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Postinfarction risk profiling: Past, present and future considerations
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JACC Vol. 8, No.1 July 1986:50--1
Editorial Comment
Postinfarction Risk Profiling: Past, Present and Future Considerations* JOHN A. GILLESPIE, MD, FACC, ARTHUR J. MOSS, MD, FACC Rochester, New York
In this issue of the Journal, Fioretti et aI. (1) use a variety of clinical variables to predict survival after myocardial infarction. They also show the value of adding noninvasive stress testing to the clinical variables to enhance postinfarction risk stratification. The findings of Fioretti et al. are in close agreement with the recent risk stratification articles published by the Multicenter Postinfarction Program (MPIP) (2) and by the study group of the Multicenter Investigation for the Limitation of Infarct Size (3). In all three of these studies, clinical variables that reflect evidence of left ventricular dysfunction (prior myocardial infarction, advanced New York Heart Association functional classifications before admission, advanced Killip classification scores, rales and cardiomegaly) are the major determinants of mortality during the first and subsequent years after infarction. Role of exercise testing. Fioretti et aI. evaluated the predictive accuracy of noninvasive tests themselves. The nonsurvivors had a significantly lower radionuclide ejection fraction, a drop in blood pressure during exercise, a reduced maxiaml work load and more repetitive ventricular ectopic beats on 24 hour ambulatory electrocardiographic (Holter) monitoring than did those who survived I year follow-up. These findings are in close agreement with the data reported by the MPIP research group (2,4). It is interesting that both Fioretti et aI. and this research group found that ST segment depression or angina during exercise testing was not ~re dictive of subsequent mortality event. These observations are in direct contrast to the results reported from the Montreal Heart Institute by Theroux et aI.(5), found that angina
*Edilorials published in Journalofthe American.CollegeofCardio.logy reflect the views of the authors and do not necessanly represent the views of lACC or the American College of Cardiology. From the Department of Medicine, Highland Hospital an.d the Strong Memorial Hospital, University of Rochester School of Medicine and Den. . . tistry, Rochester, New York. Address for reprints: John A. Gillespie, MD, Cardiology Unit, HIghland Hospital, South Avenue & Bellevue Drive, Rochester, New York 14620.
© 1986 by the American College of Cardiology
and ST segment changes during exercise testing predicted mortality in the year after infarction. The explanation for this discrepancy between the findings of Fioretti and the research group MPIP and those of Theroux is not readily apparent, but preselection of the population by referral and a smaller sample size in the Canadian study may have contributed to an imprecise estimate of the risk.
Which noninvasive test predicts high risk in postinfarctlon patients? Fioretti et aI. makes an important contribution by evaluating which noninvasive tests were most helpful in improving risk stratifications once the clinical variables were allowed to exert their maximal influence in predicting outcome. A reasonable strategy has emerged. Basically, low level exercise testing should be performed on all postinfarction patients because it provides the most significant additional risk stratification information at the lowest cost when coupled with the clinical variables that are ordinarily obtained on all hospitalized patients. Exercise testing provides dynamic insight into global cardiac performance and, therefore, it reveals information about cardiac dynamics not uncovered by a spectrum of variables that are more static in nature. In patients who cannnot exercise, nuclear angiography and 24 hour ambulatory electrocardiographic monitoring provide useful risk profile information. With this approach, low and high risk patients can be easily identified. For example, approximately 50% of postinfarction patients have a I year mortality rate of less than 3%, and they are characterized simply by the absence of clinical variables indicative of left ventricular dysfunction and good performance on an exercise test. Krone et aI.(4) using similar variables (blood pressure response on the treadmill and absence of pulmonary congestion in the intensive care unit) also identified a large group (45% of postinfarction patients) with less than I% I year mortality. High risk patients make up about 10% of the postinfarction population, and their cinical profile is characterized by clinical and noninvasive test evidence of left ventricular dysfunction. What then is the role of nuclear angiography and 24 hour ambulatory electrocardiographic monitoring in the evaluation of the postinfarction patient? It would appear that these tests are most useful in patients who are unable to perform a stress test and in those with an equivocal risk profile. Although considerable progress has been made in the past 5 years in evaluating the physiologic risks of postinfarction patients, much remains to be done to further improve the science of clinical cardiology as it applies to this group of patients. At present, we do not have a good measure of either overt or silent myocardial ischemia, yet it is logical to assume that ischemic risk is at the heart of the major cardiac events that occur after myocardial infarction.
0735-1097/86/$3.50
GILLESPIE AND MOSS EDITORIAL COMMENT
JACC Vol. 8, No. ! July 1986:50--!
References I . Fioretti P, Brower RW, Simoons ML, et al. The relative value of clinical variables , bicycle ergometry, rest radionuclide ventriculography and ~4 hour ambulatory electrocardiographic monitoring at discharge to predict I year survival after myocardial infarction. J Am Coli Cardiol 1986;8:40--9. 2. The Multicenter Postinfarction Research Group. Risk stratification and survival after myocardial infarction. N Engl J Med 1983 ;309 :331 ~6. 3. Mukharji J , Rude R,Pooie K, et al. and the MILlS Study Group . Risk
51
factors for sudden death after acute myocardial infarction: two year follow-up . Am J Cardiol 1984;54:31-6. 4. Krone RJ, Gillespie lA , Weld FM, Miller JP, Moss AJ and Multicenter Postinfarction Research Group . Low-level exercise testing after myocardial infarction: usefulne ss in enhancing clinical risk stratification. Circulation 1985; 71: 80-9. 5. Therou x P, Wattrs D, Halphen C, Debaisieux 1, Mizgala H. Prognostic value of exercise testing soon after myocardial infarction. N Engl J Med 1979;301:341-5 ..
JACC Vol. 8, No.1 July 1986:50--1
Editorial Comment
Postinfarction Risk Profiling: Past, Present and Future Considerations* JOHN A. GILLESPIE, MD, FACC, ARTHUR J. MOSS, MD, FACC Rochester, New York
In this issue of the Journal, Fioretti et aI. (1) use a variety of clinical variables to predict survival after myocardial infarction. They also show the value of adding noninvasive stress testing to the clinical variables to enhance postinfarction risk stratification. The findings of Fioretti et al. are in close agreement with the recent risk stratification articles published by the Multicenter Postinfarction Program (MPIP) (2) and by the study group of the Multicenter Investigation for the Limitation of Infarct Size (3). In all three of these studies, clinical variables that reflect evidence of left ventricular dysfunction (prior myocardial infarction, advanced New York Heart Association functional classifications before admission, advanced Killip classification scores, rales and cardiomegaly) are the major determinants of mortality during the first and subsequent years after infarction. Role of exercise testing. Fioretti et aI. evaluated the predictive accuracy of noninvasive tests themselves. The nonsurvivors had a significantly lower radionuclide ejection fraction, a drop in blood pressure during exercise, a reduced maxiaml work load and more repetitive ventricular ectopic beats on 24 hour ambulatory electrocardiographic (Holter) monitoring than did those who survived I year follow-up. These findings are in close agreement with the data reported by the MPIP research group (2,4). It is interesting that both Fioretti et aI. and this research group found that ST segment depression or angina during exercise testing was not ~re dictive of subsequent mortality event. These observations are in direct contrast to the results reported from the Montreal Heart Institute by Theroux et aI.(5), found that angina
*Edilorials published in Journalofthe American.CollegeofCardio.logy reflect the views of the authors and do not necessanly represent the views of lACC or the American College of Cardiology. From the Department of Medicine, Highland Hospital an.d the Strong Memorial Hospital, University of Rochester School of Medicine and Den. . . tistry, Rochester, New York. Address for reprints: John A. Gillespie, MD, Cardiology Unit, HIghland Hospital, South Avenue & Bellevue Drive, Rochester, New York 14620.
© 1986 by the American College of Cardiology
and ST segment changes during exercise testing predicted mortality in the year after infarction. The explanation for this discrepancy between the findings of Fioretti and the research group MPIP and those of Theroux is not readily apparent, but preselection of the population by referral and a smaller sample size in the Canadian study may have contributed to an imprecise estimate of the risk.
Which noninvasive test predicts high risk in postinfarctlon patients? Fioretti et aI. makes an important contribution by evaluating which noninvasive tests were most helpful in improving risk stratifications once the clinical variables were allowed to exert their maximal influence in predicting outcome. A reasonable strategy has emerged. Basically, low level exercise testing should be performed on all postinfarction patients because it provides the most significant additional risk stratification information at the lowest cost when coupled with the clinical variables that are ordinarily obtained on all hospitalized patients. Exercise testing provides dynamic insight into global cardiac performance and, therefore, it reveals information about cardiac dynamics not uncovered by a spectrum of variables that are more static in nature. In patients who cannnot exercise, nuclear angiography and 24 hour ambulatory electrocardiographic monitoring provide useful risk profile information. With this approach, low and high risk patients can be easily identified. For example, approximately 50% of postinfarction patients have a I year mortality rate of less than 3%, and they are characterized simply by the absence of clinical variables indicative of left ventricular dysfunction and good performance on an exercise test. Krone et aI.(4) using similar variables (blood pressure response on the treadmill and absence of pulmonary congestion in the intensive care unit) also identified a large group (45% of postinfarction patients) with less than I% I year mortality. High risk patients make up about 10% of the postinfarction population, and their cinical profile is characterized by clinical and noninvasive test evidence of left ventricular dysfunction. What then is the role of nuclear angiography and 24 hour ambulatory electrocardiographic monitoring in the evaluation of the postinfarction patient? It would appear that these tests are most useful in patients who are unable to perform a stress test and in those with an equivocal risk profile. Although considerable progress has been made in the past 5 years in evaluating the physiologic risks of postinfarction patients, much remains to be done to further improve the science of clinical cardiology as it applies to this group of patients. At present, we do not have a good measure of either overt or silent myocardial ischemia, yet it is logical to assume that ischemic risk is at the heart of the major cardiac events that occur after myocardial infarction.
0735-1097/86/$3.50
GILLESPIE AND MOSS EDITORIAL COMMENT
JACC Vol. 8, No. ! July 1986:50--!
References I . Fioretti P, Brower RW, Simoons ML, et al. The relative value of clinical variables , bicycle ergometry, rest radionuclide ventriculography and ~4 hour ambulatory electrocardiographic monitoring at discharge to predict I year survival after myocardial infarction. J Am Coli Cardiol 1986;8:40--9. 2. The Multicenter Postinfarction Research Group. Risk stratification and survival after myocardial infarction. N Engl J Med 1983 ;309 :331 ~6. 3. Mukharji J , Rude R,Pooie K, et al. and the MILlS Study Group . Risk
51
factors for sudden death after acute myocardial infarction: two year follow-up . Am J Cardiol 1984;54:31-6. 4. Krone RJ, Gillespie lA , Weld FM, Miller JP, Moss AJ and Multicenter Postinfarction Research Group . Low-level exercise testing after myocardial infarction: usefulne ss in enhancing clinical risk stratification. Circulation 1985; 71: 80-9. 5. Therou x P, Wattrs D, Halphen C, Debaisieux 1, Mizgala H. Prognostic value of exercise testing soon after myocardial infarction. N Engl J Med 1979;301:341-5 ..