By Madeline Kennedy (Reuters Health) – – For overweight and obese people with a common heart rhythm problem, improving cardiovascular fitness with exercise may help to eliminate symptoms, a recent Australian study found. Participants with the greatest improvements in their cardio fitness were less burdened by symptoms of the arrhythmia, known as atrial fibrillation, and more likely to survive symptom free during the study, compared to those who had smaller or no fitness improvements. A possible side effect of the cardio exercise regimen, weight loss, may have also contributed to the improvements, researchers say.