I first wrote
about pheo and heart 4 years ago (April 2009). At that time, my instinct was
that heart damage is a key issue for pheo. Over the years, after seeing more
patients with heart complications caused by pheo and discussing with colleagues
about the issue, I increasingly appreciate the intricacies of pheo-induced
cardiomyopathy.
Pheo-induced
cardiomyopathy is not a new finding. The first two cases of pheo known to medicine
were both about pheo-induced cardiovascular collapse in modern terms. The
correlation of pheo and cardiomyopathy was clearly and convincingly reported in
the 1960s. Hundreds of case reports of pheo-induced cardiomyopathy have been
published in the last 50 years. The problem is that pheo is very rare and
pheo-induced cardiomyopathy is even rarer. Many cardiologists and
endocrinologists simply are not aware of the concept of pheo-induced
cardiomyopathy. Part of the reason why pheo-induced cardiomyopathy is not well
known is that there are few, if any, systemic studies on pheo-induced
cardiomyopathy.
In the last year,
two very similar systemic studies were published on pheo-induced
cardiomyopathy. Both studies were retrospective review of experience of a large
single medical center (in Prague and Los Angeles, respectively). In both
studies, the authors focused on patients without known history of
pheochromocytoma but presenting with cardiovascular complications such as
arrhythmia, heart attack, heart failure, or stroke. Their results were
strikingly similar as well. The Prague study included 145 patients, 28 of them
(19%) presented with cardiovascular complications. The Los Angeles study was
about half the size with 76 patients, but still 9 of them (12%) presented with
heart complications. Because both medical centers are large tertiary referral
centers and tend to see sicker patients, the incidence of cardiovascular
complications may be overestimated but the 12-19% incidence is at least true in
large hospitals. Both studies showed that there are no good predictors on which
patients will get cardiovascular complications. Specifically, most patients
with cardiovascular complications do not have hypertension. There may be a
higher risk for cardiovascular complications if the pheo is biochemically very active
and large. I have mentioned in a previous post that pheos smaller than 3 cm do
not cause cardiovascular complications. Both studies showed that once correctly
diagnosed and managed, the pheo-induced cardiomyopathy is reversible. The moral
of the studies is that if a patient presents with cardiovascular complications,
pheo is a possibility, even if the patient has no history of hypertension. It
is also reassuring that the cardiomyopathy is reversible after pheo removal.
Dr. Pheo
