In conclusion, we propose the following approach to prevent and manage lead malposition in the left ventricle: A 12-lead electrocardiogram in the paced mode and an anterior and lateral chest view should be thoroughly inspected shortly after pacemaker implantation. A definitive diagnosis of malposition can be established with these tests. Development of any neurologic symptoms should be attributed to the malpositioned lead until proved otherwise. In such patients, serious consideration should be given to transcatheter or surgical lead extraction after a period of anticoagulation. If this is not possible, chronic anticoagulation with warfarin must be initiated, achieving an international normalized ratio of > or = 2.5. Antiplatelet therapy alone may not confer adequate protection against future cerebral events. Furthermore, most patients with neurologic manifestations do not have echocardiographic evidence of thrombus on the lead. Conversely, presence of thrombus is highly associated with neurologic symptoms. Any intraarterial lead must be removed due to inevitable complications. Patients who have remained completely asymptomatic for > or = 3 years may be followed carefully with no therapy. For asymptomatic patients diagnosed before this time period, we recommend empiric therapy with antiplatelet agents or low-dose warfarin (international normalized ratio 1.5-2) with careful observation for symptoms.