Assessment of residual thrombus burden in patients with ST-segment elevation myocardial infarction undergoing bivalirudin versus unfractionated heparin infusion: The MATRIX (minimizing adverse hemorrhagic events by transradial access site and angioX) OCT study.

BACKGROUND: Residual stent strut thrombosis after primary percutaneous coronary intervention (PCI), negatively affects myocardial perfusion, may increase stent thrombosis risk, and it is associated with neointima hyperplasia at follow-up. OBJECTIVES: To study the effectiveness of any bivalirudin infusion versus unfractionated heparin (UFH) infusion in reducing residual stent strut thrombosis in patients with ST-elevation myocardial infarction (STEMI). METHODS: Multi-vessel STEMI patients undergoing primary PCI and requiring staged intervention were selected among those randomly allocated to two different bivalirudin infusion regimens in the MATRIX (Minimizing Adverse Haemorrhagic Events by TRansradial Access Site and angioX) Treatment-Duration study. Those receiving heparin only were enrolled into a registry arm. Optical coherence tomography (OCT) of the infarct-related artery was performed at the end of primary PCI and 3-5 days thereafter during a staged intervention. The primary endpoint was the change in minimum flow area (ΔMinFA) defined as (stent area + incomplete stent apposition [ISA] area) - (intraluminal defect + tissue prolapsed area) between the index and staged PCI. RESULTS: 123 patients in bivalirudin arm and 28 patients in the UFH arm were included. Mean stent area, percentage of malapposed struts, and mean percent thrombotic area were comparable after index or staged PCI. The ΔMinFA in the bivalirudin group was 0.25 versus 0.05 mm2 in the UFH group, which resulted in a between-group significant difference of 0.36 [95% CI: (0.05, 0.71); p = .02]. This was mostly related to a decrease in tissue protrusion in the bivalirudin group (p = .03). There was a trend towards more patients in the bivalirudin group who achieved a 5% difference in the percentage of OCT frames with the area >5% (p = .057). CONCLUSIONS: The administration of bivalirudin after primary PCI significantly reduces residual stent strut thrombosis when compared to UFH. This observation should be considered hypothesis-generating since the heparin-treated patients were not randomly allocated.

Impact of Sex on Comparative Outcomes of Radial Versus Femoral Access in Patients With Acute Coronary Syndromes Undergoing Invasive Management: Data From the Randomized MATRIX-Access Trial.

OBJECTIVES: This study sought to assess whether transradial access (TRA) compared with transfemoral access (TFA) is associated with consistent outcomes in male and female patients with acute coronary syndrome undergoing invasive management. BACKGROUND: There are limited and contrasting data about sex disparities for the safety and efficacy of TRA versus TFA for coronary intervention. METHODS: In the MATRIX (Minimizing Adverse Haemorrhagic Events by TRansradial Access Site and Systemic Implementation of angioX) program, 8,404 patients were randomized to TRA or TFA. The 30-day coprimary outcomes were major adverse cardiovascular and cerebrovascular events (MACCE), defined as death, myocardial infarction, or stroke, and net adverse clinical events (NACE), defined as MACCE or major bleeding. RESULTS: Among 8,404 patients, 2,232 (26.6%) were women and 6,172 (73.4%) were men. MACCE and NACE were not significantly different between men and women after adjustment, but women had higher risk of access site bleeding (male vs. female rate ratio [RR]: 0.64; p = 0.0016), severe bleeding (RR: 0.17; p = 0.0012), and transfusion (RR: 0.56; p = 0.0089). When comparing radial versus femoral, there was no significant interaction for MACCE and NACE stratified by sex (pint = 0.15 and 0.18, respectively), although for both coprimary endpoints the benefit with TRA was relatively greater in women (RR: 0.73; p = 0.019; and RR: 0.73; p = 0.012, respectively). Similarly, there was no significant interaction between male and female patients for the individual endpoints of all-cause death (pint = 0.79), myocardial infarction (pint = 0.25), stroke (pint = 0.18), and Bleeding Academic Research Consortium type 3 or 5 (pint = 0.45). CONCLUSIONS: Women showed a higher risk of severe bleeding and access site complications, and radial access was an effective method to reduce these complications as well as composite ischemic and ischemic or bleeding endpoints.

Radiation Exposure and Vascular Access in Acute Coronary Syndromes: The RAD-Matrix Trial.

BACKGROUND: It remains unclear whether radial access increases the risk of operator or patient radiation exposure compared to transfemoral access when performed by expert operators. OBJECTIVES: This study sought to determine whether radial access increases radiation exposure. METHODS: A total of 8,404 patients, with or without ST-segment elevation acute coronary syndrome, were randomly assigned to radial or femoral access for coronary angiography and percutaneous intervention, and collected fluoroscopy time and dose-area product (DAP). RAD-MATRIX is a radiation sub-study of the MATRIX (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of AngioX) trial. We anticipated that 13 or more operators, each wearing a thorax (primary endpoint), wrist, and head (secondary endpoints) lithium fluoride thermoluminescent dosimeter, and randomizing at least 13 patients per access site, were needed to establish noninferiority of radial versus femoral access. RESULTS: Among 18 operators, performing 777 procedures in 767 patients, the noninferiority primary endpoint was not achieved (p value for noninferiority = 0.843). Operator equivalent dose at the thorax (77 µSv) was significantly higher with radial than femoral access (41 µSv; p = 0.02). After normalization of operator radiation dose by fluoroscopy time or DAP, the difference remained significant. Radiation dose at wrist or head did not differ between radial and femoral access. Thorax operator dose did not differ for right radial (84 µSv) compared to left radial access (52 µSv; p = 0.15). In the overall MATRIX population, fluoroscopy time and DAP were higher with radial compared to femoral access: 10 min versus 9 min (p < 0.0001) and 65 Gy·cm2 versus 59 Gy·cm2 (p = 0.0001), respectively. CONCLUSIONS: Compared to femoral access, radial access is associated with greater operator and patient radiation exposure when performed by expert operators in current practice. Radial operators and institutions should be sensitized towards radiation risks and adopt adjunctive radioprotective measures. (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of AngioX; NCT101433627).