Stroke is the third most common cause of death and the leading cause of disability in Ireland. Around one-in-three strokes in Ireland are due to atrial fibrillation (AF). 

A major Irish research project is looking at a more effective way of screening for AF in older patients. The aim of the study is to detect a greater number of at-risk cases in the over 60s, thereby reducing stroke incidence and related disability and saving the health service considerable resources.

Strokes associated with AF are usually of greater severity, have poorer functional outcomes and lead to longer hospital lengths of stay. The key to prevention of strokes linked to AF is detection of irregular heart rhythm and management with anticoagulants. However, according to consultant geriatrician and one of the principal investigators in the study, Dr Ronan Collins, detection of AF can be challenging as it is often ‘silent’ until stroke occurs. 

AF is often asymptomatic and intermittent in nature, but whether intermittent or persistent, the risk of stroke is the same, with an overall increased risk of five to seven fold when the patient has AF. Factors that increase the risk include diabetes, hypertension, heart failure, age, sex and a history of previous stroke or TIA.

Dr Collins points out that checking a person’s pulse for signs of AF is not reliable and while the condition can be detected by ECG, this too is limited in that it is just ‘a point in time’ record of a person’s heart rhythm.

“AF-related strokes are completely preventable. Atrial fibrillation is detectable and occurs in around 5% of the population aged over 60 and maybe more than 10% in over 80s. However, while detection of AF would fulfil the Junger Wilson WHO criteria for feasibility of health screening, there has been limited international and no Irish evidence to date on the feasibility of systematic screening using prolonged monitoring.”

Where AF is suspected, the European Society of Cardiology (ESC) recommends performing an ECG, followed by prolonged periods of 24-hour and up to seven-day ECG monitoring where AF is suspected. To date, this has been found to be difficult in practice due to the cumbersome nature of current monitoring equipment but technology is becoming more patent friendly, accessible in community settings and able to monitor for prolonged periods. 

The study in which Dr Collins is involved is using a monitor called Zensor by Northern Irish company Intelesens. Zensor is a lightweight five-day monitor that can be worn in the community, removed easily for washing and showering etc, and whose results can be filtered to rhythm specification, easily uploaded to a digital record and analysed remotely. The researchers hope that this will prove to be a more efficient and easier way to detect AF and are examining the feasibility of population screening in an a key risk group.

The study is looking at two at-risk cohorts – over 60s with two of the risk factors of hypertension, diabetes and heart failure, and over 75s with one of those risk factors.

The researchers say by examining this cohort of 350 patients, the study aims to have an impact on stroke prevention through the detection of unknown cases of AF and commencement of treatment, and also to inform public health strategy on screening for AF in future.

According to Dr Collins, who is a consultant at Tallaght Hospital,  an effective AF screening programme has the potential to prevent up to 2,000 strokes per annum in Ireland, thereby avoiding a great deal of death and disability and reducing the social and economic burden of stroke.

“What we are trying to find out in the study is that if you did have a screening programme, who we would screen and what would the pick-up rate be? We have hypothesised that people over the age of 60 with the common risk factors might be most likely to have AF but you might get more pick-up rate targeting over 75s .”

“We hope to ascertain what the incidence of AF is in these two perceived high-risk cohorts. We are trying to garner some useful data which could tell us whether if we were to screen people systematically, what the rates of AF would be in perceived high-risk groups.”

Dr Collins believes that feasibility-wise, AF screening in this cohort is possible and could also be cost-effective. To date around 200 people have been recruited to the screening study and have been screened, and the interim results were presented to the International Association of Geriatrics and Gerontology meeting in Dublin in April.

These showed an overall prevalence of 11% of new atrial fibrillation in the screened population.

The study has received bursary funding from the Irish Heart Foundation and unrestricted educational grants from the pharmaceutical industry. Staff for the day-to-day running of the study have been provided through the company Clinical Research Ireland and it has collaborated with the Wellcome Trust-HRB Dublin Centre for Clinical Research.

The principal investigators are Dr Collins, consultant geriatrician and director of stroke services at Tallaght, and Dr Robert Kelly, consultant cardiologist and director of cardiology at the Beacon Hospital.