OBJECTIVES:

Cancer, and its treatments, can increase the risk of developing cardiac conditions such as Atrial Fibrillation (AF). For elderly Colorectal Cancer (CRC) patients, a comorbid AF diagnosis may affect treatment decisions and clinical outcomes. We aim to quantify the incidence of newly diagnosed AF in elderly CRC patients and the risk factors associated with it.

METHODS:

Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database, we identified patients with age ≥65 years, who were newly diagnosed with CRC between 2015 and 2019, and enrolled in Medicare Part A, B, and D for least 180 days before and 1year after the CRC diagnosis. These patients were followed up for 1 year to calculate the cumulative incidence of incident AF diagnosis. Logistic regression models were used to identify the baseline characteristics associated with subsequent AF diagnosis.

RESULTS:

This study included 17,304 elderly CRC patients. Of these, 2101 (12.1%) were diagnosed with incident atrial fibrillation during the first year of post-CRC diagnosis (annual cumulative incidence: 121.4 per 1000 patients). Compared to patients without AF, those patients with CRC who developed AF were older (Mean age: 79.2 vs.75.7 years), more likely to be male (50.7% vs. 44.8%), White (87.1% vs. 79.5%), have cancer in the colon rather than the rectum (78.5% vs. 73.6%) and in the early stages of CRC (71.5% vs. 43.8%). As expected, CRC patients diagnosed with AF had higher mean CHA₂DS₂-VASc scores compared to patients without AF (2.48 [SD: 0.93] vs. 2.30 [SD: 0.92]).

CONCLUSIONS: Diagnosis of AF among CRC patients is not uncommon. As in the general population, several demographic and clinical characteristics are associated with higher risks for AF in the CRC population. The clinical implications of these findings need to be explored.