Left ventricular performance in chronic mitral regurgitation: temporal response to valve repair and prognostic value of early postoperative echocardiographic parameters.

: Misplacement of a permanent pacemaker lead has been described in several locations but rarely in the left ventricle. Less commonly, as described in our report, malposition may occur when the lead perforates the interatrial septum and extends across the left atrium and through the mitral valve into the left ventricle. The actual incidence of this pacemaker complication is unknown. Consequences may include perforation and systemic or cerebral thromboembolic events. We report the case of a patient with unintentionally misplaced left heart pacemaker lead admitted for neurological symptoms consistent with embolic stroke. The patient was on aspirin when symptoms occurred. The lead misplacement was not recognized at the time of implantation. Pacing threshold was normal. A 12-lead electrocardiogram showed right bundle branch block configuration paced complexes. By two-dimensional and transesophageal echocardiography, the pacemaker lead was carefully evaluated. The pacemaker lead crossed the interatrial septum, the left atrium, the mitral valve to be implanted in the left ventricular endocardium. To avoid the risk of future embolization, it was felt that the lead should be removed and right ventricular pacing established, once anticoagulation treatment was initiated. Successful percutaneous lead replacement was accomplished without sequelae. Measures to avoid lead misplacement are suggested.