Acute anterior myocardial infarction: increased dye intensity in the myocardial risk area after coronary angioplasty is associated with reduction of diastolic volumes.

Abstract

Background: Myocardial perfusion in the risk area during the acute phase of myocardial infarction has been extensively investigated over the last few years. The so-called "no-reflow" or "low-reflow phenomenon" (absence of myocardial perfusion despite patency of the infarct-related coronary artery) was shown to correlate with worse postinfarction remodeling, in particular when myocardial contrast echocardiography was used. The aim of this study was to determine, during routine coronary angiography performed before and after coronary angioplasty (PTCA) during the acute phase of myocardial infarction, the existence of the no-reflow phenomenon and its relation with ventricular remodeling, by evaluating the dye video density in the myocardial risk area. This confirmation by a different diagnostic technique may serve to highlight the role of myocardial perfusion as an index of prognosis in the clinical setting of acute myocardial infarction.

Methods: Twenty-six patients (23 males, 3 females, mean age 57 +/- 8.7 years) who underwent either rescue (n = 11, 42.3%) or primary PTCA, according to clinical indications, of the left anterior descending coronary artery during an acute anterior myocardial infarction and who did not have stenosis of the left circumflex or right coronary artery, were retrospectively selected from a 6 year intake. The extent of coronary stenosis was assessed using biplane quantitative coronary angiography, while end-diastolic and end-systolic volume indexes, together with regional wall motion, were computed from echocardiography performed in the first 24 hours and at 6 months. Patients were subdivided into two groups on the basis of dye video intensity in the risk area, as assessed from images obtained during left main coronary artery injections before and immediately after PTCA. It was used a subtraction technique (Group A: increased video intensity, n = 12; Group B: no change, n = 14), assuming that higher peak intensity reflects greater myocardial blood volume. Three patients in Group B with ineffective PTCA were excluded, so that the final number of considered patients was 11.

Results: The distribution of rescue PTCA was similar in the two groups (7 in Group A vs 3 in Group B, p = 0.13) as were clinical characteristics and therapeutic regimen. There was a significant time * group interaction for end-diastolic volumes (-4.6 +/- 23% in Group A vs +22 +/- 22% in Group B, p = 0.029), whereas end-systolic volumes showed a tendency to greater dilation in Group B (+19 +/- 28% vs +0.9 +/- 31% in Group A), although this difference was not significant (p = 0.27). No interaction was evident for increase in the vessel area (+46 +/- 12.5% in Group A vs +43.2 +/- 13.6% in Group B, p = 0.99), or for extent of regional dysfunction (+3.08 +/- 10.9 chords in Group A vs -2.5 +/- 9.5 chords in Group B, p = 0.50).

Conclusions: The detection of myocardial blood volume in the risk area using dye video intensity during left main dye contrast injection, is useful to distinguish whether there is improved perfusion at the muscular level, following successful angioplasty of the infarct-related coronary artery. Lack of improved myocardial perfusion has an adverse effect on left ventricular volumes independently of coronary stenosis resolution and regional wall motion changes in the time.