CORRESPONDENCE: LETTER TO THE EDITOR
Noninvasive Risk Assessment Early After a Myocardial InfarctionAre We Looking at the Right Indicators?
Sandeep Goyal, MD and
Sujeeth R. Punnam, MD*
* Department of Internal Medicine, Division of Cardiology, A-205 Clinical Center, Michigan State University, East Lansing, Michigan 48823 (Email: punnam{at}msu.edu).
Exner et al. (1) looked at the role of combined assessment of autonomic tone plus cardiac electrical substrate as markers of predicting long-term mortality in evaluating 322 patients who survived myocardial infarction (MI) but with left ventricular (LV) dysfunction. We have 3 concerns about this study. First, the authors fail to report the incidence of nonsustained ventricular tachycardia in study patients. Nonsustained ventricular tachycardia has already been proved as an electric substrate and an indicator of high mortality in patients with LV dysfunction (2). Second, there is no information on the use of antiarrhythmic drugs in study patients, which might very well affect the outcome. Third, most patients in the study (81%) underwent revascularization by percutaneous coronary intervention, and the authors reported a significant increase in left ventricular ejection fraction over the initial 2 months after MI. Distal embolization is a known complication of percutaneous coronary intervention. Distal embolization is a phenomenon in which macro emboli from the original lesion migrate distally, causing micro-infarcts leading to inadequate flow at the tissue level despite reopened epicardial coronary artery. It is related to reduced myocardial reperfusion and a poor prognosis (3), but the authors did not report any data about it. These micro-infarcts could be playing a role in some of the unexplained increase in mortality in post-MI patients, even though the left ventricular ejection fraction is improved significantly. There is a need to assess the effect of these confounding variables, to truly determine the most accurate and clinically feasible noninvasive markers to predict long-term prognosis after MI. A study that combines clinical, electrophysiological, and imaging (echocardiography and angiography) data to assess the long-term prognosis after MI is warranted.
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1. Exner DV, Kavanagh KM, Slawnych MP, et al. Noninvasive risk assessment early after a myocardial infarction: the REFINE study J Am Coll Cardiol 2007;50:2275-2284.[Abstract/Free Full Text]2. Moss AJ, Hall WJ, Cannom DS, et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia N Engl J Med 1996;335:1933-1940.[Abstract/Free Full Text] 3. Henriques JPS, Zijlstra F, Ottervanger JP, et al. Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction Eur Heart J 2002;23:1112-1117.[Abstract/Free Full Text]
Related Article
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Reply
- Derek V. Exner on behalf of the REFINE Investigators
J. Am. Coll. Cardiol. 2008 51: 1910-1911.
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