Research led by a team of investigators from the Universities of Oxford and Virginia, together with 42 other centres across North America and Europe, has found that patients with hypertrophic cardiomyopathy (HCM) may have distinct abnormalities in the heart muscle based on the presence or absence of a genetic mutation.
HCM is an inherited disease, where the heart muscle grows abnormally thick. It is the number one cause of sudden death in young adults and athletes and may also cause symptoms such as chest pain, breathlessness, palpitations and blackout. Genetic testing has become the standard of care in the management of HCM patients, with up to 40% seen to harbour a disease-causing gene mutation. The risk of sudden cardiac death has been reduced due to the development of the Implantable Cardioverter Defibrillator (ICD), a device that can abort sudden cardiac arrest. However, the insertion of an ICD is not without risks, so clinicians need to select the right patients (with the highest risk from the disease) who are most likely to benefit from this therapy. Recently a number of studies have suggested that the extent of scar within the heart muscle, as detected on cardiac magnetic resonance imaging (CMR), can be a powerful prognostic marker for HCM patients. However, many of these studies looked at patients in whom outcomes had already happened (retrospective studies) which may introduce bias in reporting.
The HCM registry (HCMR) study is a 14 million dollar National Heart Lung and Blood Institute (NHLBI)-sponsored study led by Professor Stefan Neubauer, from the University of Oxford, and Professor Christopher Kramer, from the University of Virginia, primarily designed to improve existing risk stratification strategies in HCM patients and to understand the natural history of this disease using CMR. This prospective multi-centre registry study will integrate advanced CMR data, highly sensitive blood biomarkers, genetics - for which Professor Hugh Watkins from Oxford provides the core expertise - and clinical information from 2755 HCM patients, to better predict the risk of sudden death, heart failure and arrhythmias in HCM patients. The baseline results of HCMR, recently published in the Journal of American Cardiology, revealed that HCM patients can broadly be divided into two groups. Those who carry a genetic mutation tended to have a greater burden of scar in their hearts, while those who did not, were found to have less scar but more outflow obstruction. The burden of scar on CMR also correlated with blood biomarkers of risk such as NT-BNP and troponin.
Professor Stefan Neubauer, first author of the manuscript and Director of the Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, said: “The HCMR study provides a unique resource of clinical, imaging, genetic and blood biomarkers that should, in future, change the way we make decisions about ICD implantations in patients with HCM”
A major strength of the HCMR study is the rich dataset of clinical, imaging, genetic and blood biomarkers obtained from this well-designed and carefully planned prospective study of HCM patients, which will ultimately help to provide a more accurate assessment of risks in HCM patients. Further studies on novel risk prediction models incorporating all these data are now awaited, once sufficient clinical outcomes have occurred.
(Image credit: Dr Betty Raman)