Correspondence
Risk of Stroke after Myocardial Infarction
N Engl J Med 1997; 336:1916-1917June 26, 1997
- Article
To the Editor:
The report by Loh et al. (Jan. 23 issue),1 evaluating the association between left ventricular dysfunction and the risk of stroke in patients enrolled in the Survival and Ventricular Enlargement (SAVE) trial, raises important questions regarding the care of patients who have had myocardial infarctions. Two of the most important predictors of stroke are a history of stroke and transient ischemic attacks.2,3 Although the authors document the effect of a history of smoking, diabetes, and hypertension and of previous myocardial infarction, they do not comment on those two well-documented risk factors. I am curious whether their conclusions regarding the association of ventricular dysfunction and stroke would still hold if their analysis had controlled for a history of stroke and transient ischemic attacks.
3 ReferencesAndrew D. Michaels, M.D.
University of California, San Francisco, Medical Center, San Francisco, CA 94143-01241
Loh E ,St John Sutton M ,Wun C-CC , et al. Ventricular dysfunction and the risk of stroke after myocardial infarction. N Engl J Med 1997;336:251-257
Full Text | Web of Science | Medline2
Manolio TA ,Kronmal RA ,Burke GL ,O'Leary DH ,Price TR . Short-term predictors of incident stroke in older adults. Stroke 1996;27:1479-1486
CrossRef | Web of Science | Medline3
Aronow WS . Risk factors for geriatric stroke: identification and follow-up. Geriatrics 1990;45:37-40, 43
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To the Editor:
Loh et al. report that a decreased ejection fraction and older age are both independent predictors of an increased long-term risk of stroke after myocardial infarction. Besides the role of chronic atrial fibrillation as a known risk factor, which the authors address, a potential role of blood pressure should also be considered. Although the authors report that the proportion of patients with a history of hypertension did not differ significantly between the two groups, blood-pressure measurements would have been helpful in clarifying the role of this factor.
In a review of 45 prospective observational studies, the risk of stroke was strongly related to diastolic blood pressure.1 The relation did not tend to flatten out at levels below 80 mm Hg, and there was no threshold below which diastolic blood pressure was not positively associated with the risk of stroke. Most important, this positive relation was observed both in patients with and in those without preexisting coronary heart disease at base line.1
Pharmacologic treatment of hypertension plays a crucial part in the risk of long-term morbidity and mortality due to cerebrovascular accidents.2 In agreement with a recent study in a similar setting,3 the authors report that at the time of randomization approximately 40 percent of patients were receiving calcium-channel blockers and 35 percent were receiving beta-blockers. Both agents modulate blood pressure, but they have different prognostic value. Whereas a reduced risk of stroke in hypertensive patients treated with beta-blockers has been documented,2 calcium-channel blockers seem to increase overall mortality.3,4 Interestingly, calcium-channel blockers exert an antiplatelet effect, which might have been protective against embolic strokes. We believe that cardiovascular medications taken by the patients at randomization should have been included in the analysis.
4 ReferencesGiovanni Gambassi, M.D.
Brown University, Providence, RI 02912Pierugo Carbonin, M.D.
Roberto Bernabei, M.D.
Università Cattolica del Sacro Cuore, 00168 Rome, Italy1
Prospective Studies Collaboration
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Dahlof B ,Lindholm LH ,Hansson L ,Schersten B ,Ekbom T ,Wester PO . Morbidity and mortality in the Swedish Trial in Old Patients with Hypertension (STOP-Hypertension). Lancet 1991;338:1281-1285
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Soumerai SB ,McLaughlin TJ ,Spiegelman D ,Hertzmark E ,Thibault G ,Goldman L . Adverse outcomes of underuse of β-blockers in elderly survivors of acute myocardial infarction. JAMA 1997;277:115-121
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Pahor M ,Guralnik JM ,Corti M-C ,Foley DJ ,Carbonin P ,Havlik RJ . Long-term survival and use of antihypertensive medications in older persons. J Am Geriatr Soc 1995;43:1191-1197
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Author/Editor Response
The authors reply:
To the Editor: We agree with Dr. Michaels that a history of stroke or transient ischemic attacks is a risk factor for subsequent stroke after myocardial infarction. Unfortunately, in the SAVE trial, prerandomization data-base forms did not include this information. Accordingly, these variables could not be considered in the multivariate analysis.
We also agree with the comments of Gambassi et al., which emphasize the important role of antihypertensive agents such as beta-blockers in reducing the risk of stroke in patients with hypertension, regardless of the presence or absence of coronary heart disease. In our population of patients with left ventricular dysfunction after myocardial infarction and a mean prerandomization blood pressure of 113/70 mm Hg, we were not able to demonstrate that the nonrandomized use of beta-blockers, nitrates, or calcium-channel blockers affected the risk of subsequent stroke. Furthermore, in this blood-pressure range, even the randomly assigned use of the angiotensin-converting–enzyme inhibitor captopril did not reduce the risk of stroke. However, the nonrandomized use of beta-blockers was associated with an improvement in clinical outcomes (decreased risk of death from cardiovascular causes and of heart failure), to which the effect of angiotensin-converting–enzyme inhibitors was additive.1
1 ReferencesEvan Loh, M.D.
Hospital of the University of Pennsylvania, Philadelphia, PA 19104Lemuel A. Moyé, M.D., Ph.D.
University of Texas Health Science Center, Houston, TX 77030Marc A. Pfeffer, M.D., Ph.D.
Brigham and Women's Hospital, Boston, MA 021151
Vantrimpont P ,Rouleau JL ,Wun CC , et al. Additive beneficial effects of beta-blockers to angiotensin-converting enzyme inhibitors in the Survival and Ventricular Enlargement (SAVE) Study. J Am Coll Cardiol 1997;29:229-236
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