New research was presented at Heart Rhythm 2015, the Heart Rhythm Society’s annual scientific sessions, from May 13 to 16 in Boston. The features below highlight some of the studies that emerged from the conference.

Physical Activity, AF, & Gender

The Particulars: Results of previous studies on the impact of physical activity on the risk of atrial fibrillation (AF) have been inconclusive in many investigations. Few analyses have assessed the effect of intensity of physical activity on AF, particularly with regard to gender.

Data Breakdown: Researchers performed a systematic review of 14 studies involving nearly 400,000 patients that reported on the relationship between physical activity and AF incidence. Among men, vigorous exercise increased the risk of AF, whereas moderate exercise lowered AF incidence. For women, moderate and high intensity physical activity both reduced subsequent risks of AF.

Take Home Pearls: Moderate exercise appears to reduce the risk of AF in men and women. However, vigorous exercise appears to reduce the risk of AF in women but increase this risk in men.

Measuring Activity in Patients With ICDs

The Particulars: Implantable cardioverter defibrillators (ICDs) automatically collect physical activity data in order to provide quantifiable and easily accessible measures of functional status. However, few studies have assessed the relationship of these measures with survival in this patient population.

Data Breakdown: More than 98,000 patients with ICDs were followed in a study to examine the association between survival and increments of 30 minutes of physical activity per day. After 4 years, the survival rate was about 90% among the most active patients when assessed at baseline, compared with a rate of 50% that was observed in the least active patients. Patients with 30 minutes per day less activity in a given month had a 48% higher risk of death when compared with patients who were more active in the same month.

Take Home Pearl: Physical activity appears to strongly correlate with survival following ICD implantation.

Primary Prevention ICDs Improve Survival in Women

The Particulars: Evidence suggests that implantable cardioverter defibrillators (ICDs) are commonly used in women as primary prevention, but females have a low rate of participation in trials assessing the effects of ICDs. The few analyses available on primary prevention ICDs in women have revealed inconsistent findings.

Data Breakdown: For a study, researchers compared the all-cause mortality rate of women with primary prevention ICDs with that of matched women without ICDs. All women were Medicare patients hospitalized for heart failure. An identical analysis was performed in men. Women with an ICD had a significantly lower mortality rate (hazard ratio [HR], 0.78) than those without an ICD. Findings were similar in men (HR, 0.76).

Take Home Pearls: Among Medicare patients hospitalized for heart failure, women with a primary prevention ICD appear to a have a significantly lower mortality rate than those without an ICD. This survival difference appears to be similar to the already established benefit of ICDs seen in men.

Age at Menopause Impacts AF Risk

The Particulars: Previous research indicates that early menopausal age is associated with a higher risk of cardiovascular disease (CVD) and stroke. However, whether age at menopause affects the risk of incident atrial fibrillation (AF) has not been well defined.

Data Breakdown: For a study, postmenopausal women without CVD or AF at baseline were followed for an average of 19 years for the development of new-onset AF. Women who experienced menopause at ages 44 to 50 had a significantly higher risk of AF than women with a menopausal age younger than 44. However, older age of menopause (>50 years) was not significantly associated with AF risk.

Take Home Pearls: Younger age at menopause appears to decrease the risk of AF. There may be a possible pathophysiological link between AF and duration of exposure to estrogen.

Arrhythmic Events Common in CKD

The Particulars: Previous studies indicate that patients with chronic kidney disease (CKD) who are on hemodialysis have a high risk of sudden cardiac death (SCD). However, the long-term incidence and prevalence of significant arrhythmias in this patient population has not been well established in clinical research.

Data Breakdown: Patients with CKD who were on dialysis and had a left ventricular ejection fraction greater than 35% were recruited for a study. Participants had an implantable cardiac monitor inserted to record SCD events and arrhythmias and were followed intensively. Unexpected SCDs occurred in 16% of patients, and each of these cases occurred during the longer interdialytic period; the terminal event was severe bradycardia with asystole. Overall, arrhythmia events were recorded in 86% of patients.

Take Home Pearl: The occurrence of SCD and significant arrhythmias appears to be substantially high in patients with CKD who are undergoing hemodialysis.