Levels of anxiety sensitivity may be important in choosing medical treatment for patients with heart failure and atrial fibrillation (AF), Montreal Heart Institute researchers today told the Canadian Cardiovascular Congress 2010, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

Heart and Stroke Foundation researcher and lead author Nancy Frasure-Smith, PhD explained that anxiety sensitivity is the degree to which a person is frightened by bodily sensations and symptoms, particularly those associated with anxiety.

"For most people, sweaty palms and an increasing heart rate are simply unpleasant symptoms that occur in stressful situations, for others these same symptoms are interpreted as a sign of impending doom," says Dr. Frasure-Smith. "People with high anxiety sensitivity tend to magnify the potential consequences of their anxiety symptoms, leading to an increase in anxiety and its symptoms in a spiralling increase of fear and worry."

While anxiety sensitivity is known to predict the occurrence of panic attacks in cardiac and non-cardiac patients, and is associated with greater symptom preoccupation and worse quality of life in patients with AF, it has not been previously studied as a predictor of cardiac outcomes.

These results are based on a sub-study from the Atrial Fibrillation and Congestive Heart Failure Trial (AF-CHF), a randomized trial of rhythm versus rate control treatment strategies whose results were presented at the Canadian Cardiovascular Congress in 2008. AF-CHF, which was funded by the Canadian Institutes of Health Research, was directed by Dr. Denis Roy, cardiologist at the Montreal Heart Institute (MHI) and vice-dean of the Université de Montréal's faculty of medicine.

Prior to randomization 933 AF-CHF study participants completed a paper and pencil measure of anxiety sensitivity. They were then randomly placed in one of two treatment groups: a 'rhythm' group that was treated with anti-arrhythmic medication and cardioversion (an electric shock to convert an abnormal heart rhythm back to normal rhythm); and a 'rate' group that received medication to help keep people's heart rates within a certain range.

Participants were followed for an average of 37 months. Results showed that, as in the overall AF-CHF trial, the majority of patients had as good a prognosis with the rate control strategy as with the rhythm control approach. In contrast, patients with high anxiety sensitivity had significantly better outcomes if they were treated with the more complicated rhythm control strategy.

"Increased emotional responses to AF symptoms in people with high anxiety sensitivity may lead to increased levels of stress hormones making them more vulnerable to fatal arrhythmias and worsening heart failure," says Dr. Frasure-Smith, a researcher at the MHI, adjunct professor of psychiatry at University of Montreal and professor of psychiatry at McGill University.

"For AF-CHF patients with high anxiety sensitivity maintenance of normal sinus rhythm appears to be important."

AF is a common type of heart arrhythmia which affects approximately a quarter of a million Canadians, including up to forty percent of individuals with congestive heart failure.

During AF the upper chamber of the heart (the atria) beats irregularly and very rapidly. Patients may experience palpitations, shortness of breath or chest pain. While by itself AF is usually not fatal, it increases the chances of heart failure and stroke. When AF and heart failure occur together, there is an increased risk of fatal outcomes, so finding the best treatment for each patient is extremely important.

"While the study − a sub analysis of a larger trial – is not definitive in itself, it does raise interesting questions," says Heart and Stroke Foundation spokesperson Dr. Beth Abramson. We tend to underestimate the power of the mind in patients on powerful heart medications. Mental well being however is an important aspect of care for all heart patients."