Regression of cardiac amyloid deposits with novel therapeutics: reaching new frontiers in cardiac ATTR amyloidosis

Background

Cardiac involvement is the main driver of outcome in ATTR amyloidosis. Advances in therapeutics hold potential in transforming the course of the disease but the impact on cardiac amyloid load is unknown. The aim of this study was to evaluate the impact of patisiran, a new double stranded RNA based gene silencing therapy and a stabilizer, diflunisal, on cardiac amyloid load as measured by CMR and T1 mapping, in patients with ATTR amyloidosis.

Methods and results

Thirty-two patients with hereditary cardiac amyloidosis were studied. Sixteen patients received treatment with patisiran, and sixteen control subjects did not receive any disease modifying treatment. Patients were assessed with echocardiogram, CMR, NT-proBNP and six-minute walk time measurements at baseline and at 1 year (Mean interval 11.45±3.08 months in treatment group, mean interval 12.82±5.06 months in the control group). CMR analysis comprised LV volumes, T1 mapping to measure the extracellular volume (ECV) occupied by amyloid, T2 mapping and late gadolinium enhancement imaging. At 1-year follow-up, there was a substantial reduction in cardiac amyloid burden, in keeping with cardiac amyloid regression in 45% of patients on treatment. Overall the treatment group showed a reduction in ECV at 1 year follow up compared to an increase in ECV at 1 year in the control group (−1.37%, 95% CI: −3.43 to 0.68% versus 5.02%, 95% CI: 2.86% to 7.18% respectively, p<0.001). The treatment group also showed an improvement in change in 6MWT at 1 year follow up compared to 6MWT at 1 year in the control group (−8.12 meters, 95% CI: −50.8 to 34.6 meters in the treatment group versus −132.27 meters, 95% CI: −216 to −48.6 meters in the control group, p=0.002). The treatment group showed a reduction in BNP at 1 year follow up compared to an increase in the control group (−567.87, 95% CI: −1288.90 to 153.15 in the treatment group versus 2004, 95% CI: 12.82 to 3995.45 in the control group, p<0.001). There was no significant difference from baseline and 1-year data between the control and treatment groups for the difference in echocardiographic parameters, native T1, T2. There was a significant reduction in the percentage of injected dose by 99Tc-DPD scintigraphy in treated patients at 1 year compared to baseline.

Conclusions

These findings provide the first compelling evidence of substantial cardiac amyloid regression in ATTR amyloidosis, as well as the potential for CMR to be used to track response in treated patients with ATTR cardiac amyloidosis. Combination therapy with transthyretin knock down and stabilizing agents may well be synergistic given enhanced stoichiometry of stabilizers in the face of much reduced plasma transthyretin concentration.

Funding Acknowledgement

Type of funding source: None

A Comparison of Locking Plates and Intramedullary Pinning for Fixation of Metacarpal Shaft Fractures

BACKGROUND

Metacarpal shaft fractures that necessitate surgery are frequently fixated with either intramedullary pins or plates and screws. This study compared outcome measurements of these two techniques.

METHODS

Patients operated on for closed shaft fractures of metacarpals 2-5 were examined at least 1 year after injury. All fractures were fixated by pinning between years 2013 and 2015 and by locking plates and screws between 2016 and 2017. Evaluation included range of motion measurements for all fingers compared with the contralateral hand; comparison of grip strength; finger alignment and rotation; Disabilities of the Arm, Shoulder and Hand (DASH) score; and radiographic measurements of fracture reduction and healing.

RESULTS

Thirty patients with 39 fractured metacarpals treated by pinning were compared with 29 patients with 35 fractured metacarpals treated by locking plate and screws. Both groups had similar characteristics and preoperative fracture patterns on radiograph. Patients in the plate group were found to have significantly improved outcomes in total range of motion of the operated digits (loss of 4° extension, 10° flexion, and 14° total vs 10° extension, 19° flexion, and 29° total), grip strength (93% vs 83% of contralateral hand), rotational deformity (5 digits, 1° vs 15 digits, 6°), and DASH score (10.5 vs 15.6). Radiographic bone healing time (59 vs 50 days) and operative time (58 vs 41 minutes) were both significantly longer in fractures fixated by plates.

CONCLUSIONS

Fixation with locking plates allows earlier mobilization without need for splinting. Our study supports the use of this method over intramedullary pinning for metacarpal shaft fractures.

Hairline fractures following volar plating of the distal radius: a recently recognized hardware-related complication

OBJECTIVES

Intraoperative hairline longitudinal fractures were recently reported in association with distal radius volar plating. Our aim was to further analyze this newly described complication.

METHODS

A retrospective radiographic and chart review was performed on 225 patients who underwent distal radius plating between June 2013 and June 2015. The Acu-Loc/Acu-Loc2© plating system (Acumed, Hillsboro, OR, USA) was used in 208 cases, and the VariAx© plating system (Stryker, Kalamazoo, MI, USA) was used in 17 cases. Three independent reviewers performed a blind evaluation of all relevant radiographs for the occurrence of longitudinal fractures around the plate, and validity was considered only when there was agreement among all three of them.

RESULTS

Hairline longitudinal fractures were identified in 57 cases (25%), 55 with the Acu-Loc/Acu-Loc2© system and 2 with the VariAx© system. All fractures occurred with volar plating. Fracture occurrence was associated with age over 59 years, female gender, extra-articular fractures, and the use of Hexalobe screws (Acu-Loc/Acu-Loc2© system).

CONCLUSIONS

We believe that the source of fracture occurrence lies within the screw design and that better screw design and possibly tapping in patients at risk may reduce the occurrence of intraoperative hairline longitudinal fractures. Further clinical and biomechanical research is needed to better understand this newly reported complication.

Transthyretin V122I amyloidosis with clinical and histological evidence of amyloid neuropathy and myopathy

Hereditary transthyretin amyloidosis (ATTR) is a genetically and clinically heterogeneous disease manifesting with predominant peripheral and autonomic neuropathy; cardiomyopathy, or both. ATTR V122I is the most common variant associated with non-neuropathic familial amyloid cardiomyopathy. We present an unusual case of V122I amyloidosis with features of amyloid neuropathy and myopathy, supported by histological confirmation in both sites and diffuse tracer uptake on (99m)Tc-3,3-Diphosphono-1,2-Propanodicarboxylic acid (DPD) scintigraphy throughout skeletal and cardiac muscle. A 64 year old Jamaican man presented with cardiac failure. Cardiac MR revealed infiltrative cardiomyopathy; abdominal fat aspirate confirmed the presence of amyloid, and he was homozygous for the V122I variant of transthyretin. He also described general weakness and EMG demonstrated myopathic features. Sural nerve and vastus lateralis biopsy showed TTR amyloid. The patient is being treated with diflunisal, an oral TTR stabilising agent. Symptomatic myopathy and neuropathy with confirmation of tissue amyloid deposition has not previously been described. Extracardiac amyloidosis has implications for diagnosis and treatment.

Asthma experience in an occupational and environmental medicine clinic. Low-dose reactive airways dysfunction syndrome

The etiology of adult-onset asthma is incompletely understood. High-intensity exposure to irritants is one accepted risk factor and such cases are termed Reactive Airways Dysfunction Syndrome. The contribution to asthma of less intense and less acute exposure to irritants remains to be clarified. We report on 10 cases of nonsensitization adult-onset asthma in settings of exposure to noticeable but distinctly "tolerable" levels of inhalation irritants. This series of 10 cases represent 31% of verified asthma cases seen in our environmental and occupational medicine referral clinic over a 5-year period. We believe further exploration of this phenomenon of low dose Reactive Airways Dysfunction Syndrome is warranted.