Pulmonary Vein Stenosis After Atrial Fibrillation Ablation
abstract & commentary
Synopsis: Pulmonary vein stenosis is a potentially life-threatening complication of atrial fibrillation ablation using current radiofrequency catheter ablation techniques.
Source: Robbins IM, et al. Circulation 1998;98: 1769-1775.
Previously in Clinical Cardiology Alert, we reported the promising possibility of preventing some recurrent atrial fibrillation by pulmonary vein ablations. Robbins and colleagues from the University of Alabama report a serious complication related to radiofrequency catheter ablation in the left atrium in proximity to the pulmonary veins for the treatment of atrial fibrillation. Robbins et al were involved in a multicenter, prospective trial examining the effects of catheter ablation on atrial fibrillation. Two patients from Robbins’ center developed late pulmonary hypertension. The first patient was a 53-year-old man with chronic atrial fibrillation who had failed multiple antiarrhythmic drugs. Catheter ablation of atrial fibrillation was scheduled as an investigational procedure. Before the procedure, he had a two-dimensional echocardiogram that showed normal left ventricular function, a left atrial dimension of 38 mm, and an estimated pulmonary artery systolic pressure of only 39 mmHg. The ablation procedure involved applications of radiofrequency current in both right and left atria. In the left atrium, several ablation lines were made: 1) from the right upper pulmonary vein to the left upper pulmonary vein and then to the mitral annulus; 2) from just to the left of the posterior intra-atrial septum to the ostium of the right superior pulmonary vein; and 3) diagonally across the roof of the left atrium. Two ablation lesions were also placed in the right atrium. Total procedure duration was eight hours. Conversion to sinus rhythm occurred during the procedure. Two months after the initial ablation procedure, the patient developed an episode of atrial flutter and underwent a second right atrial ablation. The patient has not had recurrent atrial arrhythmias since that second procedure. Three months after the initial procedure, however, the patient noted the onset of progressive dyspnea on exertion and cough. An echocardiogram demonstrated an estimated pulmonary artery systolic pressure of 65 mmHg. The patient was treated with oral amlodipine and intravenous prostacycline with no improvement. His pulmonary hypertension progressed. Eventually, he underwent selective catheterization and venography of the pulmonary veins. All four of the pulmonary veins demonstrated localized stenoses within 10 mm of their ostia. Balloon dilation of the pulmonary veins was performed with an improvement in his symptoms. Partial correction of the pulmonary hypertension was documented, with a decrease in his pulmonary artery pressures from 98/36 to 54/24 mmHg.
The second patient had a similar course. She was a 36-year-old woman with a 19-year history of refractory paroxysmal atrial fibrillation. She also had both left and right atrial ablations during the initial procedure and a second right atrial ablation. Since the second ablation procedure, she has had no recurrent arrhythmias. However, after the procedure, she developed symptoms of cough and dyspnea. Over the succeeding 12 months, she developed progressive pulmonary hypertension. Measured pulmonary artery pressures were 90/50 mmHg. During a diagnostic catheterization, severe stenoses of three pulmonary veins were noted. The right lower pulmonary vein was occluded.
Among the other 16 patients enrolled in this multicenter trial, repeat Doppler echocardiography at one month, three months, and six months after ablation has not identified any other patients with increased pulmonary artery pressures.
Robbins et al conclude that pulmonary vein stenosis is a potentially life-threatening complication of atrial fibrillation ablation using current radiofrequency catheter ablation techniques. Robbins et al urge that future studies on the use of ablation for atrial fibrillation consider this potential complication and use strategies to protect the pulmonary veins.
Comment by John P. DiMarco, MD, PhD
Ablation of atrial fibrillation has remained an elusive goal. The surgical MAZE procedure pioneered the concept that the use of linear incisions in both left and right atria could control atrial fibrillation. The surgical MAZE procedure isolates the pulmonary vein with a circumferential incision. Catheter procedures have attempted to duplicate the electrophysiologic effects of this incision by placing linear ablation lines in proximity to the ostia of the pulmonary veins. In some patients, identification of a focal source for atrial fibrillation has led to radiofrequency applications within the pulmonary veins. This paper by Robbins et al raises a warning flag about widespread application of these techniques.
The pathology of radiofrequency ablation lesions in atrial and ventricular myocardia has been well studied. Few data are available about the pathology of such lesions in venous structures. Some reports of coronary artery or venous damage when radiofrqequency lesions are placed in branches of the coronary sinus have been made. Therefore, it is not surprising that lesions placed within small pulmonary veins may lead to a localized venous stenosis. A single stenosis would probably not have serious consequences. The problem seen in this study was that when all pulmonary veins are involved, significant pulmonary hypertension, which is potentially life threatening, can be the result.
It is unclear why only two of the patients in this series developed this problem. Both of them were studied at a single center, and it may be that the technique at that center was more aggressive in applying lesions in or near the pulmonary venous ostia. However, any technique that attempts to totally isolate sources of arrhythmia arising from the pulmonary veins will have to place lesions at least close to these ostia, and venous injury will be a potential complication of any such approach.
Although Robbins et al were successful in using balloon dilation for the lesions they had created, they do warn that the long-term efficacy of this treatment is unknown. Long-term studies will be needed before one can be sure if dilatation provides only temporary palliation or if a successful long-term outcome will be achieved in a high proportion of patients.
Catheter ablation of atrial fibrillation remains a highly investigational technique. Certainly, this paper should raise the sensitivity of physicians to the possible complications associated with these procedures. Careful follow-up after these procedures is essential.
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