Effect of Out-of-Hospital Tranexamic Acid vs Placebo on 6-Month Functional Neurologic Outcomes in Patients With Moderate or Severe Traumatic Brain Injury

IMPORTANCE

Traumatic brain injury (TBI) is the leading cause of death and disability due to trauma. Early administration of tranexamic acid may benefit patients with TBI.

OBJECTIVE

To determine whether tranexamic acid treatment initiated in the out-of-hospital setting within 2 hours of injury improves neurologic outcome in patients with moderate or severe TBI.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, double-blinded, randomized clinical trial at 20 trauma centers and 39 emergency medical services agencies in the US and Canada from May 2015 to November 2017. Eligible participants (N = 1280) included out-of-hospital patients with TBI aged 15 years or older with Glasgow Coma Scale score of 12 or less and systolic blood pressure of 90 mm Hg or higher.

INTERVENTIONS

Three interventions were evaluated, with treatment initiated within 2 hours of TBI: out-of-hospital tranexamic acid (1 g) bolus and in-hospital tranexamic acid (1 g) 8-hour infusion (bolus maintenance group; n = 312), out-of-hospital tranexamic acid (2 g) bolus and in-hospital placebo 8-hour infusion (bolus only group; n = 345), and out-of-hospital placebo bolus and in-hospital placebo 8-hour infusion (placebo group; n = 309).

MAIN OUTCOMES AND MEASURES

The primary outcome was favorable neurologic function at 6 months (Glasgow Outcome Scale-Extended score >4 [moderate disability or good recovery]) in the combined tranexamic acid group vs the placebo group. Asymmetric significance thresholds were set at 0.1 for benefit and 0.025 for harm. There were 18 secondary end points, of which 5 are reported in this article: 28-day mortality, 6-month Disability Rating Scale score (range, 0 [no disability] to 30 [death]), progression of intracranial hemorrhage, incidence of seizures, and incidence of thromboembolic events.

RESULTS

Among 1063 participants, a study drug was not administered to 96 randomized participants and 1 participant was excluded, resulting in 966 participants in the analysis population (mean age, 42 years; 255 [74%] male participants; mean Glasgow Coma Scale score, 8). Of these participants, 819 (84.8%) were available for primary outcome analysis at 6-month follow-up. The primary outcome occurred in 65% of patients in the tranexamic acid groups vs 62% in the placebo group (difference, 3.5%; [90% 1-sided confidence limit for benefit, -0.9%]; P = .16; [97.5% 1-sided confidence limit for harm, 10.2%]; P = .84). There was no statistically significant difference in 28-day mortality between the tranexamic acid groups vs the placebo group (14% vs 17%; difference, -2.9% [95% CI, -7.9% to 2.1%]; P = .26), 6-month Disability Rating Scale score (6.8 vs 7.6; difference, -0.9 [95% CI, -2.5 to 0.7]; P = .29), or progression of intracranial hemorrhage (16% vs 20%; difference, -5.4% [95% CI, -12.8% to 2.1%]; P = .16).

CONCLUSIONS AND RELEVANCE

Among patients with moderate to severe TBI, out-of-hospital tranexamic acid administration within 2 hours of injury compared with placebo did not significantly improve 6-month neurologic outcome as measured by the Glasgow Outcome Scale-Extended.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01990768.

Abstract 102: Cardiac Sodium/Glucose Cotransporter 1, a Novel Cardiac Glucose Transporter, Is Cardioprotective in Ischemia-Reperfusion Injury

Background: The expression of cardiac sodium/glucose cotransporter 1 (SGLT1) is up-regulated in ischemic heart disease. However, the regulation and the biological role of SGLT1 activity in cardiomyocytes are unclear.

Hypothesis: We hypothesize that SGLT1 inhibition during ischemia-reperfusion (IR) will lead to worsening cardiac function and recovery. In addition we hypothesize that SGLT1 expression is upregulated by increased AMPK activity in ischemia.

Methods: Transgenic mice with cardiac-specific RNAi knockdown of SGLT1 (TG SGLT1-KD ) were subjected to ex vivo IR (n > 3/group) using a Langendorff hanging heart preparation with 15 min of no-flow ischemia and 20 min of reperfusion while undergoing hemodynamic monitoring. FVB strain wild-type 8-12 week-old male mice (n > 3/group) were administered either the SGLT1 inhibitor phlorizin (400 mg/kg IP) or vehicle and subjected to in vivo ischemia for 30 min by ligation of the left anterior descending (LAD) coronary artery. Hearts were harvested 48 hours later. In vitro studies were conducted in HL-1 cardiomyocytes subjected to 1 h of simulated ischemia with 1 mM NaCN. HL-1 cells were also treated with 1 mM AICAR, an AMPK activator, for 16 hours and SGLT1 expression was measured.

Results: In ex vivo IR studies, there was an impairment in the early recovery of double product in the TG SGLT1-KD mice compared to control mice (37% vs 92% at 1 min into reperfusion, P < 0.05). In in vivo IR studies, phlorizin led to a marked increase in oxidative stress documented by cardiac malondialdehyde (MDA) (control 1.00±0.00; IR 1.55±0.35; IR + phlorizin 16.15±0.40, P <0.001),an increase in apoptosis documented by TUNEL staining, and hemodynamic impairment: +dP/dt (mmHg/sec), control 11445±504, IR 9811±2613, IR + phlorizin 5139±481, P <0.05; -dP/dt (mmHg/sec), control -10625±589, IR -6770±1142, IR + phlorizin -4153±474, P <0.05. In HL-1 cardiomyocytes, there was a 6.7-fold increase in SGLT1 expression after simulated ischemia, and a 2.0-fold increase after AICAR exposure.

Conclusion: SGLT1 expression increases when cardiomyocytes are subjected to ischemia, an effect that may be mediated by AMPK. Inhibition of SGLT1 leads to impaired myocardial recovery from ischemia.

Restoration of glucose metabolism in leptin-resistant mouse hearts after acute myocardial infarction through the activation of survival kinase pathways

In the normal heart, leptin modulates cardiac metabolism. It is unknown, however, what effect leptin has on cardiac metabolism and outcomes in acute myocardial infarction (MI). This study was performed to test the hypothesis that leptin signaling increases glucose metabolism and attenuates injury in the acutely infarcted heart. Mice with (ObR(+/+)) and without (ObR(-/-)) cardiomyocyte specific expression of leptin receptor (ObR) were randomly assigned to experimental MI or sham procedure, and studied 3 days later. ObR(+/+) and ObR(-/-) sham mice were not significantly different in any measured outcome. However, after MI, ObR(-/-) mice had greater cardiac dysfunction, left ventricular dilation, and levels of oxidative stress. These worse indices of cardiac injury in ObR(-/-) mice were associated with attenuated signal transducer and activator of transcription (STAT) 3, phosphatidylinositol-3-kinase (PI3K), and Akt signaling, decreased malonyl CoA content, and reduced mitochondrial pyruvate dehydrogenase and electron transport Complex I, II and IV activities. Furthermore, ObR(-/-) mice maintained high rates of cardiac fatty acid oxidation after MI, whereas ObR(+/+) mice demonstrated a switch away from fatty acid oxidation to glucose metabolism. Restoration of cardiac STAT3, PI3K and Akt activity and mitochondrial function in ObR(-/-) mice post-MI was accomplished by ciliary neurotrophic factor (CNTF), an established STAT3 activator, administered immediately after MI. Moreover, CNTF therapy resulted in mitigation of cardiac structural and functional injury, attenuated levels of oxidative stress, and rescued glucose metabolism in the infarcted ObR(-/-) heart. These data demonstrate that impaired cardiac leptin signaling results in metabolic inflexibility for glucose utilization in the face of cardiac stress, and greater morbidity after MI. Further, these studies show that cardiac glucose metabolism can be restored in leptin-resistant hearts by CNTF-mediated activation of survival kinases, resulting in multiple improved structural and functional outcomes post-MI.