Pulmonary vein antrum isolation causes atrial fibrillation to regress in the vast majority of patients with congestive heart failure.
PABA CHF, the first head-to-head trial with a six-month follow-up, randomized 71 patients with drug-resistant atrial fibrillation to receive one of two treatments, pulmonary vein antrum isolation ( PVI ) or AV node ablation with bi-ventricular pacing ( AVNA-BiV ). Of these patients, 35 underwent PVI and 36 underwent AVNA-BiV.
During AVNA-BiV, a catheter delivers electric current to the area of the heart transporting faulty electrical signals, creating a small patch of scar tissue to block those signals. The patient is left dependent on an implantable cardioverter defibrillator ( ICD ) or pacemaker. Although AVNA has been used clinically for about 25 years, the addition of the bi-ventricular ICD has become common only in the last three years in patients with heart failure.
During a PVI procedure, catheters inserted into the heart atria deliver radiofrequency energy to the pulmonary vein, eliminating the faulty electrical impulses. This creates a line of scar tissue that block the signals, effectively disconnecting the pathway of the abnormal rhythm. The PVI requires puncturing the heart and crossing over into the left atrium. PVI has been performed and refined almost exclusively at large academic medical centers during the last 10 years.
In the study, patients could continue on anti-arrhythmic drugs and PVI patients could have a second PVI procedure after two months based on physicians’ judgment.
People with heart failure are at increased risk of atrial fibrillation, the most common irregular heartbeat problem in the United States. Untreated or poorly controlled atrial fibrillation can lead to stroke and worsening heart failure.
Compared to AVNA-BiV patients six months after their initial procedure, PVI patients showed improvements on all the primary endpoints: their quality of life scores as measured by a questionnaire about daily activity limitations ( 61 vs. 79 ); their six-minute walk distances ( 345 meters vs. 301 meters ); and a higher ejection fraction, the measure of the heart’s pumping ability, ( 35 percent vs. 29 percent ). The ejection fraction for the AVNA-BiV group was close to the baseline ejection fraction for all patients in the study.
The results on the secondary endpoint, freedom from atrial fibrillation, were even more compelling: 89 percent of the PVI patients were free of atrial fibrillation, including 74 percent who were free of atrial fibrillation and antiarrhythmic medication. None of the AVNA-BiV patients were considered free of atrial fibrillation.
Researchers found that 42 percent of AVNA-BiV patients experienced worsening atrial fibrillation severity compared to no worsening in the PVI patients. In fact, 94 percent of the PVI patients moved to a better category, including the high number of PVI patients with and without anti-arrhythmic medication who had no atrial fibrillation at all. In comparison, only 6 percent of AVNA-BiV patients moved to a better atrial fibrillation category.
Andrea Natale, at the Cleveland Clinic in Ohio, said AVNA-BiV does not attempt to “cure” atrial fibrillation, but attempts to control the symptoms. However, PVI aims to eliminate the atrial fibrillation directly.
Both procedures carry the risk of infection and perforation, while PVI carries the further risk of stroke and pulmonary vein stenosis, or narrowing of the artery, Natale said. However, the only complication seen in this trial was mild, symptomless PV stenosis.
“ PVI leads to improvements in quality of life, functional capacity and ejection fraction versus AVNA-BiV in patients with symptomatic atrial fibrillation with heart failure,” Natale said. “At specialized academic centers, patients who have symptomatic atrial fibrillation should be considered for PVI first before AVNA-BiV.”
Source: American Heart Association ( AHA ) - Scientific Sessions, 2006
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