#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.
Background:
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.
Methodology:
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.
Results:
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
Conclusions:
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.
