Objective To determine the rate of late complications following first implantation or elective unit replacement of a permanent pacemaker system.

Design Analysis of pacemaker data and complications prospectively acquired on a computerised database. Complications were studied over an 11 year period from January 1984 to December 1994.

Setting Tertiary referral cardiothoracic centre.

Patients Records of 2621 patients were analysed retrospectively.

Main outcome measures Complications requiring repeat procedures occurring more than six weeks after pacemaker implantation or elective unit replacement.

Results The overall rate of late complications was significantly lower after first implantation of a permanent pacemaker (34 cases, complication rate 1.4%, 95% confidence interval 0.9% to 1.9%) than after elective unit replacement (16 cases, complication rate 6.5% (3.3% to 9.7%). There were 20 cases of erosion, 18 infections, five electrode problems, and seven miscellaneous problems. Complications were more common with inexperienced operators (18.9% (6.0% to 31.8%)) than with experienced operators (0.9% (0.3% to 1.5%)).

Conclusions The incidence of late complications following pacemaker implantation is low and compares favourably with early complication rates. The majority are caused by erosion and infection. Patients who have undergone elective unit replacement are at particular risk.