Europeans with cardiomyopathy have more ICDs and gene testing than expected

9th September 2015

European cardiomyopathy patients have more internal defibrillators and more genetic testing than expected, according to a small study of people seen at large treatment centres across the continent.

The study looked at more than 1,000 people with the disease taken from the European Society of Cardiology (ESC’s) cardiomyopathy registry which covers patients seen at 27 medical centres in 12 countries.

The study’s principal investigator Professor Perry Elliott, from the inherited heart disease team at the Barts Heart Centre and vice-president of Cardiomyopathy UK, said the study was the most representative snapshot of real world practice in the disease in Europe and had shown a higher than expected use of defibrillators and gene testing. He was speaking at the ESC's Congress in London.

Centres taking part in the registry were required to have dedicated cardiomyopathy clinics staffed by experienced medical and nursing teams and access to genetic testing with skills in interpreting the results. Each centre was asked to contribute up to 40 consecutive patients aged over 18 years during a 12 month period.

Cardiomyopathy registry

In 2012 and 2013, researchers looked at 1,115 people on the registry with hypertrophic (HCM), dilated (DCM), arrhythmogenic right ventricular (ARVC) and restrictive (RCM) cardiomyopathy.

The commonest cardiomyopathy was HCM (61%) followed by DCM (31%), ARVC (5%) and RCM (3%). A total of 316 patients (28.3%) had received an implantable cardioverter defibrillator (ICD). The proportion was highest in patients with ARVC (57.6%) and lowest in those with RCM (6.9%). The majority of ICDs were for those thought to be at risk of having a dangerous heart rhythm. Some 8% of patients had a pacemaker alone and 5.2% had a biventricular (CRT) device.

"Nearly 60% of patients with ARVC had an ICD which is extremely high," said Professor Elliott. "We don't fully understand why that is yet. It may be because referral centres see the highest risk patients or therapy may be more aggressive in the real world than guidelines recommend, with a lower threshold for putting in a defibrillator than anticipated."

Also striking was the finding that 462 patients (41.4%) had genetic testing, with a disease-causing mutation reported in 236 (51.1%).

Professor Perry Elliott

Professor Elliott

"This is the first time that data has been collected on the scale of genetic testing in patients with cardiomyopathies," said Professor Elliott. "The results show that the use of genetic testing is high and efficient, with more than half of the tests yielding a positive result."

Nearly 60% of HCM and ARVC patients and 70% of DCM patients were men. Slightly more than half of RCM patients were women. Professor Elliott said: "Most of the diseases were more common in men, which has been described before, but is poorly understood. It could be that men have more severe disease or there may be systematic underdiagnosis in women."

The registry showed that one third of patients with a cardiomyopathy were diagnosed either incidentally or through family screening. "Cardiologists, GPs and other physicians need to be alert to the fact that these are quite common conditions that can appear through different routes," said Professor Elliott.

He concluded: "Patients with cardiomyopathy need intensive investigation using specialised diagnostic tests. Many of the findings reported, including the very high use of ICDs in ARVC and the high yield from genetic testing, will be examined in sub-studies and in the long-term registry which will also include non-referral centres, centres outside Europe and in young patients.”