According to the German Heart Foundation, up to 60 per cent of patients develop what is known as post-operative atrial fibrillation after heart surgery. This causes the heart to beat irregularly and often too quickly. It usually occurs within the first four days after surgery. Those affected often feel tired and dizzy, suffer from chest pain, shortness of breath or even fainting spells. Postoperative atrial fibrillation is one of the most common complications after heart surgery.
Researchers from Göttingen University Medical Centre (UMG) and Heidelberg University Hospital (UKHD) have jointly discovered a new way to more accurately predict the risk of dangerous cardiac arrhythmias after heart surgery under the leadership of Prof. Dr. Niels Voigt, Professor of Molecular Pharmacology at the Institute of Pharmacology and Toxicology at UMG, and Dr. Dr. Stefan Kallenberger, Head of the Systems Medicine Working Group at the BioQuant Centre at Heidelberg University. Together with national and international university partners, the researchers were able to show that patients with a particularly high risk of postoperative atrial fibrillation can be identified much more reliably if measurements of calcium movements in the heart muscle cells are added to the known clinical risk factors such as age or pre-existing conditions. After all, calcium plays a crucial role in the heart's pumping function: It provides the mechanical movement that allows the heart muscle to contract and pump blood through the body. Calcium movements are determined directly during surgery. If there is an increased risk of postoperative atrial fibrillation, preventive measures can be taken. The research project was financially supported by the German Centre for Cardiovascular Research (DZHK) and the Göttingen Cluster of Excellence ‘Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells’ (MBExC).
‘Our work shows how important it is to intelligently link molecular data and clinical information. This provides a more accurate picture of individual risk and thus the opportunity for tailor-made therapies,’ says Prof. Voigt, last author of the study.
The study included clinical data from a total of 558 patients who underwent heart surgery at the university hospitals in Göttingen and Essen. All study patients had a stable heart rhythm prior to surgery. This inclusion criterion allowed the research team to specifically investigate which factors associated with the surgery lead to this complication.
Calcium concentration as a precursor
During the heart operations, the cardiac surgeons took tiny tissue samples from the right atrium. The researchers used these samples to examine calcium processing in the heart muscle cells, a crucial process for the regular beating of the heart. To do this, they isolated individual heart muscle cells in the laboratory. Using the patch-clamp technique, a highly sensitive method in which extremely fine glass electrodes are applied to a single cell, they measured electrical currents and calcium movements in the cells. This enabled the researchers to determine exactly how the heart muscle cells absorb and release calcium.
Under the direction of Dr Kallenberger, the team at Heidelberg University Hospital evaluated the clinical and cellular data. The analyses showed that calcium concentration during cardiac contraction provides a particularly reliable indication of whether atrial fibrillation will occur after surgery. ‘We were able to show for the first time that this risk can be detected in the heart muscle cells even before the procedure,’ says Dr Funsho Fakuade, first author of the study, member of the Hertha Sponer College of the MBExC and postdoctoral researcher in Prof. Voigt's working group.
Co-first author Dr Judith Gronwald, assistant physician at the Clinic for Cardiology and Pneumology at UMG, adds: ‘This combination of laboratory and clinical data can be a real benefit for patients. It will enable us to take targeted preventive measures in future and thus prevent complications before they arise.’
Original publication:
Cytosolic calcium handling signature: integration with clinical predictors enhances prediction of post-operative atrial fibrillation. Fakuade et al., European Heart Journal (2025), DOI: https://doi.org/10.1093/eurheartj/ehaf609
