Disease-Modifying Treatments for Transthyretin Amyloidosis.

ABSTRACT: The transthyretin (TTR) amyloidoses result from misfolding of the protein leading to fibril formation and aggregation as amyloid deposits in predominantly the cardiovascular and nervous systems. Cardiac involvement can manifest as heart failure, arrhythmias, and valvular disease. Neurologic involvement can cause sensorimotor polyneuropathies, mononeuropathies, and dysautonomia. Previously, treatment has focused on management of these symptoms and disease sequelae, with a high rate of mortality due to the absence of disease-modifying therapies. In this article, we review novel treatments focusing on 3 mechanistic pathways: (1) silencing of the TTR gene to suppress production, (2) stabilizing of TTR tetramers to prevent misfolding, or (3) disrupting of existing TTR amyloid fibrils to promote reabsorption.

Usefulness of Canakinumab to Improve Exercise Capacity in Patients With Long-Term Systolic Heart Failure and Elevated C-Reactive Protein.

Interleukin-1ß (IL-1ß) is a cytokine involved in atherothrombosis and is known to depress cardiac function. We hypothesized that blocking IL-1ß in patients with symptomatic systolic heart failure (HF) would improve their cardiorespiratory fitness. The purpose of the study was to measure changes in peak oxygen consumption (VO2) in 30 patients with prior myocardial infarction, high-sensitivity C-reactive protein ≥ 2 mg/l and HF with left ventricular ejection fraction (LVEF) < 50% enrolled in the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) in an independent single center substudy. We measured peak VO2 before and after 3 and 12 months of treatment with Canakinumab every 3 months (50, 150, or 300mg subcutaneously) or placebo, and measured LVEF before and after 12 months. In December 2013, the CANTOS study announced early termination of enrollment, halting enrollment for this substudy after only 15 patients, of which 3 were assigned to placebo and 12 to Canakinumab (50mg [1; 7%], 150mg [5; 33%], 300mg [6; 40%]). Patients treated with Canakinumab had a significant improvement in peak VO2, from 19.2 to 22.8 ml/kg/min at 3 months (p = 0.023 within-group changes, p = 0.026 for time_x_group interaction versus placebo [primary end point]), and an improvement in LVEF 38% (33-43) to 44% (38-52) at 12 months (p = 0.012 for within-group changes). No significant changes were seen in the placebo group. In conclusion, the findings of this small prespecified secondary analysis of the CANTOS trial support the positive results of the overall study, and confirm IL-1 as a potential therapeutic target in HF. https://clinicaltrials.gov/ct2/show/NCT01900600.

Usefulness of C-Reactive Protein Plasma Levels to Predict Exercise Intolerance in Patients With Chronic Systolic Heart Failure.

Patients with heart failure (HF) have evidence of chronic systemic inflammation. Whether inflammation contributes to the exercise intolerance in patients with HF is, however, not well established. We hypothesized that the levels of C-reactive protein (CRP), an established inflammatory biomarker, predict impaired cardiopulmonary exercise performance, in patients with chronic systolic HF. We measured CRP using high-sensitivity particle-enhanced immunonephelometry in 16 patients with ischemic heart disease (previous myocardial infarction) and chronic systolic HF, defined as a left ventricular ejection fraction ≤ 50% and New York Heart Association class II-III symptoms. All subjects with CRP >2 mg/L, reflecting systemic inflammation, underwent cardiopulmonary exercise testing using a symptom-limited ramp protocol. CRP levels predicted shorter exercise times (R = -0.65, p = 0.006), lower oxygen consumption (VO2) at the anaerobic threshold (R = -0.66, p = 0.005), and lower peak VO2 (R = -0.70, p = 0.002), reflecting worse cardiovascular performance. CRP levels also significantly correlated with an elevated ventilation/carbon dioxide production slope (R = +0.64, p = 0.008), a reduced oxygen uptake efficiency slope (R = -0.55, p = 0.026), and reduced end-tidal CO2 level at rest and with exercise (R = -0.759, p = 0.001 and R = -0.739, p = 0.001, respectively), reflecting impaired gas exchange. In conclusion, the intensity of systemic inflammation, measured as CRP plasma levels, is associated with cardiopulmonary exercise performance, in patients with ischemic heart disease and chronic systolic HF. These data provide the rationale for targeted anti-inflammatory treatments in HF.