.1. Study design A prospective observational study design was used to test the study hypothesis. The study was approved by our Institutional Review Board, and all patients gave written informed consent.
2.2. Setting The study took place in a suburban ED of an academic institution with an annual average number of visits of 75, 000 per year. Our institution has a heart center and percutaneous coronary intervention capability.
2.3. Population All ED patients with chest pain who were admitted for suspected ACS were eligible for enrollment. Excluded were non-English speakers and those younger than 18 years.
2.4. Measures Data collected included demographic and clinical information collected by trained research assistants using standardized forms [13]. Patients were surveyed on self-
SPSS (SPSS Inc, Chicago, IL) for Windows version 17.0 was used for analysis. The association between physical fitness and ACS was determined using χ2 tests and odds ratios (ORs). Multivariate analysis for predicting ACS was performed using logistic regression. A P value of .05 was the level used to determine statistical significance.
Table 1 Characteristics of patients admitted for ACS by physical fitness
Mean age (SD) % Female % Exercise-induced CP Positive troponins % Catheterization % Severe stenosis % Positive stress test result % Total ACS % 30-d reinfarction % 30-d mortality
Physically fit (n = 42a)
Not physically fit (n = 51a)
57 (15) 40.5 40.5
54 (15) 33.3 19.5
.30 .48 .04
15.8 34.2 50.0 14.3
14.6 43.8 61.9 23.5
.88 .37 .49 .52
23.8 0 0
37.3 0 0
P value
.16 – –
CP indicates chest pain. a Because of some missing data, this is the maximum sample size for each comparison.
Physical fitness is not a predictor of acute coronary syndromes
59
3. Results
4. Discussion
A total of 100 patients were enrolled in the study. The mean age was 55.8 (±15.3) years. Thirty-six percent were female, and 85% were white. Their demographic and clinical characteristics are presented in Table 1. Thirty-six percent said that they exercised regularly, and 45% stated that they were physically fit. Twenty-five percent of those enrolled stated they had a history of exercise-induced chest pain. Of the 100 patients with suspected ACS, 13 (13%) patients had positive troponins. Thirty-six patients underwent catheterization; and of those, 22 (61%) had greater than 70% stenosis of a coronary artery. Of the 33 patients who had stress tests performed, 6 (20%) had abnormal stress test results. Overall, 31 patients had a final diagnosis of ACS. There were no deaths or reinfarctions within 30 days. Seven enrollees did not indicate whether they were physically fit or not, and were excluded from any analysis comparing the fit and nonfit group. The mean age for those who considered themselves fit did not differ from the mean age of those who did not (54 vs 57, P = .30). The rate of ACS was similar in patients who reported that they were physically fit compared with those who were not (24% vs 37%; OR, 0.5 [95% confidence interval, 0.2-1.3]). Rates of ACS were also similar between patients who had experienced exercise-induced chest pain compared with those who had not (32% vs 29%; OR, 1.2 [95% confidence interval, 0.4-3.2]) (Table 2). Furthermore, the frequency and intensity of exercise were not associated with ACS. Because of the limited sample size, a maximum of 3 factors could only be considered for a logistic regression. Inasmuch as our hypotheses were based on exercise-induced CP and fitness, we examined a multivariate model that included only those factors as predictors of ACS; as with the univariate results, a model including both factors showed no significant association with a diagnosis of ACS. A stepwise model that included additional risk factors showed that sex and prior MI were predictive of ACS.
In this study, self-reported level of physical fitness did not predict the likelihood of ACS in patients presenting to the ED with chest pain. In addition, a history of exerciseinduced angina did not predict ACS in these patients either. Although surprising, our findings are consistent with previous studies that show that the absence of cardiac risk factors is insufficient to rule out ACS as the cause of chest pain [15-18]. The cardiovascular benefits of exercise are well documented. Exercise has been shown to decrease both morbidity and mortality in patients with CAD [5,19-22] as well as to modify other cardiac risk factors including diabetes and hypertension [5,9]. Exercise has been shown to decrease thrombosis, inflammation, and endothelial dysfunction, all of which contribute to the development and progression of CAD [9,23]. Not only do patients who are physically fit have lower rates of CAD [2,3,5,24], physically fit patients who have CAD have less severe CAD when compared with their sedentary counterparts [3,22,25]. Although physical activity decreases the risk of CAD, it is important to note that it does not eliminate that risk [24]. Even highly trained athletes, such as marathon runners, have been shown to have CAD [26]. The result of this study is illustrated by the case of the world-class marathon runner Alberto Salazar who had cardiac arrest after an MI despite his excellent athletic condition [27]. Our results suggest that ACS should not be excluded in ED patients with chest pain just because they consider themselves physically fit or in the absence of exerciseinduced chest pain.
Table 2
This study has several limitations. Our study population included patients who were admitted for ACS and not all patients who presented with chest pain; therefore, we cannot account for providers' clinical decision-making or selection
Characteristics of patients admitted for ACS by exercise-induced chest pain
Mean age (SD) % Female % Physically fit Positive troponins % Catheterization % Severe stenosis % Positive stress test result % Total ACS % 30-d reinfarction % 30-d mortality a
4.1. Limitations
Exercise-induced chest pain (n = 25 a)
No exercise-induced chest pain (n = 59 a)
53 (14) 48.0 68.0 17.4 39.1 60.0 25.0 32.0 0 0
55 (16) 32.2 43.1 12.7 38.2 57.1 15.0 28.8 0 0
Because of some missing data, this is the maximum sample size for each comparison.
P value .56 .17 .04 .59 .94 .88 .53 .77 – –
60 bias. It is possible that there were patients who were discharged because of their exercise tolerance. In addition, the degree of physical activity was self-reported and may be inaccurate [28]. However, physicians must rely on selfreported fitness in the ED because formal fitness tests cannot be obtained in the ED. Finally, the small study size resulted in wide confidence intervals and cannot reliably rule out a type 2 error. We are now conducting a larger multicenter study that will address these limitations.
5. Conclusions Patient self-reported level of physical fitness and reported lack of a history of exercise-induced anginal symptoms are insufficient to exclude ACS in ED patients who are being admitted for chest pain. This portion of the history should be taken in the clinical context when making a decision about patient disposition.
References [1] Wannamethee SG, Shaper AG. Physical activity in the prevention of cardiovascular disease: an epidemiological perspective. Sports Med 2001;31:101-14. [2] Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004;364:937-52. [3] Al-Khalili F, Janszky I, Andersson A, Svane B, Schenck-Gustafsson K. Physical activity and exercise performance predict long-term prognosis in middle-aged women surviving acute coronary syndrome. J Intern Med 2007;261:178-87. [4] Statistics NCfH. Health, United States, 2008. Hyattsville, MD: National Center for Health Statistics; 2009. [5] Karmisholt K, Gotzsche PC. Physical activity for secondary prevention of disease. Systematic reviews of randomised clinical trials. Dan Med Bull 2005;52:90-4. [6] Fletcher GF, Balady G, Blair SN, et al. Statement on exercise: benefits and recommendations for physical activity programs for all Americans. A statement for health professionals by the Committee on Exercise and Cardiac Rehabilitation of the Council on Clinical Cardiology, American Heart Association. Circulation 1996;94:857-62. [7] Fletcher GF, Balady GJ, Amsterdam EA, et al. Exercise standards for testing and training: a statement for healthcare professionals from the American Heart Association. Circulation 2001;104:1694-740. [8] Pate RR, Pratt M, Blair SN, et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402-7. [9] Scrutinio D, Bellotto F, Lagioia R, Passantino A. Physical activity for coronary heart disease: cardioprotective mechanisms and effects on prognosis. Monaldi Arch Chest Dis 2005;64:77-87. [10] Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000;342:1163-70.
T. Taira et al. [11] Dagnone E, Collier C, Pickett W, et al. Chest pain with nondiagnostic electrocardiogram in the emergency department: a randomized controlled trial of two cardiac marker regimens. CMAJ 2000;162: 1561-6. [12] Miller CD, Lindsell CJ, Khandelwal S, et al. Is the initial diagnostic impression of “noncardiac chest pain” adequate to exclude cardiac disease? Ann Emerg Med 2004;44:565-74. [13] Hollander JE, Blomkalns AL, Brogan GX, et al. Standardized reporting guidelines for studies evaluating risk stratification of ED patients with potential acute coronary syndromes. Acad Emerg Med 2004;11:1331-40. [14] Kushi LH, Fee RM, Folsom AR, Mink PJ, Anderson KE, Sellers TA. Physical activity and mortality in postmenopausal women. JAMA 1997;277:1287-92. [15] Han JH, Lindsell CJ, Storrow AB, et al. The role of cardiac risk factor burden in diagnosing acute coronary syndromes in the emergency department setting. Ann Emerg Med 2007;49:145-52, 52 e1. [16] Antman EM, Cohen M, Bernink PJ, et al. The TIMI risk score for unstable angina/non-ST elevation MI: a method for prognostication and therapeutic decision making. JAMA 2000;284:835-42. [17] Jayes Jr RL, Beshansky JR, D'Agostino RB, Selker HP. Do patients' coronary risk factor reports predict acute cardiac ischemia in the emergency department? A multicenter study. J Clin Epidemiol 1992;45:621-6. [18] Pollack Jr CV, Sites FD, Shofer FS, Sease KL, Hollander JE. Application of the TIMI risk score for unstable angina and non-ST elevation acute coronary syndrome to an unselected emergency department chest pain population. Acad Emerg Med 2006;13:13-8. [19] Blair SN, Kohl 3rd HW, Paffenbarger Jr RS, Clark DG, Cooper KH, Gibbons LW. Physical fitness and all-cause mortality. A prospective study of healthy men and women. JAMA 1989;262:2395-401. [20] Stevens J, Cai J, Evenson KR, Thomas R. Fitness and fatness as predictors of mortality from all causes and from cardiovascular disease in men and women in the lipid research clinics study. Am J Epidemiol 2002;156:832-41. [21] Todd IC, Bradnam MS, Cooke MB, Ballantyne D. Effects of daily high-intensity exercise on myocardial perfusion in angina pectoris. Am J Cardiol 1991;68:1593-9. [22] Ciampricotti R, Deckers JW, Taverne R, el Gamal M, Relik-van Wely L, Pool J. Characteristics of conditioned and sedentary men with acute coronary syndromes. Am J Cardiol 1994;73:219-22. [23] Brun JF, Khaled S, Raynaud E, Bouix D, Micallef JP, Orsetti A. The triphasic effects of exercise on blood rheology: which relevance to physiology and pathophysiology? Clin Hemorheol Microcirc 1998;19: 89-104. [24] Rothenbacher D, Koenig W, Brenner H. Lifetime physical activity patterns and risk of coronary heart disease. Heart 2006;92:1319-20. [25] Makrilakis K, Panagiotakos DB, Pitsavos C, et al. The association between physical activity and the development of acute coronary syndromes in diabetic subjects (the CARDIO2000 II study). Eur J Cardiovasc Prev Rehabil 2004;11:298-303. [26] Noakes T, Opie L, Beck W, McKechnie J, Benchimol A, Desser K. Coronary heart disease in marathon runners. Ann N Y Acad Sci 1977;301:593-619. [27] Brant J. The marathoner speaks to his God. New York, NY: PLAY The New York Times Sports Magazine; 2007. [28] Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med 1992;327:1893-8.
www.elsevier.com/locate/ajem
Original Contribution
Physical fitness cannot be used to predict the likelihood of acute coronary syndromes in ED patients with chest pain Taku Taira MD, Breena R. Taira MD, MPH ⁎, Jasmine Chohan, Daniel Dickinson MD, Regina M. Troxell, Henry C. Thode Jr. PhD, Adam J. Singer MD Department of Emergency Medicine, Stony Brook University Medical Center, Stony Brook, New York 11794-8191, USA Received 18 July 2010; accepted 30 July 2010
Abstract Objective: The objective of the study was to explore the association between physical fitness and the likelihood of acute coronary syndrome (ACS) in patients presenting to the emergency department (ED) with chest pain (CP). We hypothesized that the likelihood of ACS would be lower in physically fit patients and higher in patients with exercise-induced CP. Methods: The study involved a prospective, descriptive cohort in an academic suburban ED. Subjects were ED patients with CP admitted for suspected ACS. Demographic and clinical data were collected by trained research assistants using standardized forms. Patients were surveyed on level of fitness and whether they had ever experienced anginal type symptoms during exercise. Acute coronary syndrome was considered present if the patient had electrocardiographic evidence of infarction or ischemia; elevated troponin I levels; greater than 70% stenosis of culprit coronary artery; or a positive nuclear, echocardiographic, or treadmill stress test result. Patients readmitted within 30 days for reinfarction, cardiogenic shock, or arrhythmias were also considered to have ACS. The association between physical fitness and ACS was determined using χ2 tests and odds ratios (ORs). Results: One hundred patients were enrolled. Mean age was 55.8 (±15.3) years; 36% were female; 85% were white. Thirteen (13%) patients had positive troponins, 22 of 36 catheterized patients had greater than 70% coronary artery stenosis, and 6 (6%) had abnormal stress test results. There were no deaths or reinfarctions within 30 days. The rate of ACS was similar in patients who were physically fit and those who were not (24% vs 37%; OR, 0.5 [95% confidence interval, 0.2-1.3]) and in patients who had experienced exercise-induced CP and those who had not (32% vs 29%; OR, 1.2 [95% confidence interval, 0.4-3.2]). Neither the frequency nor the intensity of exercise was associated with ACS. Conclusions: Physically fit patients with CP were as likely to have ACS as those not physically fit. A history of exercise-induced CP was not associated with an increased likelihood of ACS. © 2012 Elsevier Inc. All rights reserved.
1. Introduction
⁎ Corresponding author. Tel.: +1 631 444 8351; fax: +1 631 444 9719. E-mail address: [email protected] (B.R. Taira). 0735-6757/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2010.07.027
The health benefits of exercise have been well documented [1-4]. Regular physical activity has been known to prevent the development of coronary artery disease (CAD) and reduce the risk of cardiovascular death [2,5-9]. However,
58 despite the multiple recommendations from a variety of public health organizations, we live in a primarily sedentary society, with 39% of US adults reporting no leisure time physical activity [4]. Although clinicians are aware of the health benefits of exercise, the association between a patient's physical fitness and the likelihood of acute coronary syndrome (ACS) in patients presenting to the emergency department (ED) with chest pain has not been well established. Although there is a lack of evidence, emergency physicians or cardiologists may be tempted to use a history of physical fitness and a lack of exercise-induced chest pain to rule out ACS in patients with chest pain. It is important to establish the safety of such an approach because, despite our best efforts, emergency physicians miss 2% to 5% of patients with myocardial infarction (MI) [10-12]. At the same time, there are multiple incentives to identify low-risk patients, who can be safely discharged, including patient inconvenience, hospital overcrowding, and cost containment. The current study was designed to address this question by determining the association between physical fitness and ACS in patients presenting to the ED with chest pain. We hypothesized that the likelihood of ACS would be lower in physically fit patients and higher in patients with exerciseinduced CP.
T. Taira et al. reported level of fitness and whether they had ever experienced anginal symptoms during exercise. This information was elicited via the following questions: Do you exercise regularly? Have you experienced CP/SOB during or after exercise? Aside from any work you do at home or at a job, do you do anything regularly—that is, on a daily basis— that helps you keep physically fit? How often do you participate in moderate physical activity (bowling, golf, light sports, gardening, long walks) (rarely/never, 1/wk to a few times a week, 2-4/wk, N4/wk) [14]. How often do you participate in vigorous physical activity? (jogging, racket sports, swimming, aerobics) (rarely/never, 1/wk to a few times a week, 2-4/wk, N4/wk).
2.5. Outcomes The primary outcome was the presence of ACS. Acute coronary syndrome was considered present if the patient had electrocardiographic evidence of infarction or ischemia; elevated troponin I levels; greater than 70% stenosis of culprit coronary artery; or a positive nuclear, echocardiographic, or treadmill stress test result. Patients readmitted within 30 days for reinfarction, cardiogenic shock, or arrhythmias were also considered to have ACS.
2.6. Data analysis
2. Methods 2.1. Study design A prospective observational study design was used to test the study hypothesis. The study was approved by our Institutional Review Board, and all patients gave written informed consent.
2.2. Setting The study took place in a suburban ED of an academic institution with an annual average number of visits of 75, 000 per year. Our institution has a heart center and percutaneous coronary intervention capability.
2.3. Population All ED patients with chest pain who were admitted for suspected ACS were eligible for enrollment. Excluded were non-English speakers and those younger than 18 years.
2.4. Measures Data collected included demographic and clinical information collected by trained research assistants using standardized forms [13]. Patients were surveyed on self-
SPSS (SPSS Inc, Chicago, IL) for Windows version 17.0 was used for analysis. The association between physical fitness and ACS was determined using χ2 tests and odds ratios (ORs). Multivariate analysis for predicting ACS was performed using logistic regression. A P value of .05 was the level used to determine statistical significance.
Table 1 Characteristics of patients admitted for ACS by physical fitness
Mean age (SD) % Female % Exercise-induced CP Positive troponins % Catheterization % Severe stenosis % Positive stress test result % Total ACS % 30-d reinfarction % 30-d mortality
Physically fit (n = 42a)
Not physically fit (n = 51a)
57 (15) 40.5 40.5
54 (15) 33.3 19.5
.30 .48 .04
15.8 34.2 50.0 14.3
14.6 43.8 61.9 23.5
.88 .37 .49 .52
23.8 0 0
37.3 0 0
P value
.16 – –
CP indicates chest pain. a Because of some missing data, this is the maximum sample size for each comparison.
Physical fitness is not a predictor of acute coronary syndromes
59
3. Results
4. Discussion
A total of 100 patients were enrolled in the study. The mean age was 55.8 (±15.3) years. Thirty-six percent were female, and 85% were white. Their demographic and clinical characteristics are presented in Table 1. Thirty-six percent said that they exercised regularly, and 45% stated that they were physically fit. Twenty-five percent of those enrolled stated they had a history of exercise-induced chest pain. Of the 100 patients with suspected ACS, 13 (13%) patients had positive troponins. Thirty-six patients underwent catheterization; and of those, 22 (61%) had greater than 70% stenosis of a coronary artery. Of the 33 patients who had stress tests performed, 6 (20%) had abnormal stress test results. Overall, 31 patients had a final diagnosis of ACS. There were no deaths or reinfarctions within 30 days. Seven enrollees did not indicate whether they were physically fit or not, and were excluded from any analysis comparing the fit and nonfit group. The mean age for those who considered themselves fit did not differ from the mean age of those who did not (54 vs 57, P = .30). The rate of ACS was similar in patients who reported that they were physically fit compared with those who were not (24% vs 37%; OR, 0.5 [95% confidence interval, 0.2-1.3]). Rates of ACS were also similar between patients who had experienced exercise-induced chest pain compared with those who had not (32% vs 29%; OR, 1.2 [95% confidence interval, 0.4-3.2]) (Table 2). Furthermore, the frequency and intensity of exercise were not associated with ACS. Because of the limited sample size, a maximum of 3 factors could only be considered for a logistic regression. Inasmuch as our hypotheses were based on exercise-induced CP and fitness, we examined a multivariate model that included only those factors as predictors of ACS; as with the univariate results, a model including both factors showed no significant association with a diagnosis of ACS. A stepwise model that included additional risk factors showed that sex and prior MI were predictive of ACS.
In this study, self-reported level of physical fitness did not predict the likelihood of ACS in patients presenting to the ED with chest pain. In addition, a history of exerciseinduced angina did not predict ACS in these patients either. Although surprising, our findings are consistent with previous studies that show that the absence of cardiac risk factors is insufficient to rule out ACS as the cause of chest pain [15-18]. The cardiovascular benefits of exercise are well documented. Exercise has been shown to decrease both morbidity and mortality in patients with CAD [5,19-22] as well as to modify other cardiac risk factors including diabetes and hypertension [5,9]. Exercise has been shown to decrease thrombosis, inflammation, and endothelial dysfunction, all of which contribute to the development and progression of CAD [9,23]. Not only do patients who are physically fit have lower rates of CAD [2,3,5,24], physically fit patients who have CAD have less severe CAD when compared with their sedentary counterparts [3,22,25]. Although physical activity decreases the risk of CAD, it is important to note that it does not eliminate that risk [24]. Even highly trained athletes, such as marathon runners, have been shown to have CAD [26]. The result of this study is illustrated by the case of the world-class marathon runner Alberto Salazar who had cardiac arrest after an MI despite his excellent athletic condition [27]. Our results suggest that ACS should not be excluded in ED patients with chest pain just because they consider themselves physically fit or in the absence of exerciseinduced chest pain.
Table 2
This study has several limitations. Our study population included patients who were admitted for ACS and not all patients who presented with chest pain; therefore, we cannot account for providers' clinical decision-making or selection
Characteristics of patients admitted for ACS by exercise-induced chest pain
Mean age (SD) % Female % Physically fit Positive troponins % Catheterization % Severe stenosis % Positive stress test result % Total ACS % 30-d reinfarction % 30-d mortality a
4.1. Limitations
Exercise-induced chest pain (n = 25 a)
No exercise-induced chest pain (n = 59 a)
53 (14) 48.0 68.0 17.4 39.1 60.0 25.0 32.0 0 0
55 (16) 32.2 43.1 12.7 38.2 57.1 15.0 28.8 0 0
Because of some missing data, this is the maximum sample size for each comparison.
P value .56 .17 .04 .59 .94 .88 .53 .77 – –
60 bias. It is possible that there were patients who were discharged because of their exercise tolerance. In addition, the degree of physical activity was self-reported and may be inaccurate [28]. However, physicians must rely on selfreported fitness in the ED because formal fitness tests cannot be obtained in the ED. Finally, the small study size resulted in wide confidence intervals and cannot reliably rule out a type 2 error. We are now conducting a larger multicenter study that will address these limitations.
5. Conclusions Patient self-reported level of physical fitness and reported lack of a history of exercise-induced anginal symptoms are insufficient to exclude ACS in ED patients who are being admitted for chest pain. This portion of the history should be taken in the clinical context when making a decision about patient disposition.
References [1] Wannamethee SG, Shaper AG. Physical activity in the prevention of cardiovascular disease: an epidemiological perspective. Sports Med 2001;31:101-14. [2] Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004;364:937-52. [3] Al-Khalili F, Janszky I, Andersson A, Svane B, Schenck-Gustafsson K. Physical activity and exercise performance predict long-term prognosis in middle-aged women surviving acute coronary syndrome. J Intern Med 2007;261:178-87. [4] Statistics NCfH. Health, United States, 2008. Hyattsville, MD: National Center for Health Statistics; 2009. [5] Karmisholt K, Gotzsche PC. Physical activity for secondary prevention of disease. Systematic reviews of randomised clinical trials. Dan Med Bull 2005;52:90-4. [6] Fletcher GF, Balady G, Blair SN, et al. Statement on exercise: benefits and recommendations for physical activity programs for all Americans. A statement for health professionals by the Committee on Exercise and Cardiac Rehabilitation of the Council on Clinical Cardiology, American Heart Association. Circulation 1996;94:857-62. [7] Fletcher GF, Balady GJ, Amsterdam EA, et al. Exercise standards for testing and training: a statement for healthcare professionals from the American Heart Association. Circulation 2001;104:1694-740. [8] Pate RR, Pratt M, Blair SN, et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402-7. [9] Scrutinio D, Bellotto F, Lagioia R, Passantino A. Physical activity for coronary heart disease: cardioprotective mechanisms and effects on prognosis. Monaldi Arch Chest Dis 2005;64:77-87. [10] Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med 2000;342:1163-70.
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