Adjunctive Thrombectomy in Primary Percutaneous Intervention for Acute Myocardial Infarction

Primary percutaneous coronary intervention (PCI) has become the favored reperfusion strategy in acute ST-segment elevation myocardial infarction. Lower post-PCI myocardial perfusion grade, no-reflow and even drug-eluting stent thrombosis have been related to the presence of intracoronary thrombus. Adjunctive thrombectomy refers to procedures and devices that remove thrombotic material from the infarction-related artery, in theory, before distal embolization can occur. There is substantial variability between randomized controlled trials of thrombectomy in primary PCI with regards to tested devices, procedural characteristics, adjuvant medical regimen and examined outcomes. As a general statement, improvements in myocardial perfusion endpoints do not translate into reductions in clinical outcomes. Yet, an increasing number of trials with a longer follow-up reported benefits arising late after the index myocardial infarction. Simple aspiration catheters may also produce better outcomes than devices that fragment the thrombus before aspirating debris. Clinical or angiographic variables which best predict benefits from the use of thrombectomy remain to be defined. The aim of this review is to provide perspective on the conclusions of available trials and meta-analysis of adjunctive thrombectomy in acute myocardial infarction. Targets for future studies are discussed.974E91E10

Quantification of Extracellular Matrix Expansion by CMR in Infiltrative Heart Disease

OBJECTIVES The aim of this study was to perform direct quantification of myocardial extracellular volume fraction (ECF) with T1-weighted cardiac magnetic resonance (CMR) imaging in patients suspected to have infiltrative heart disease. BACKGROUND Infiltrative heart disease refers to accumulation of abnormal substances within the myocardium. Qualitative assessment of late gadolinium enhancement (LGE) remains the most commonly used method for CMR evaluation of patients suspected with myocardial infiltration. This technique is widely available and can be performed in a reproducible and standardized manner. However, the degree of extracellular matrix expansion due to myocardial infiltration in the intercellular space has, to date, not been amenable to noninvasive quantification with LGE. METHODS We performed 3-T CMR in 38 patients (mean age 68 +/- 15 years) who were referred for assessment of infiltrative heart disease and also in 9 healthy volunteers as control subjects. The T1 quantification by Look-Locker gradient-echo before and after contrast determined segmental myocardial partition coefficients. The ECF was obtained by referencing the tissue partition coefficient for gadolinium to the plasma volume fraction in blood, derived from serum hematocrit. Cine CMR and LGE imaging in matching locations were also performed. RESULTS Seventeen patients (45%) had cardiac amyloidosis (CA) (biopsy-confirmed or clinically highly probable), 20 (53%) had a non-amyloid cardiomyopathy, and 1 had lysosomal storage disease. Median global ECF was substantially higher in CA patients (0.49) compared with non-amyloid cardiomyopathy patients (0.33, p < 0.0001) and volunteers (0.24, p = 0.0001). The ECF strongly correlated with visually assessed segmental LGE (r = 0.80, p < 0.0001) and LV mass index (r = 0.69, p < 0.0001), reflecting severity of myocardial infiltration. In patients with CA, ECF was highest in segments with LGE, although it remained elevated in segments without qualitative LGE. CONCLUSIONS The CMR ECF quantification identified substantial expansion of the interstitial space in patients with CA compared with volunteers. Further studies using this technique for diagnosis and assessment of the severity of myocardial infiltration are warranted. (J Am Coll Cardiol Img 2012;5:897-907) (C) 2012 by the American College of Cardiology Foundation59897907Bourse du Coeur 2009 scholarshipMontreal Heart Institute Foundation, Montreal, CanadaNational Institutes of Health [R01HL090634-01A1, R01HL091157]National Institutes of Health [R01HL090634-01A1, R01HL091157