Screening of extra-coronary arteriopathy with magnetic resonance angiography in patients with spontaneous coronary artery dissection: a single-centre experience.

BACKGROUND: Current consensus recommends extended vascular investigation in patients with spontaneous coronary artery dissection (SCAD). We here report our experience with the use of magnetic resonance angiography (MRA) for screening extra-coronary arteriopathy in patients presenting with SCAD. METHODS: Patients presenting with SCAD in a Spanish centre underwent prospective contrast-enhanced MRA to assess the cephalic and abdominopelvic arterial territories. Fibromuscular dysplasia (FMD) was diagnosed following European consensus criteria. Other vascular abnormalities were recorded separately. Two vascular radiologists supervised the acquisitions and independently analysed the results for all cases. RESULTS: Forty patients with SCAD [mean age 50.9±8.6 years, 90% (n=36) women] were included in the study, 12 patients declined to participate and 5 were excluded (metallic implanted devices). All enrolled patients underwent the screening protocol without complications. MRA demonstrated at least one extra-coronary vascular abnormality in 16 patients (40%): 5 (12.5%) were diagnosed with FMD, 6 (15%) showed arterial tortuosity, 3 (7.5%) had non-FMD focal stenoses, and 2 (5%) were found to have small aneurysms at the celiac trunk and splenic artery. No intracranial aneurysms were detected. At a mean follow-up of 4±3 years from the index episode, two cases experienced SCAD recurrences, one in a patient with FMD and the other one in a patient with arterial tortuosity. No deaths or strokes occurred. CONCLUSIONS: Systematic extended vascular study with MRA was feasible and demonstrated associated extra-coronary arteriopathy in a substantial proportion of patients presenting with SCAD; however, none required additional intervention or led to vascular events. MRA, being a radiation-free modality, may be the preferred method for screening extracoronary arteriopathy in SCAD, a condition primarily affecting young and middle-age women sensitive to the risks of radiation.

Nitric oxide from mononuclear cells may be involved in platelet responsiveness to aspirin.

BACKGROUND: Several mechanisms have been proposed to explain why some platelets have a reduced response to aspirin (ASA). Among them, it was reported an increased circulating level of vitamin-D-binding protein (DBP). In addition, nitric oxide (NO) released from mononuclear cells was involved in the antiplatelet effects of ASA. The aim was to analyse the relationship between platelet response to ASA and both NO generation and vitamin-D-binding protein content in mononuclear cells. MATERIALS AND METHODS: Mononuclear cells were obtained from patients with stable coronary artery disease that were divided by a platelet functionality test (PFA-100) as ASA-sensitive (n=23) and ASA resistant (n=27). RESULTS: Both the release of NO (determined by nitrite+nitrate concentration) and the expression of endothelial-type NO synthase (eNOS) were higher in mononuclear cells from ASA sensitive as compared with those from ASA-resistant patients. There was a positive correlation between either the release of NO and the expression of eNOS protein in mononuclear cells with the ability of ASA to inhibit platelet activity. DBP content in mononuclear cells was higher in ASA resistant than in ASA sensitive. The level of DBP content in mononuclear cells was negatively associated with the ability of ASA to inhibit platelets. However, in vitro experiments suggested that there was no association between DBP and NO production by mononuclear cells. CONCLUSIONS: Mononuclear cells from patients with platelets with lower responsiveness to ASA showed a reduced ability to produce NO.

Platelet content of nitric oxide synthase 3 phosphorylated at Serine 1177 is associated with the functional response of platelets to aspirin.

OBJECTIVE: To analyse if platelet responsiveness to aspirin (ASA) may be associated with a different ability of platelets to generate nitric oxide (NO). PATIENTS/METHODS: Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26) and ASA-resistant (n = 24) using a platelet functionality test (PFA-100). RESULTS: ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate) than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3) was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2) isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position -786 (T(-786) → C) in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser)(1177), an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser(1177) phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018) of NOS3 phosphorylation at Ser(1177). On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser(1177). During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. CONCLUSIONS: Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser(1177).