Monday, February 12, 2018

New imaging based biomarker to predict success of atrial fibrillation treatment

Researchers report successful use of biomarker based on heart imaging to predict the usefulness of catheter ablation to treat atrial fibrillation (Afib). Researchers analyzed the level of dys-synchrony in the left atrium as useful biomarker for success of the catheter ablation. The study is published in the Journal of the American College of Cardiology: Cardiovascular Imaging.

Atrial fibrillation, diagnosed in 3.4 million Americans and the most common heart rhythm condition in the United States, is marked by irregular and sometimes extremely rapid heart rates that cause fatigue and shortness of breath, and significantly increase the risk of heart failure and stroke. Treatments include drugs to regulate the electrical pulses in the upper chambers of the heart and  increasingly catheter ablation. The procedure involves general anesthesia and imaging guided use of a wire catheter threaded through a vein to the heart to make scores of tiny burns of tissue in which the irregular heartbeats arise. Though catheter ablation procedure is effective in reducing symptoms, there is an estimated 20 to 30 percent failure rate, and cardiologists have long sought various biological or anatomical factors to help them determine in advance which patients are the best candidates for ablation.

"In our study, we found that the best indicator of success is how in sync the left atrium chamber of the heart is when it relaxes," says Luisa Ciuffo, M.D., a postdoctoral fellow in the Division of Cardiology at the Johns Hopkins University School of Medicine. "Diseased, damaged hearts with a lot of scar tissue don't contract and relax at the same time throughout the atrium because it is more difficult to rhythmically contract the thicker, tougher damaged tissue." The analysis to determine the level of dys-synchrony in the left atrium

For the study, designed to identify the best predictors, the researchers used data from 208 atrial fibrillation patients admitted to The Johns Hopkins Hospital. Some 29 percent of the patients were women and the average age of all patients was 59. Prior to the ablation, each subject underwent computed tomography scans or MRIs of their hearts and were followed for an average of 20 months to assess recurrence of Atrial fibrillation or Afib, including a faster than normal heartbeat or an irregular heartbeat lasting longer than 30 seconds. Atrial fibrillation recurred in 101 patients.

The researchers then analyzed various characteristics of the imaging scans from 208 people in a subgroup: 107 of the people with successful ablations compared to 101 of those with failed ablations. Overall, the Johns Hopkins researchers found that patients with recurrent atrial fibrillation had on average more preoperative dys-synchrony throughout the left atrium than those who had successful ablations (3.9 percent versus 2.2 percent), with the higher value indicating more diseased atrium. In a second part of the study researchers wanted to study level of dys-synchrony that would predict success of treatment. They used cut off value of 2.86 percent and found that this model had 76% sensitivity and 81% specificity.

The researchers caution that a more randomized and controlled clinical trial is needed before doctors can reliably use their cardiac imaging analysis routinely with patients, but if confirmed, they say the method should reduce ablation procedures unlikely to work, along with the procedures' substantial costs and complication risks.

"We believe we are developing a tool that can help with personalized decision-making to help refine patient selection and thus reduce the failure rate by saving candidates with low potential benefit from futile procedures and complications," says senior author Hiroshi Ashikaga, M.D., Ph.D., assistant professor of medicine at the Johns Hopkins University School of Medicine. Although the risk of complication is small, about 6 percent with ablation, there is still the chance of puncturing the heart or forming a fistula.

Citation: Ciuffo, Luisa, Susumu Tao, Esra Gucuk Ipek, Tarek Zghaib, Muhammad Balouch, Joao A.c. Lima, Saman Nazarian, David D. Spragg, Joseph E. Marine, Ronald D. Berger, Hugh Calkins, and Hiroshi Ashikaga. "Intra-Atrial Dyssynchrony During Sinus Rhythm Predicts Recurrence After the First Catheter Ablation for Atrial Fibrillation." JACC: Cardiovascular Imaging, 2018. doi:10.1016/j.jcmg.2017.11.028.

Funding: NIH/National Heart, Lung, Blood Institute, W.W. Smith Charitable Trust, Magic That Matters Fund for Cardiovascular Research, Zegar Family Foundation, Edward St. John Foundation, Roz and Marvin H Weiner Family Foundation.

Adapted from press release by John Hopkins Medicine.
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