"We were surprised at how frequently these thrombi develop," Dr. Gregory E. Supple from University of Pennsylvania in Philadelphia told Reuters Health by email.

"Given the potential for adverse clinical consequences from thromboembolism to the pulmonary vasculature, we are alarmed at how commonly we identified mobile thrombi on patients' device leads," he said.

Thrombi on intracardiac leads are sometimes missed on transthoracic echocardiography (TTE), Dr. Supple and his colleagues said in the August 16 online issue of Circulation -- but the ablation procedures in their report were guided by intracardiac echocardiography (ICE).

All of the 86 study participants had pacemakers or implantable cardioverter-defibrillators.

Twenty-six patients (30%) had 30 lead thrombi identified with intracardiac echocardiography (ICE). None had shown up on routine TTE, and routine transesophageal echocardiograms in five patients also missed them.

Mobile lead thrombi were tied to significantly higher pulmonary artery systolic pressures but not with any other clinical characteristics.

There were, however, nonsignificant associations between the presence of lead thrombus and an increased number of endocardial leads and increased lead age and between warfarin use and the absence of lead thrombus.

"Thrombi are likely forming on cardiovascular implantable electronic device leads more frequently than is recognized," Dr. Supple said. "The clinical relevance of lead thrombi is still not well understood, but the alarming frequency highlights the need for further investigation."

"Unfortunately, we have not yet identified any clinical factor that we would have suspected would help reduce the formation of lead thrombi," he added.

"However, we have seen that in some cases lead thrombi can develop very rapidly, and therefore it may be that even transient periods of subtherapeutic anticoagulation allow thrombi to form. If this is the case, perhaps more diligent attention to persistent anticoagulation would be of benefit."

By Will Boggs, MD

Source: http://bit.ly/o6vPmW

Circulation 2011.

Last Updated: 2011-08-22 11:54:11 -0400 (Reuters Health)

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