Context Thrombotic thrombocytopenic purpura (TTP) is a rare
and often fatal disorder characterized by thrombocytopenia,
microangiopathic hemolytic anemia, mental status changes, and renal
dysfunction. Ticlopidine hydrochloride is 1 of several drugs that have
been associated with this disorder and is currently used routinely in
the approximately 500,000 patients per year in the United States
who undergo a percutaneous coronary intervention involving a stent.
Objectives To determine the incidence and describe the clinical
course of TTP due to ticlopidine therapy following stenting.
Design Retrospective analysis of cohort of all patients
undergoing coronary stenting at the Evaluation of Platelet IIb/IIIa
Inhibitor for Stenting (EPISTENT) study sites.
Setting Sixty-three centers throughout the United States and
Patients A total of 43,322 patients who underwent a
percutaneous coronary intervention and received a coronary stent during
a 1-year period from 1996 to 1997.
Main Outcome Measures Cases of TTP following stenting during the
1-year period to determine the incidence of TTP due to ticlopidine
therapy following coronary stenting. Additional cases were collected
from these and other centers across North America to further describe
the clinical presentation and course of TTP due to ticlopidine therapy
Results Nine cases of TTP following stenting were recognized at
the 63 centers during the specified period, giving an incidence of 1
case per 4814 patients treated (0.02%; 95% confidence interval, 1
case per 2533 to 1 case per 10,541 patients treated). Ten
additional cases of TTP related to ticlopidine therapy following
stenting were identified from other centers, were identified from the
primary centers outside the predefined period, or involved a
noncoronary stent. Four patients (21%) received ticlopidine for 2
weeks or fewer, 14 patients (74%) for 2 to 4 weeks, and 1 patient
(5%) for 8 weeks. The mean time of ticlopidine treatment prior to TTP
diagnosis was 22 days (range, 5-60 days). The overall mortality rate
was 21% (4/19), with all 4 deaths occurring in patients not treated
with plasmapheresis, whereas there were no deaths among the 13 patients
who received plasmapheresis.
Conclusion The findings of a TTP incidence of 0.02% in our
cohort of ticlopidine-treated patients following coronary stenting
suggests that TTP occurs much more commonly in this population than the
estimated incidence of 0.0004% in the general population. The
mortality rate for this rare complication exceeds 20%. Limiting
ticlopidine therapy to 2 weeks after stenting does not prevent the
development of TTP. Rapid diagnosis and treatment that includes
plasmapheresis are critical for improved survival.