Diagnosis of cardiomyopathy is on the rise 

The number of patients diagnosed with cardiomyopathy has increased substantially over the past two decades. This is the finding of a new study from Uppsala University that mapped all cases of cardiomyopathy in Sweden. Despite identifying this increase, it is still unclear whether this is due to more people developing cardiomyopathy or to healthcare becoming better at diagnosing it.

Serious diseases of the heart muscle, more commonly known as cardiomyopathies, can lead to heart failure, arrhythmias and sudden death. Despite their serious nature, until now there has been a lack of comprehensive data on how common they are and how the patients affected fare. 
In a new study published in the Journal of the American College of Cardiology, researchers at Uppsala University mapped all cases of cardiomyopathy in Sweden between 2004 and 2023. 

“We can see that cardiomyopathy diagnoses have become more common and that they are associated with substantial excess mortality. The study indicates that we need to gain a better understanding of these diseases, to be able to detect them earlier, and develop more targeted treatments,” says Daniel Lindholm, cardiologist at Norrtälje Hospital and researcher at Uppsala University, who led the study.

Although the study shows that there has been an increase, it cannot answer whether this is actually due to more people suffering from cardiomyopathy. 

“We’ve become better at diagnosing cardiomyopathies over time, which could explain the increased incidence to some extent,” says Daniel Lindholm.

Diagnosis is on the rise

The study shows that the incidence of cardiomyopathy diagnoses more than doubled during the study period. The increase mainly concerns dilated cardiomyopathy (when the heart becomes enlarged) and hypertrophic cardiomyopathy (when the heart muscle thickens). In women, there has also been a marked increase in other cardiomyopathies, which probably reflects increased awareness of Takotsubo cardiomyopathy (stress-induced cardiomyopathy, also known as broken heart syndrome). 

High excess mortality with cardiomyopathy 

Cardiomyopathies were associated with high mortality, with mortality generally being slightly higher among men. However, mortality was 32 times higher than in the general population among the youngest women in the study, and 16 times higher among the youngest men.

“Young people have a very low expected mortality, and it is even lower among young women than among young men. So even though mortality is similar among young cardiomyopathy patients in absolute terms, excess mortality is higher among women, as young women in the general population have a lower expected mortality rate than young men.

Excess mortality decreased with increasing age, but even among the oldest patients, mortality was twice as high as in the general population.

“The substantial excess mortality highlights the great need to learn more about the underlying causes. We also need to get better at identifying patients in time and developing more specific treatment. The new knowledge from our study provides a clearer picture of the extent of the problem, which is a prerequisite for finding new treatments,” says Daniel Lindholm.

About the study: First national mapping

The researchers used data from the National Board of Health and Welfare’s health registers to identify all adults who had been diagnosed with cardiomyopathy in Sweden between 2004 and 2023. A total of 57,000 patients were included. Mortality was then compared with the general population using data from the Human Mortality Database, which collects information on mortality in developed countries.

The study was conducted by researchers at the Anders Wiklöf Institute of Cardiac Research at Uppsala University and was also supported by Norrtälje Hospital (Tiohundra AB).