High prevalence of cardiovascular comorbidity in multiple myeloma. A Swedish register study with matched controls

Multiple myeloma is a type of blood cancer that affects the plasma cells, which are the white blood cells responsible for producing antibodies to fight infection. This disease typically strikes later in life, with most people receiving a diagnosis around the age of seventy-two. Because the patients are older, they often carry other health conditions alongside the cancer, particularly those affecting the heart and blood vessels. These conditions, known as cardiovascular comorbidities, include issues like high blood pressure, irregular heartbeats, and heart failure. The relationship between the cancer and the heart is complex; the disease itself can strain the heart, and some of the powerful medicines used to treat it can also have side effects on the cardiovascular system. Understanding how common these heart problems are before treatment begins, and how often new ones appear during treatment, is crucial for keeping patients safe and helping them live longer.

Researchers in Sweden set out to map this landscape using a massive collection of national health records. They gathered data on nearly 8,700 patients diagnosed with multiple myeloma between 2008 and 2021. To ensure their findings were accurate and not just a reflection of general aging, they compared these patients to a group of over 34,000 people from the general population who were matched by age, sex, and where they lived, but who did not have the cancer. The team looked at medical records to see who had a history of heart disease at the moment of their cancer diagnosis and tracked what happened over the next two years. Their goal was to see if the cancer patients were more likely to have heart issues than their healthy neighbors, and whether developing new heart problems during treatment affected their chances of survival.

The study revealed that heart conditions were already very common at the time the cancer was found. Nearly half of the patients, specifically 45.8 percent, had a registered history of cardiovascular disease before they even started cancer treatment. In contrast, only about 35.7 percent of the matched control group had such a history. The most frequent issues were high blood pressure and an irregular heartbeat called atrial fibrillation. High blood pressure was found in roughly one-third of the patients, while atrial fibrillation affected about one in nine. These numbers were significantly higher than in the control group, suggesting that the burden of heart disease is a major part of the reality for people with this cancer. The problem was even more pronounced in the oldest patients; among those over eighty years old, nearly two-thirds had some form of heart condition at the time of diagnosis.

As the researchers followed the patients for two years after diagnosis, they found that new heart problems continued to appear at a much higher rate than in the general population. By the end of the two-year period, 60.7 percent of the cancer patients had experienced a cardiovascular event or had a new diagnosis, compared to just 27.3 percent of the control group. This included a sharp rise in new cases of atrial fibrillation, which affected 17.7 percent of the patients but only 8.5 percent of the controls. The situation was particularly stark for those who started the study with a healthy heart. Among the patients who had no history of heart disease at the time of their cancer diagnosis, 43 percent developed a new cardiovascular event within two years. This is a striking figure, as it means that nearly half of the patients who began treatment with a clean bill of cardiovascular health encountered a significant heart issue very quickly.

The presence of these heart conditions had a direct and measurable impact on how long patients lived. The data showed that patients who had heart disease at the time of their cancer diagnosis faced a higher risk of death compared to those who did not. This risk remained even after the researchers adjusted for age and other factors. Furthermore, for patients who started without heart disease, developing a new cardiovascular event during the two-year follow-up increased their risk of death by nearly 30 percent. The most common causes of death related to the heart among those who passed away were heart failure and irregular heartbeats. This suggests that managing heart health is not just a secondary concern but a critical factor in the overall survival of patients with multiple myeloma.

The researchers were careful to consider whether the high numbers were simply due to doctors looking more closely at cancer patients than at healthy people, a phenomenon known as surveillance bias. They analyzed when the diagnoses were made and found that while there was a spike in detections right before and after the cancer diagnosis, the rates of serious events like heart attacks and strokes remained significantly higher in the cancer group throughout the follow-up period. This indicates that the increased risk is real and not just an artifact of more frequent testing. The study also noted that modern treatments for multiple myeloma, which often involve combinations of drugs including immunomodulatory agents and proteasome inhibitors, are known to carry risks for the heart. While the study could not link specific drug regimens to specific outcomes because of limitations in the registry data, the sheer volume of patients affected points to a systemic issue.

Ultimately, this large-scale study paints a clear picture of a population that is highly vulnerable to heart disease. Almost half of the patients arrive at the clinic with existing heart conditions, and for those who do not, the risk of developing new problems is substantial. The findings highlight that the heart and the cancer are deeply intertwined in this disease. The authors conclude that there is an urgent need for better awareness and specific guidelines to manage cardiovascular health in these patients. By recognizing the high prevalence of these conditions and the increased risk of death they carry, doctors can potentially adjust treatment plans and monitor patients more closely, ensuring that the fight against cancer does not come at an unmanageable cost to the heart.