#amyloidosisJC returns at 9 pm EST on Monday February 29th 2016 with a discussion focusing on the role of implanted cardiac defibrillators (ICDs) as a means of improving survival of patients with cardiac amyloidosis. Thank you to Dr. Naresh Bumma (a Karmanos Cancer Institute hematology-oncology fellow, @NB191186 on Twitter) for his help preparing a summary of the following article from the Mayo Clinic:
Published in the Journal of Cardiovascular Electrophysiology, 2013: 24(7), 793-798.
Cardiac involvement with systemic amyloidosis by characterized by infiltration and/or deposition of amyloid chains in the myocardium leading to wall thickening and valvular damage. The presence of cardiac involvement is usually associated with high mortality, in part due to a high risk of fatal arrhythmias. However, the benefit of implantable cardiac defibrillator (ICD) placement in this population remains controversial due to the lack of compelling evidence that it reduces mortality.
Retrospective chart review of all cardiac amyloidosis (CA) patients between 2000 and 2009 seen at a single institution (the Mayo Clinic). All cases of systemic amyloidosis were diagnosed by tissue biopsy and cardiac involvement was established by right ventricular biopsy or echocardiographic findings (left ventricular wall thickness >12 mm in the absence of other etiologies). Patients who underwent ICD implants were identified and characterized. Patients were staged according to the 2004 Mayo staging criteria using troponin T and NTproBNP measurements.
892 patients were found to have typical features of CA and out of these 53 underwent ICD placement. Of these 53 patients, 33 had AL, 10 had wild-type ATTR, 9 had familial and 1 had AA amyloidosis.
Forty-one patients (77%) underwent ICD placement for primary prevention (18 with unexplained syncope, 9 with left ventricular ejection fraction ≤ 35%, 6 with non-sustained VT, and 8 who were considered high risk for other reasons by their treating physican(s)). Twelve patients (23%) underwent ICD placement for secondary prevention due to sustained ventricular arrhythmia or previous sudden cardiac arrest.
During follow-up (23.25 ± 21.45 months from ICD implantation), 15 patients received at least one appropriate ICD shock, with 12 out of 15 of these occurring in AL patients.
AL amyloidosis subgroup (n=33):
Twelve (36%) underwent successful autologous SCT (including one who underwent orthotopic heart transplantation prior to ASCT) and 21 (64%) were treated with nonmyeloablative chemotherapy.
Median surival was 7.5 months (similar to their historical cohort where median surivival was 10 months, p=0.31)
Familial, AA and wild-type ATTR amyloidosis:
Numbers were insufficient to draw any statistical comparisons
Despite a high rate of appropriate ICD discharges, there has been no overall survival benefit seen in this cohort with ICD placement for CA compared to cotemporaneous patients without ICD placement. Possible explanations for these findings are that cardiac deaths due to pump failure (rather than arrhythmias) may account for the observed poor survival in CA patients, or that patient selection for ICD placement needs refinement.