Faculty Bibliography

The cardioprotective mechanisms of colchicine in patients with stable ischemic heart disease remain uncertain. We tested varying concentrations of colchicine on platelet activity in vitro and a clinically relevant 1.8-mg oral loading dose administered over 1 h in 10 healthy subjects. Data are shown as median [interquartile range]. Colchicine addition in vitro decreased light transmission platelet aggregation only at supratherapeutic concentrations but decreased monocyte- (MPA) and neutrophil-platelet aggregation (NPA) at therapeutic concentrations. Administration of 1.8 mg colchicine to healthy subjects had no significant effect on light transmission platelet aggregation but decreased the extent of MPA (28 % [22-57] to 22 % [19-31], p = 0.05) and NPA (19 % [16-59] to 15 % [11-30], p = 0.01), platelet surface expression of PAC-1 (370 mean fluorescence intensity (MFI) [328-555] to 333 MFI [232-407], p = 0.02) and P-selectin (351 MFI [269-492] to 279 [226-364], p = 0.03), and platelet adhesion to collagen (10.2 % [2.5-32.6] to 2.0 % [0.2-9.5], p = 0.09) 2 h post-administration. Thus, in clinically relevant concentrations, colchicine decreases expression of surface markers of platelet activity and inhibits leukocyte-platelet aggregation but does not inhibit homotypic platelet aggregation.

OPINION STATEMENT: Hyperglycemia in the setting of coronary revascularization is associated with increased adverse cardiovascular events in patients with or without diabetes mellitus. Data suggest that acute peri-procedural hyperglycemia causes an increase in inflammation, platelet activity, and endothelial dysfunction and is associated with plaque instability and infarct size. While peri-procedural blood glucose level is an independent predictor of adverse outcomes in patients undergoing coronary revascularization, treatment strategies remain uncertain. Randomized clinical trials of glucose-insulin-potassium infusions have consistently shown no benefit, while those comparing insulin therapy versus standard of care have demonstrated mixed results, likely due to the failure to reach euglycemia with these strategies. Although no glucose-lowering agent has been shown to be superior in peri-procedural glycemic control, the continuation of clinically prescribed long-acting glucose-lowering medications in patients with diabetes mellitus prior to coronary angiography and possible percutaneous coronary intervention may be the simplest and most effective approach to maintain euglycemia and decrease the associated increase in inflammation and platelet activity. However, alternative strategies such as therapies targeted at the underlying mechanism of harm (e.g., more potent anti-platelet therapy, anti-inflammatory therapy) should also be considered and warrant further investigation.

PURPOSE: Perfusion analysis from first-pass contrast enhancement kinetics requires modeling tissue contrast exchange. This study presents a new approach for numerical implementation of the tissue homogeneity model, incorporating flexible distance steps along the capillary (NTHf). METHODS: The proposed NTHf model considers contrast exchange in fluid packets flowing along the capillary, incorporating flexible distance steps, thus allowing more efficient and stable calculations of the transit of tracer through the tissue. We prospectively studied 8 patients (62 +/- 13 years old) with suspected CAD, who underwent first-pass perfusion CMR imaging at rest and stress prior to angiography. Myocardial blood flow (MBF) and myocardial perfusion reserve index (MPRI) were estimated using both the NTHf and the conventional adiabatic approximation of the TH models. Coronary artery lesions detected at angiography were clinically assigned to one of three categories of stenosis severity ('insignificant', 'mild to moderate' and 'severe') and related to corresponding myocardial territories. RESULTS: The mean MBF (ml/g/min) at rest/stress and MPRI were 0.80 +/- 0.33/1.25 +/- 0.45 and 1.68 +/- 0.54 in the insignificant regions, 0.74 +/- 0.21/1.09 +/- 0.28 and 1.54 +/- 0.46 in the mild to moderate regions, and 0.79 +/- 0.28/0.63 +/- 0.34 and 0.85 +/- 0.48 in the severe regions, respectively. The correlation coefficients of MBFs at rest/stress and MPRI between the NTHf and AATH models were r = 0.97/0.93 and r = 0.91, respectively. CONCLUSIONS: The proposed NTHf model allows efficient quantitative analysis of the transit of tracer through tissue, particularly at higher flow. Results of initial application to MRI of myocardial perfusion in CAD are encouraging.

The aim of this study was to determine the diagnostic value of cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE), cine imaging, and resting first-pass perfusion (FPP) in the evaluation for ischemic (IC) versus nonischemic (NIC) cardiomyopathy in new-onset heart failure with reduced (