Evidence of low-grade intravascular coagulation in patients with transvenous pacemakers

Serum fibrin and fibrinogen degradation products (FDP) were measured in 4 groups of patients. In Group A (30 patients) FDP levels were measured before and 48-60 hours after pacemaker and transvenous electrode placement. They remained negative (less than 10 micrograms/ml) in 14, rose to greater than 10 micrograms/ml less than 40 micrograms/ml in 12, and greater than 40 micrograms/ml in 4. In 12 Group B patients undergoing the same procedure, FDP levels remained negative in 8, and rose in 4 after 24 hours and after 7 days. In 12 Group C patients studied at initial electrode and battery implantation and 3-6 months later, there were the same results in short- and long-term FDP measurements (8 negative and 4 elevated). Finally, in 14 patients with negative FDP levels who underwent battery replacement only, 3.1 to 5.2 years after their initial operation (Group D), no increase of FDP titer was seen postoperatively. Our results suggest that elevated FDP levels suggest subclinical intravenous or intracardiac thrombosis in patients with transvenous pacemakers.