Correspondence
Dyspnea and Stress Testing
N Engl J Med 2006; 354:871-873February 23, 2006
- Article
To the Editor:
The article by Abidov et al. (Nov. 3 issue)1 identifies a high-risk group of patients undergoing myocardial-perfusion single-photon-emission computed tomography (SPECT). These patients have dyspnea but are otherwise asymptomatic, and they have a higher mortality than those with typical angina. In this article the authors have not reported the indication for myocardial-perfusion testing. It is important to know why these patients were undergoing the tests in the absence of chest pain. Usually such patients are undergoing preoperative evaluations or may have rhythm problems. I fear we might be dealing with a group of patients who were undergoing myocardial-perfusion testing for reasons that would make their risk of death differ from the risk among patients who undergo testing for chest pain, thus confounding the results. Further confirmation of these findings will therefore be necessary.
1 ReferencesShowkat A. Haji, M.D.
Tulane University Medical Center, New Orleans, LA 70112
showhaji@aol.com 1
Abidov A ,Rozanski A ,Hachamovitch R , et al. Prognostic significance of dyspnea in patients referred for cardiac stress testing. N Engl J Med 2005;353:1889-1898
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To the Editor:
In the study by Abidov et al., self-reported dyspnea identified patients at increased risk for death from cardiac causes and from any cause. Physical fitness and body-mass index were not assessed by the investigators. Physical activity and cardiorespiratory fitness are important independent determinants of mortality.1-3 Since dyspnea is a common sign of deconditioning4 (often due to the patient's obesity and lack of physical activity), the high mortality reported by the authors might be explained in part by low cardiorespiratory fitness in the analyzed population.
4 ReferencesFlorim Cuculi, M.D.
Paul Erne, M.D.
Kantonsspital Luzern, 6000 Lucerne, Switzerland
paul.erne@ksl. ch 1
Church TS ,LaMonte MJ ,Barlow CE ,Blair SN . Cardiorespiratory fitness and body mass index as predictors of cardiovascular disease mortality among men with diabetes. Arch Intern Med 2005;165:2114-2120
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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;156:832-841
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Wei M ,Kampert JB ,Barlow CE , et al. Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men. JAMA 1999;282:1547-1553
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Milani RV ,Lavie CJ ,Mehra MR . Cardiopulmonary exercise testing: how do we differentiate the cause of dyspnea? Circulation 2004;110:e27-e31
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To the Editor:
Abidov et al. report that patients presenting with dyspnea and referred for cardiac stress testing had an increased risk of death. In their discussion of potential explanations, the authors do not consider the possibility of dynamic functional mitral regurgitation. Their patients with dyspnea at presentation had a higher incidence of left ventricular dilatation and of systolic dysfunction than did patients with other or no symptoms. This combination may lead to incomplete closure of the mitral valve, through both leaflet restriction and reduced coapting force. In a series of 161 patients who underwent exercise echocardiography, we found that the exercise-induced increase in ischemic mitral regurgitation was greater in patients who stopped the exercise test because of dyspnea than in those who stopped because of fatigue (Figure 1Figure 1
Exercise-Induced Changes in the Effective Regurgitant Orifice Area and in the Transtricuspid Pressure Gradient in 161 Patients with Left Ventricular Systolic Dysfunction.). Furthermore, dynamic mitral regurgitation may contribute to acute pulmonary edema1 and is an independent determinant of increased mortality and of major cardiac events.2,3 What was the incidence of dyspnea induced by exercise in the subgroups studied by Abidov et al.? Did they analyze postexercise thallium uptake by the lungs, which is of prognostic importance?4
4 ReferencesLuc A. Piérard, M.D.
Patrizio Lancellotti, M.D.
University Hospital, 4000 Liege, Belgium
lpierard@chu.ulg. ac. be 1
Pierard LA ,Lancellotti P . The role of ischemic mitral regurgitation in the pathogenesis of acute pulmonary edema. N Engl J Med 2004;351:1627-1634
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Lancellotti P ,Troisfontaines P ,Toussaint A-C ,Pierard LA . Prognostic importance of exercise-induced changes in mitral regurgitation in patients with chronic ischemic left ventricular dysfunction. Circulation 2003;108:1713-1717
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Lancellotti P ,Gerard PL ,Pierard LA . Long-term outcome of patients with heart failure and dynamic mitral regurgitation. Eur Heart J 2005;26:1528-1532
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Gill JB ,Ruddy TD ,Newel JB , et al. Prognostic importance of thallium uptake by the lungs during exercise in coronary artery disease. N Engl J Med 1987;317:1486-1489
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To the Editor:
Among 20,572 patients evaluated by Abidov et al. for inclusion in their study, the 1735 patients (8.4 percent) who underwent coronary revascularization within 60 days after testing were excluded. The indications for coronary angiography or revascularization, however, were not discussed in the article. In the study population of 17,991 patients (those without coronary revascularization), did the 5042 patients (28.0 percent) with stress-induced ischemia undergo coronary angiography? What percentage of the patients who underwent coronary angiography had angiographically significant coronary-artery stenosis? Among the five groups defined on the basis of symptoms at presentation, what is the distribution of patients who underwent no coronary angiography despite stress-induced ischemia or those who underwent no coronary revascularization despite angiographically significant coronary-artery stenosis? The severity of stress-induced ischemia or findings on coronary angiography, as well as perfusion imaging, as analyzed in the accompanying editorial by Marwick,1 may be used to predict outcome in patients presenting with dyspnea.
1 ReferencesHisato Takagi, M.D., Ph.D.
Takayoshi Kato, M.D.
Yukihiro Matsuno, M.D., Ph.D.
Shizuoka Medical Center, Shizuoka 411-8611, Japan
kfgth973@ybb.ne. jp 1
Marwick TH . Dyspnea and risk in suspected coronary disease. N Engl J Med 2005;353:1963-1965
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To the Editor:
Dr. Abidov and coworkers, studying 17,991 patients, found that dyspnea at presentation identifies in otherwise asymptomatic patients an increased risk of death from any cause. However, the relationship between everyday shortness of breath and dyspnea during the exercise test is not evident from their study. Providing these data could yield important information about the significance of dyspnea that appears only when the patient is exercising under laboratory conditions. Dr. Phibbs and coworkers1 reported in 1968 that patients who never had shortness of breath “were surprised when they experienced distressing dyspnea during stress testing. After further questioning they often recalled similar dyspnea on exertion which they had simply accepted as a part of their normal way of life.” During the exercise test, 26.5 percent of their patients had only dyspnea at the time of ischemic change on the electrocardiogram.
1 ReferencesShlomo Stern, M.D.
Hebrew University of Jerusalem, 94592 Jerusalem, Israel
sh_stern@netvision.net. il 1
Phibbs B ,Holmes RW ,Lowe CR . Transient myocardial ischemia: the significance of dyspnea. Am J Med Sci 1968;256:210-221
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Author/Editor Response
Dr. Haji notes that patients with dyspnea may be referred for stress testing for reasons that would put these patients at higher risk for death. Since we found more morbidity among patients with dyspnea, this symptom may be an indicator, as Dr. Haji suggests, of a sicker constellation of patients. Preoperative assessment as a reason for testing was an independent predictor of mortality in our study, but after adjustment for this and other variables, dyspnea remained an independent predictor.
Regarding the assertion of Drs. Cuculi and Erne: we did in fact assess both body-mass index and exercise duration, a marker of physical fitness, but neither was a significant predictor of outcome in our final multivariable model. This finding is not incongruent with the observations of Cuculi and Erne but reflects the fact that common predictors of outcome in general populations often are not robust predictors of outcome in selected patient populations.1
Drs. Piérard and Lancellotti suggest that exercise-induced dynamic functional mitral regurgitation may have been a mechanism for inducing dyspnea in our patients on an ischemic basis. Although we cannot exclude this possibility for some of our patients, dyspnea was associated with increased mortality within all subgroups, including those unlikely to have such ischemic manifestation, such as patients who underwent vasodilator-induced rather than exercise-induced stress and those without stress-induced ischemia. We did not evaluate postexercise thallium uptake by the lungs, because we used technetium-99m (sestamibi) as our poststress radiotracer. The relationship between sestamibi uptake by the lungs and prognosis has not been well defined.
We agree with Takagi et al. that the severity of stress-induced ischemia and the results of coronary angiography (when indicated and available) may be used to complement the prediction of outcome among patients presenting with dyspnea. Furthermore, we previously have observed that the decision to perform catheterization in patients soon (<60 days) after stress testing is based on the results of SPECT and is ischemia-driven.2 We excluded such patients, since revascularization may have distorted the results of the multivariable analysis (i.e., patients with extensive ischemia would have improved outcomes because of revascularization).
Finally, Dr. Stern suggests that it may be useful to assess both everyday dyspnea and dyspnea that is observed during concomitant exercise testing. We agree. Along these lines, a recent long-term follow-up study showed heightened mortality among 2014 healthy middle-aged men who had impaired breathing during exercise testing.3
3 ReferencesAiden Abidov, M.D., Ph.D.
Cedars–Sinai Medical Center, Los Angeles, CA 90048Alan Rozanski, M.D.
St. Luke–Roosevelt Medical Center, New York, NY 10025Daniel S. Berman, M.D.
Cedars–Sinai Medical Center, Los Angeles, CA 90048
bermand@cshs.org 1
Klein J ,Chao SY ,Berman DS ,Rozanski A . Is `silent' myocardial ischemia really as severe as symptomatic ischemia? The analytical effect of patient selection biases. Circulation 1994;89:1958-1966
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Hachamovitch R ,Hayes SW ,Friedman JD , et al. Is there a referral bias against catheterization of patients with reduced left ventricular ejection fraction? Influence of ejection fraction and inducible ischemia on post-single-photon emission computed tomography management of patients without a history of coronary artery disease. J Am Coll Cardiol 2003;42:1286-1294
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Bodegard J ,Erikssen G ,Bjornholt JV ,Gjesdal K ,Liestol K ,Erikssen J . Reasons for terminating an exercise test provide independent prognostic information: 2014 apparently healthy men followed for 26 years. Eur Heart J 2005;26:1394-1401
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- Citing Articles (2)
