Treating cardiological complications caused by amyloidosis
Les traitements de l'amyloses
Treatment for amyloid cardiopathies essentially consists of diuretic therapy and restricting the amount of sodium in the diet relative to congestion levels. Beta-blockers and bradycardia treatments are not recommended. Raising the heart-rate is the only way to maintain the heart’s output (cardiac output = heart rate x stroke volume), as the myocardial walls are stiff due to myocardial infiltration, preventing any increase in ejection volume (stroke volume = end-diastolic volume – end-systolic volume). Medications which have negative dromotropic effects are not advised as they can aggravate conduction disorders.
Doctors must be wary of hypotensive treatments for patients with amyloidosis as they can trigger dysautonomia and lead to falls.
Arrhythmias are common and it is often necessary to use antiarrhythmic drugs. Amiodarone is the usual medication of choice to maintain sinus rhythm in paroxysmal atrial fibrillation. It is normally not advised to use digoxin to treat arrhythmias because of its potential toxic effects. Screening for conduction disorders must also be carried out, first with an ECG and then using a Holter monitor. An endocardial examination investigating prolonged Infra-Hisian conduction time (measurement of HV) might also be necessary. Due to the high risk that patients will develop a conduction disorder, pacemakers are often implanted as soon as anomalies start to show.
The risk of embolism is high, particularly when the atria have been infiltrated (detectable by MRI) because they lose their contractile activity, despite the fact that their electrical activity is normal, namely in sinus rhythm.
Treatment for AL amyloidosis has come a long way and new chemotherapies mean that patient prognostic has considerably improved. It is common to observe the infiltration regressing and an improvement in symptoms.
Treatment for transthyretin amyloidosis is also developing fast. For the past 10 years, liver transplants have been the usual treatment for hereditary amyloidosis and in cases where the patient also has cardiac damage, this is combined with a heart transplant. Of course, this is only possible for young patients without significant neurological damage. New medical treatments have emerged and must be tested to see how well they treat cardiac damage. A transthyretin tetramer stabiliser (tafamidis) has obtained its European market authorisation for hereditary TTR amyloidosis with neuropathy and is now in preparation for cardiac damage. Another medication which blocks transthyretin production (antisense oligonucleotide) is also in the clinical trial phases. A component of green tea (epigallocatechin-3-gallate, EGCG) has also shown its value in reducing the left ventricular mass measured in echocardiographs and MRIs in a small, non-randomised study.
Cardiac transplantation is possible in patients less than 65 years old if they have had a full evaluation and a specialised multidisciplinary team is available.
Prognosis for transthyretin amyloidosis is better than that of AL amyloidosis but cardiac amyloidosis is still a terminal illness. Early diagnosis is essential to prevent complications and put in place the right treatment for the type of amyloidosis.
Cardiac amyloidosis requires expert care for both diagnosis and treatment. Cardiologists must keep this in mind with any form of hypertrophic cardiomyopathy. New imaging techniques have made detecting this much easier. With time, developing new treatments will also improve prognosis.
Role of (99m)Tc-DPD scintigraphy in diagnosis and prognosis of hereditary transthyretin-related cardiac amyloidosis. Rapezzi C, Quarta CC, Guidalotti PL, Pettinato C, Fanti S, Leone O, Ferlini A, Longhi S, Lorenzini M, Reggiani LB, Gagliardi C, Gallo P, Villani C, Salvi F. JACC Cardiovasc Imaging. 2011 Jun;4(6):659-70.