Myocardial Injury After Noncardiac Surgery in Major General Surgical Patients a Prospective Observational Cohort Study.

OBJECTIVE: The objective of this study was to determine the prognostic relevance, clinical characteristics, and 30-day outcomes associated with myocardial injury after noncardiac surgery (MINS) in major general surgery patients. BACKGROUND: MINS has been independently associated with 30-day mortality after noncardiac surgery. The characteristics and prognostic importance of MINS in major general surgical patients have not been described. METHODS: This was an international prospective cohort study of a representative sample of 22,552 noncardiac surgery patients 45 years or older, of whom 4490 underwent major general surgery in 24 centers in 13 countries. All patients had fifth-generation plasma high-sensitivity troponin T (hsTnT) concentrations measured during the first 3 postoperative days. MINS was defined as a hsTnT of 20-65 ng/L and absolute change >5 ng/L or hsTnT ≥65 ng/L secondary to ischemia. The objectives of the present study were to determine (1) whether MINS is prognostically important in major general surgical patients, (2) the clinical characteristics of major general surgical patients with and without MINS, (3) the 30-day outcomes for major general surgical patients with and without MINS, and (4) the proportion of MINS that would have gone undetected without routine postoperative monitoring. RESULTS: The incidence of MINS in the major general surgical patients was 16.3% (95% CI, 15.3-17.4%). Thirty-day all-cause mortality in the major general surgical cohort was 6.8% (95% CI, 5.1%-8.9%) in patients with MINS compared with 1.2% (95% CI, 0.9%-1.6%) in patients without MINS ( P <0.01). MINS was independently associated with 30-day mortality in major general surgical patients (adjusted odds ratio 4.7, 95% CI, 3.0-7.4). The 30-day mortality was higher both among MINS patients with no ischemic features (ie, no ischemic symptoms or electrocardiogram findings) (5.4%, 95% CI, 3.7%-7.7%) and among patients with 1 or more clinical ischemic features (10.6%, 95% CI, 6.7%-15.8%). The proportion of major general surgical patients who had MINS without ischemic symptoms was 89.9% (95% CI, 87.5-92.0). CONCLUSIONS: Approximately 1 in 6 patients experienced MINS after major general surgery. MINS was independently associated with a nearly 5-fold increase in 30-day mortality. The vast majority of patients with MINS were asymptomatic and would have gone undetected without routine postoperative troponin measurement.

Normoxic low-altitude simulation (at 714 mmHg) improves limb blood perfusion in mice with hindlimb ischemia.

Humans have fewer cardiovascular events and improved outcomes after cardiovascular events when living at low and moderate altitudes (<3000 m) above sea level. We have previously shown that low-altitude simulation using reductions in barometric pressure enhances vasodilation ex vivo in arterial segments and reduces systemic vascular resistance in vivo and can also improve left ventricular function after a myocardial infarction. We hypothesize that low-altitude simulation could also improve hindlimb ischemia, a model of peripheral artery disease in humans. We performed femoral artery ligation to generate hindlimb ischemia in 3-month-old C57BL6 mice. Control group mice (n = 10) recovered at 754 mmHg (control) for 14 days. Treatment group mice (n = 15) were placed in a low-altitude simulation chamber (at 714 mmHg) to recover from surgery for 3-hours daily for 14 days. Hindlimb perfusion imaging using a laser Doppler line scanner was performed for all mice prior to the surgery, and then on days 1, 3, 7, and 14 post-surgery. At 2 weeks, ischemic reserve was significantly higher in the treatment group mice (0.50 ± 0.13 vs. 0.20 ± 0.06; p = 0.01). Treatment mice had higher functional scores and were able to walk better at two weeks. There was approximately three times less HIF1α found via western blotting and a small but statistically significant improvement of lectin perfusion in calf tissue of treatment mice. We conclude that low-altitude simulation improves blood perfusion in murine hindlimb ischemia. This approach may have therapeutic implications for humans with peripheral artery disease.

2018 Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology Focused Update of the Guidelines for the Use of Antiplatelet Therapy.

Antiplatelet therapy (APT) has become an important tool in the treatment and prevention of atherosclerotic events, particularly those associated with coronary artery disease. A large evidence base has evolved regarding the relationship between APT prescription in various clinical contexts and risk/benefit relationships. The Guidelines Committee of the Canadian Cardiovascular Society and Canadian Association of Interventional Cardiology publishes regular updates of its recommendations, taking into consideration the most recent clinical evidence. The present update to the 2011 and 2013 Canadian Cardiovascular Society APT guidelines incorporates new evidence on how to optimize APT use, particularly in situations in which few to no data were previously available. The recommendations update focuses on the following primary topics: (1) the duration of dual APT (DAPT) in patients who undergo percutaneous coronary intervention (PCI) for acute coronary syndrome and non-acute coronary syndrome indications; (2) management of DAPT in patients who undergo noncardiac surgery; (3) management of DAPT in patients who undergo elective and semiurgent coronary artery bypass graft surgery; (4) when and how to switch between different oral antiplatelet therapies; and (5) management of antiplatelet and anticoagulant therapy in patients who undergo PCI. For PCI patients, we specifically analyze the particular considerations in patients with atrial fibrillation, mechanical or bioprosthetic valves (including transcatheter aortic valve replacement), venous thromboembolic disease, and established left ventricular thrombus or possible left ventricular thrombus with reduced ejection fraction after ST-segment elevation myocardial infarction. In addition to specific recommendations, we provide values and preferences and practical tips to aid the practicing clinician in the day to day use of these important agents.

Pyruvate dehydrogenase inhibition by the inflammatory cytokine TNFα contributes to the pathogenesis of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced proliferation and suppressed apoptosis of pulmonary artery smooth muscle cells (PASMC). This apoptosis resistance is characterized by PASMC mitochondrial hyperpolarization [in part, due to decreased pyruvate dehydrogenase (PDH) activity], decreased mitochondrial reactive oxygen species (mROS), downregulation of Kv1.5, increased [Ca(++)](i), and activation of the transcription factor nuclear factor of activated T cells (NFAT). Inflammatory cells are present within and around the remodeled arteries and patients with PAH have elevated levels of inflammatory cytokines, including tumor necrosis factor-α (TNFα). We hypothesized that the inflammatory cytokine TNFα inhibits PASMC PDH activity, inducing a PAH phenotype in normal PASMC. We exposed normal human PASMC to recombinant human TNFα and measured PDH activity. In TNFα-treated cells, PDH activity was significantly decreased. Similar to exogenous TNFα, endogenous TNFα secreted from activated human CD8(+) T cells, but not quiescent T cells, caused mitochondrial hyperpolarization, decreased mROS, decreased K(+) current, increased [Ca(++)](i), and activated NFAT in normal human PASMC. A TNFα antibody completely prevented, while recombinant TNFα mimicked the T cell-induced effects. In vivo, the TNFα antagonist etanercept prevented and reversed monocrotaline (MCT)-induced PAH. In a separate model, T cell deficient rats developed less severe MCT-induced PAH compared to their controls. We show that TNFα can inhibit PASMC PDH activity and induce a PAH phenotype. Our work supports the use of anti-inflammatory therapies for PAH.