Akershus Cardiac Examination Study 1950 (ACE1950)

Background:

Atrial fibrillation (AF) is the most common heart rhythm disorder. The condition is associated with substantial mortality and morbidity from thromboembolism, heart failure and impaired cognitive function. AF plays a causal role in about 1/5 of ischemic stroke cases. An estimated 70,000 people in Norway have an AF diagnosis today. Most subjects with AF are older than 60 years. The absolute number of subjects with AF is increasing rapidly in the westernized world and is expected to triple between now and year 2050. Catheter ablation techniques for treatment of AF are improving; however, such treatment is expensive, not readily obtainable and long-term prognosis is uncertain. Secondary prevention of AF has proved difficult without anti-arrhythmic drugs; however "upstream" therapy for primary prevention of AF in subjects at risk of developing AF may be useful. Characterization of potentially modifiable risk factors for AF may therefore have substantial clinical importance.

Objectives:

The primary objective is to identify predictors for future AF development (clinical, biochemical, genetic, electrocardiographic and echocardiographic). The study will aim at identifying modifiable risk factors. Secondary objectives include assessment of prevalence and incidence of AF, as well as investigating clinical characteristics and comorbidity in the study population at baseline.

Methods:

ACE 1950 will be a large, observational, prospective, longitudinal, population-based cohort study. Subjects of either gender residing permanently in Akershus County and born in the year 1950 (approximately 6000 residents are of eligible age) will be invited to participate in the study. Participants will go through a thorough baseline examination, including a physical exam with height, weight and blood pressure measurements. Blood samples will be drawn for routine tests as well as more advanced biomarkers analysis. ECG and echocardiography will be performed. Self-completed questionnaires on medical history and quality of life will also be collected. The participants will then go through annual follow-up visits with new questionnaires and ECG, and will be encouraged to contact the study group if atrial fibrillation incidents occur.

Time schedule:

A comprehensive planning process, including preparation of protocol and applications, has taken place during 2011. The project is now awaiting ethical approval and is expected to start with study inclusion and baseline examinations early in 2012. This is expected to last for approximately 2 years. Baseline examinations are expected to be completed by 2013, and continuous follow-up of the participants will then begin. The first PhD degree is expected to be completed by the end of 2014. This large cohort study is expected to form the basis of a number of sub-studies and PhD degrees in years to come.

Scientific significance:

The most recent population-based studies on development of AF were launched up to 10-15 years ago, and did not, from the outset, study novel biomarkers or imaging techniques, nor were modern therapeutic modalities assessed. Consequently, a knowledge gap remains. We still do not know why prevalence figures differ so much between studies, or why men seemingly are more affected than women. A longitudinal study such as ours may answer more important questions, for instance, the relation of AF to other diseases such as dementia and diabetes. Moreover, it will be the most comprehensive atrial fibrillation population study ever performed in Norway.