Scar architecture as a structural biomarker of ventricular arrhythmias and sudden cardiac death in patients with hypertrophic cardiomyopathy: a cardiac magnetic resonance study
Hypertrophic cardiomyopathy (HCM) is a heart muscle disease in which the heart becomes abnormally thick, usually because of inherited (genetic) changes. Unfortunately, this condition can be associated with dangerous heart rhythm disturbances, such as ventricular tachycardia (VTs), which in some cases may lead to sudden cardiac death (SCD). However, it is important to remember that most people with HCM will never experience sudden cardiac death, especially when they receive regular specialist follow-up and appropriate treatment.
The implantable cardioverter-defibrillator (ICD) is currently the most effective treatment to prevent SCD in patients with HCM, as it can detect and stop life-threatening arrhythmias. In patients with HCM who have experienced and survived a life-threatening VTs, implantation of an ICD is generally straightforward and strongly recommended. The main challenge arises in patients who have never experienced this type of event. This is called “primary prevention”, meaning trying to prevent a first life-threatening arrhythmia before it happens.In these patients, the decision to implant an ICD relies on risk scores developed by the European Society of Cardiology (ESC) and the American Heart Association (AHA). However, these tools are not perfect, and improving our ability to identify patients who truly benefit from an ICD remains an important challenge.
In recent years, the presence and extent of scar tissue in the heart muscle —called myocardial fibrosis—have emerged as important risk markers. This scarring can be visualized using cardiac magnetic resonance (CMR) after a special contrast agent called gadolinium is injected. The scarred areas appear brighter on the images, a finding known as late gadolinium enhancement (LGE). Building on this concept, a new study by Dr. Francia and colleagues, published in European Heart Journal – Cardiovascular Imaging, investigated whether the way scar tissue is arranged within the heart, rather than simply how much scar tissue is present,could better predict dangerous arrhythmias. The study included patients from five cardiac centres across Europe (Italy, Spain, and Portugal).
Heart scars are not uniform. CMR allows doctors to distinguish between dense scar tissue (the “scar core”) and areas where scar tissue is mixed with healthier heart muscle (called the border zone). In some cases, these border-zone areas form narrow pathways, known as border-zone channels, that run through the dense scar tissue. These pathways may allow abnormal electrical signals to travel through the heart and trigger dangerous heart rhythm disturbances.
The study showed that patients with HCM often have this particular pattern of scar tissue, with a large proportion of border-zone tissue and relatively frequent border-zone channels. These channels were especially common in patients with more advanced disease, such as those with very thick heart walls or reduced heart pumping function. Importantly, the presence and amount of border-zone channels predicted the risk of ventricular arrhythmias even when traditional risk factors were taken into account, and significantly improved the performance of the existing ESC and AHA risk models.
In conclusion, this study suggests that the pattern and structure of scar tissue may be just as important as the amount of scar tissue present. Assessing scar architecture using cardiac MRI may help doctors better identify patients who are at higher risk of dangerous arrhythmias and who may benefit most from an ICD. Although more research is needed before this approach becomes routine in clinical practice, it could lead to more personalized care for people living with HCM.
Pietro Francia, Giulio Falasconi, Maria Beatrice Musumeci, Elena Biagini, Pedro Freitas, Diego Penela, José Tomás Ortiz-Pérez, Giacomo Tini, Matteo Sclafani, Maria Alessandra Schiavo, Rita Amador, Sebastiano Carli, Guido del Monaco, Cristina Panico, David Soto-Iglesias, Paula Franco-Ocaña, Raffaello Ditaranto, Andrea Saglietto, Julio Martì-Almor, Camillo Autore, and Antonio Berruezo.
European Heart Journal – Cardiovascular Imaging (2025) 00, 1–13 https://doi.org/10.1093/ehjci/jeaf297
Prepared by Raffaello Dilarante and Francesca Musso