The formation of thrombi on a permanent pacemaker lead has been reported as a rare complication following the implantation of a permanent pacemaker. However, there is little information about the complications related to modern cardiac pacing. The purpose of this study was to evaluate the factors associated with the formation of a lead thrombosis following the implantation of a permanent pacemaker (P-PM).

We retrospectively reviewed the medical records of 14 patients (M:F= 6:8, mean age=46±11) with P-PM lead thrombus that were detected with a transthoracic echocardiography. The clinical features, type of pacemaker and echocardiographic findings of these patients were analyzed.

All thromb us formations had developed in the right atrium (RA), and/or superior vena cava (SVC)(100%, n=14), were mainly in the proximal portion of the RA (71.4%, n=10) and on the ventricular lead (64.3%, n=9). 12 of 14 patients (85.7%), The lead thromboses were atrial fibrillation, with tachy-brady syndrome or sinus pause. Three of the patients had a total SVC obstruction and 1 a thrombus with aspergillosis. The lead thrombus in one patient was completely resolved after thrombolytic treatment. There were no significant differences in the incidences of lead thrombosis in relation to the number of implanted leads, insulation type, echocardiographic parameters.

Lead thromboses might not be a rare complication following the implantation of a P-PM, and frequently occur in the right atrium of patients with atrial pathology. The necessity for thrombolytic therapy in patients with a lead thrombus should be further investigated.