(Circulation. 1998;98:1824-1827.)
© 1998 American Heart Association, Inc.
Natural History of Infarct-Related Lesions
Fernando Alfonso, MD, PhD, FESC
Cardiopulmonary Department Hospital Universitario, San
Carlos,
Madrid, Spain
To the Editor:
We read with great interest the elegant study of Van Belle et
al1 describing the natural history of the
infarct-related lesion using coronary angioscopy. They found
that most patients had yellow plaques (79%) and thrombus (77%)
without appreciable changes in these features according to the elapsed
time from the infarction. They concluded that infarct-related lesions
require more than a month to heal, or in other words, that during this
time most patients still have unstable plaques. They further suggested
that these findings could explain the unique, untoward behavior of
recently infarcted lesions either spontaneously or after
percutaneous treatment. We wish to draw attention to
some methodological aspects of their report. First, the true "natural
history" of the pathological substrate of the infarct-related lesion
would require serial angioscopic examinations (with each patient being
his/her own control), with the obvious ethical implications.
Alternatively, a much larger cohort of patients would have been
required to derive definitive insights about the potential influence of
the elapsed time from the infarction on the angioscopic data. Second,
only 7% of the patients had postinfarction angina, and no information
was provided concerning other clues for ischemia. Therefore,
most patients underwent the procedure on anatomic grounds alone. In
this context, the reasons to perform cardiac
catheterization early or late (24 hours to 4 weeks)
after infarction could imply a selection bias that may have influenced
the results. Finally, any explanation for the "unique adverse
behavior" of the infarct-related lesions will necessarily require
that the angioscopic features of these patients are different from
those of other patients with unstable angina and a more benign course.
Furthermore, a control group seems especially necessary when the
reported incidence of yellow plaque and thrombus was rather similar to
that found in other patients with unstable
angina.2 3
In a previous study,4 we analyzed
the angioscopic characteristics of patients with recurrent
ischemia (24 hours to 4 weeks) after infarction. Compared with
other patients with unstable angina (but without previous infarction),
patients with postinfarction ischemia had similar plaque
characteristics (yellow plaque 80% versus 84%) but a higher incidence
of associated thrombi (95% versus 68%), mainly at the expense of
protruding occlusive thrombi. Although the simplified angioscopic
classification used in the 2 studies was slightly different, it is of
interest that the results of Van Belle et al1
fall in the middle of our 2 groups of patients.4
This further corroborates the suggestion4 that
the presence of a red thrombus (mainly if occlusive) plays a
significant pathogenic role in the recurrence of
ischemia after myocardial infarction.
References
-
Van Belle E, Lablanche J-M, Bauters C, Renaud N,
McFadden EP, Bertrand ME. Coronary angioscopic findings in the
infarct-related vessel within 1 month of acute myocardial infarction:
natural history and the effect of thrombolysis.
Circulation. 1998;97:26–33.
-
Alfonso F, Goicolea J, Hernandez R, Goncalves M,
Segovia J, Bañuelos C, Zarco P, Macaya C. Angioscopic findings of
coronary angioplasty of coronary occlusions.
J Am Coll Cardiol. 1995;26:135–141.
-
deFeyter PJ, Ozaki P, Baptista J, Escaned J, Dimario
C, deJaegere PPT, Serruys PW, Roelandt JR. Ischemia-related
lesion characteristics in patients with stable and unstable angina: a
study with intracoronary angioscopy and ultrasound.
Circulation. 1995;92:1408–1413.
-
Alfonso F, Segovia J, Goicolea J, Hernandez R,
Fernandez-Ortiz A, Bañuelos C, Macaya C. Angioscopic
characteristics of coronary narrowing in patients with
recurrent myocardial ischemia after myocardial infarction.
Am J Cardiol. 1997;79:1394–1396.
Response
Eric Van Belle, MD, PhD;
Jean-Marc Lablanche, MD;
Christophe Bauters, MD;
Nathalie Renaud, MD;
Eugène P. McFadden, MRCPI;
; Michel E. Bertrand, MD
Service de Cardiologie B et Hémodynamique,
Hôpital Cardiologique,
Lille, France
We welcome the opportunity to respond to the letter of Dr
Alfonso regarding our recent article, in which we showed that the
majority of infarct-related lesions had angioscopic evidence of
instability even when studied 1 month after myocardial
infarction.1
We agree with Dr Alfonso that the ideal approach to determine the
"natural history" of the infarct-related lesion would be to perform
serial angioscopic studies in a cohort of patients. However, as he
points out, this would be difficult to justify on ethical
grounds.
Second, as we stated in our article, our institutional policy
during the period of the study was to perform diagnostic
catheterization after myocardial infarction and to
perform ad hoc angioplasty in those patients with suitable
anatomy. The findings of our study in such unselected patients
cannot therefore be extrapolated to a population in whom the
indications for angiography are more restrictive. However, we do not
believe that the timing of angiography had a significant influence on
our findings, because the major message of the article was that even
when angioscopy was performed 1 month after infarction, there was a
high incidence of angioscopic "instability."
Finally, we agree that the presence of protruding red thrombi
seems to be an important indicator of plaque instability, as suggested
by the study performed by Dr Alfonso et al.2 In
fact, in a previous study,3 we showed that the
presence of protruding thrombi was a powerful predictor of late vessel
occlusion after balloon angioplasty. The results of our study, which
demonstrates a high prevalence of thrombus even in
asymptomatic patients after myocardial infarction, extends
the work of Dr Alfonso by demonstrating that clinical stability in the
postinfarction patient does not necessarily imply plaque stability.
The results of Dr Alfonso's study in conjunction with our
article emphasize the need for further research into the factors that
influence plaque instability, both in patients with unstable angina and
in those who have suffered a myocardial infarction.
References
-
Van Belle E, Lablanche JM, Bauters C, Renaud N,
McFadden EP, Bertrand ME. Coronary angioscopic findings in the
infarct-related vessel within 1 month of acute myocardial infarction:
natural history and the effect of thrombolysis.
Circulation. 1998;97:26–33.
-
Alfonso F, Segovia J, Goicolea J, Hernandez R,
Fernandez-Ortiz A, Banuelos C, Macaya C. Angioscopic characteristics of
coronary narrowing in patients with recurrent myocardial
ischemia after myocardial infarction. Am J
Cardiol. 1997;79:1394–1396.
-
Bauters C, Lablanche JM, McFadden EP, Hamon M,
Bertrand ME. Relation of coronary angioscopic findings at
coronary angioplasty to angiographic restenosis.
Circulation. 1995;92:2473–2479.
