Worsening of mitral regurgitation secondary to ventricular pacing

A 68-year-old woman was admitted to hospital for possible mitral valve surgery for severe mitral regurgitation (MR). Six months before admission, a DDD pacemaker was implanted for symptomatic bradycardia. She developed atrial fibrillation and the pacer was changed to a VVI mode. At cardiac catheterization, the pulmonary artery and wedge pressures were elevated; coronary angiography showed non-obstructive coronary artery disease. 2-D echocardiography confirmed preserved left ventricular function, severe MR and moderate tricuspid regurgitation. The change in pacing had a dramatic effect on MR severity; ventricular pacing was associated with a MR jet that occupied a larger area of the left atrium than with the unpaced rhythm, the continuous-wave mitral regurgitant Doppler profile was 'dagger'-shaped, and the signal intensity stronger compared with the unpaced rhythm. These findings are consistent with severe MR. The pacer was reprogrammed to reduce the pacing rate from 70 to 45 beats/min, allowing an unpaced rhythm for the most part. The patient improved and was discharged two days later. Six months later she was asymptomatic; repeat echocardiography confirmed mild to moderate MR.