Factors Affecting the Development of Atrial Fibrillation and Atrial Flutter (AF) Following Autologous Hematopoietic Stem Cell Transplantation (auto-HSCT).

Background: The use of auto-HSCT has expanded to include older patients. Age is a risk factor for the development of AF in the general population. As more elderly patients undergo auto-HSCT, the risk of developing AF post-transplant may also increase. The development of AF may increase morbidity, may prolong hospitalization, and may increase the cost of hospitalization. However, few data exist evaluating the factors that contribute to the development of AF following auto-HSCT. At our institution, we have observed a large number of patients with this complication. Therefore, we performed a retrospective case-control study to determine the incidence of AF following auto-HSCT and to determine risk factors associated with the development of AF.

Patients and Methods: We performed a chart review on all patients at our institution who received an auto-HSCT from November 1999 to May 2004. Cases were identified by reviewing EKGs performed post-transplant. Controls consisted of patients with similar age, year of transplant, and underlying hematologic malignancy. The following variables were examined for their association with AF: age, sex, diagnosis, disease stage at transplant, conditioning regimen, year of transplant, previous medical history including cardiac history, pre-transplant cardiology work-up, and electrolyte abnormalities immediately following auto-HSCT. Patients who developed AF were compared to controls. Multivariate logistic regression was done to evaluate the factors associated with the development of AF.

Results: During the study period, 44 patients developed AF at a median of four days (range days 1–9) following auto-HSCT; incidence of 8.5%. We identified 516 patients who did not develop AF who had auto-HSCT in the same time period. Of these, 179 patients with similar characteristics were used as controls. The following variables were associated with developing AF in the multivariate model: age at transplant; median age 63 yrs (50–72) for cases vs 57 (49–72) for controls (p<0.001), abnormal renal function as determined by serum creatinine (p=0.008), history of previous arrhythmia (p<0.001), and a history of mediastinal irradiation (p=0.003). Although not significant in the multivariate model, we observed that 45% of the patients who developed AF had increased left atrial size on a pre-transplant echocardiogram as opposed to none in the controls (p<0.001). There was no difference in the length of hospital stay between the cases and controls (p=0.13). We did not detect a significant difference in the 100d survival between those who did and did not develop AF (90% vs 96%, p=0.25). However, patients who did not develop AF had a better overall survival (Log-rank p=0.04).

Conclusions: Patients with older age, elevated serum creatinine level, history of previous arrhythmia, or history of previous mediastinal irradiation are more likely to develop AF following an auto-HSCT. Future studies should investigate whether interventions such as prophylactic beta-blockers can decrease the incidence of AF following auto-HSCT.