Original ArticleFinal Myocardial Blush Grade Predicts Troponin I Elevation in Unstable Angina Patients Undergoing Percutaneous Intervention
Introduction
The timely restoration of coronary blood flow in patients with acute coronary syndromes is a primary objective for interventional cardiologists.1 The definition of procedural success has traditionally related, in part, to the restoration of TIMI 3 flow in the culprit vessel.2, 3 However, rather than TIMI flow, it is increasingly recognized that microvascular perfusion, downstream of the epicardial vessel, may be of more importance with regard to myocardial salvage and long term outcome.4 Myocardial blush grade (MBG) is a simple, easily performed angiography based technique for evaluating microvascular cardiac perfusion.5 It has been extensively studied in the setting of acute myocardial infarction treated with thrombolytic therapy6 and primary angioplasty.7 Patients showing improved final myocardial blush grade have reduced infarct size as judged by cardiac enzyme release,7 lower ejection fraction5, 8 and reduced mortality.5, 9
Though there are limited data for patients presenting with non-ST elevation myocardial infarction,10 there are currently no blush data for patients presenting with unstable angina without initial troponin I elevation. We therefore studied a cohort of unstable angina patients presenting at our institution who underwent early coronary angioplasty and stenting to evaluate the impact of final myocardial blush grade on clinical outcome.
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Study Population
From January 1999 to April 2001, 372 consecutive patients (266 males) presenting to our institution with unstable angina, underwent coronary intervention to the culprit lesion. Unstable angina was defined as typical retrosternal chest discomfort occurring for at least 15 min in the absence of admission troponin I elevation with or without electrocardiographic changes of ischaemia. No patients had a pre-procedural troponin I elevation to differentiate these patients from non-ST elevation
Baseline Demographic Data
There was no difference in baseline characteristics with respect to final myocardial blush grades (Table 1). The prevalence of coronary risk factors and previous history of coronary revascularisation were similar between blush grades. There was no difference in mean age between groups.
Angiographic Data
The left anterior descending artery was most frequently intervened upon (168/372) and comparatively few saphenous vein graft interventions were performed (27/372) (Table 2). Angiographic success was achieved in
Discussion
Assessment of myocardial blush grade in acute coronary syndrome patients presenting with acute myocardial infarction is a simple angiographic technique for predicting outcomes.5 There are considerable data that tissue myocardial perfusion predicts outcomes in presenting with ST elevation myocardial infarction.5, 6, 7 More recently, myocardial blush assessment has been expanded to patients presenting with non-ST elevation MI in whom post-procedural troponin elevation was associated with impaired
Acknowledgment
The authors wish to acknowledge the work of Marisa Madigan who assisted in the collection of follow up data for patients in the study.
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