BOSTON — Patients who received implanted cardiac devices in routine practice in recent years had much better survival than did those who received the same devices in the pivotal trials of the early 2000s, based on data from nearly 86,000 patients.
This first analysis of a huge amount of data from patients with implantable cardioverter defibrillators (ICDs) or cardiac resynchronization therapy-defibrillators (CRT-Ds) collected in a device-monitoring network also showed that a substantial number of “inappropriate” shocks that patients received might actually be clinically appropriate, Dr. Leslie A. Saxon said at the Heart Rhythm Society's annual meeting.
“We traditionally program [these devices] to just shock patients for malignant ventricular arrhythmias. But about 20% of the inappropriate shocks were for atrial fibrillation with more than 200 beats/min. The clinical appropriateness of shocks for heart rates of more than 200 bpm is an interesting question,” said Dr. Saxon, chief of cardiovascular medicine at the University of Southern California, Los Angeles.
The ALTITUDE clinical science program sponsored by Boston Scientific collected data through the company's LATITUDE patient management system on 47,032 patients who received an ICD and 38,967 who received a CRT-D during 2006-2009. Dr. Saxon, chair of the ALTITUDE physician panel, said she has financial ties with Boston Scientific and several other companies that market cardiac devices.
As of February 2009, the average age of ICD patients in the database was 64 years, with an average implant duration of 40 months. The CRT-D patients were age 69 on average, with implant ages of 32 months.
In the first year of follow-up, the survival rate was 99% in the ICD patients and 96% in those with a CRT-D. These rates compare favorably with the 91%-94% survival rates with ICDs from the two major randomized, clinical trials, the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), and with the 89% survival rate with CRT-D in the major trial for that device, Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION).
The results also confirmed that patients who receive shocks have worse survival than patients who do not (see chart). During follow-up, 19,522 patients received an ICD or CRT-D shock. An adjudication committee reviewed a representative sample of 1,272 shocks. Shocks for an “appropriate” reason—a ventricular arrhythmia—occurred 57% of the time; “inappropriate” shocks made up the remaining 43%. Within that group, 83% were for atrial fib or flutter, 12% were for “noise,” and 5% occurred after an appropriate arrhythmia had stopped, Dr. Saxon said.
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