Clinical Investigation
Distal embolization during primary angioplasty: Histopathologic features and predictability

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Background

Distal embolization during primary percutaneous coronary interventions (PCIs) may affect myocardial reperfusion. We evaluated the prevalence and features of embolization during primary PCI and its relationship with clinical and angiographic variables.

Methods

Forty-six consecutive patients with acute myocardial infarction underwent primary PCI with a filter-based distal protection device. Histopathologic analysis was performed on retrieved embolic fragments, assessing the presence and relative amount of fibrin, necrosis, lipid droplets, collagen, mucopolysaccharides, and leukocytes, as well as the total debris volume. Such variables were related to baseline clinical and angiographic variables.

Results

Embolic material was recovered in 41 (89%) of 46 cases, with a mean total debris volume of 1.2 ± 2.2 mm3. Prevalent histopathologic patterns were organized thrombus (47%), fresh thrombus (29%), and plaque fragments (24%). At multivariate analysis, none of the baseline clinical variables considered significantly predicted the total debris volume. Among angiographic variables, angiographic signs of high thrombus burden (cut-off coronary occlusion pattern or large intracoronary minus image) independently predicted the total debris volume at multivariate analysis (odds ratio 15.8, P < .005). Compared with its nonuse, abciximab did not affect the total number and the mean total volume of embolized material (15 ± 16 vs 10 ± 8 fragments, 1.5 ± 2.5 vs 1.0 ± 1.9 mm3, respectively, for both P > .20), or its qualitative composition.

Conclusions

Distal embolization occurs in most patients during primary PCI and mainly consists of plaque fragments and partially organized thrombi, which are likely to be scarcely responsive to antiplatelet drugs. Baseline angiographic signs of a high thrombus burden are the only significant predictors of the extent of distal embolization.

Section snippets

Patient population

We included in this study 46 consecutive patients referred to our catheterization laboratory for ST-elevation acute myocardial infarction who underwent primary PCI. All patients gave written informed consent. Inclusion criteria were (a) presentation within 12 hours from the onset of symptoms; (b) chest pain lasting >30 minutes and resistant to nitrates; (c) ≥0.2 mV ST-segment elevation in ≥2 contiguous leads on a 12-lead electrocardiogram; (d) infarct-related artery with a reference lumen

Patient characteristics and procedural results

Baseline clinical and angiographic characteristics of the entire population are summarized in Table I, Table II.

Procedural success was obtained in 45 (98%) of 46 patients. In 6 patients, the FilterWire delivery, initially unsuccessful, was achieved after insertion of a “buddy” wire to reduce vessel tortuosity; in 4 patients, predilatation with a 1.5-mm balloon was also necessary. Blinded positioning of the FilterWire because of persistent TIMI grade 0 flow occurred in 6 (13%) cases; filter

Discussion

The main findings of the present study are that (1) multiple distal embolization is a very common event during primary PCI, and its extent can be predicted by the angiographic features of the target lesion; and (2) the bulk of the embolic debris is represented by organizing thrombus and/or plaque fragments rather than fresh thrombus.

Embolization has long been considered an uncommon event during PCI. Only in patients with degenerated saphenous vein grafts has embolization been thought to be

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