The Choice of Anticoagulant at First Recurrence Does Not Alter the Risk for the Second Recurrence

Introduction: Venous thromboembolism (VTE), encompassing deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major public health hazard, with up to 30-50% of patients with unprovoked VTE experiencing a recurrent VTE event. These recurrent VTE events are associated with significant morbidity and mortality. However, transition strategies to second-line anticoagulation regimens following the first recurrence on anticoagulation have not been well studied. We sought to examine whether rates of the second VTE recurrence were different in those patients who changed their anticoagulation regimen from those who did not .

Methods: With an IRB approval for the study, we created a database of all patients 18 years and older diagnosed with the first recurrent VTE at a large tertiary academic hospital between January 1, 2010, and December 31, 2019. The collected data was de-identified and compiled in a secure, standardized institutional database. We assessed the anticoagulation status at the time of and immediately following the first VTE recurrence, and identified patients who were switched to a different anticoagulant regimen. We used Fisher's exact test to evaluate proportions. Statistical significance was set at p<0.05.

Results:We identified 138 patients with the first VTE recurrence. Of these patients, 114 (83%) developed DVT, 7 (5%) PE, and 17 (12%) both DVT and PE. Mean age was 63 years at the time of first VTE; 70 (51%) were female. Racial/ethnic representation was 84 (61%) White, 46 (33%) Black, and 133 (96%) non-Hispanic. The majority of patients had cardiovascular risk factors, including hypertension 80 (58%), hyperlipidemia 44 (32%), ordiabetes 40 (29%). Among 138 patients, 32 (23%) had active cancer, May-Thurner syndrome or inferior vena cava (IVC) atresia were reported in 13 (9%) of cases, and 21 (17%) underwent IVC filter placement at the time of the first VTE recurrence. The median follow-up time after diagnosis of a second VTE was 5 years.

Following the first VTE recurrence, 19 (14%) of patients switched to a different anticoagulant agent, 7 (5%) had the dose of the anticoagulant adjusted, 1 (0.7%) was given a different INR target, and one had a change in the frequency of administration. The second VTE occurred in 49 (46%) patients who remained on the same anticoagulation regimen and in 3 (16%) who had the agent changed, in 5 who had dose of anticoagulant changed, in 1 (100%) each who had frequency or INR target changed.

The association between unprovoked first VTE and the development of the second VTE was not significant (p= 0.85, Fisher's exact test). 49 (36%) of patients had at least one bleeding episode requiring the interruption of anticoagulation or hospitalization. Of those, 43 (88%) occurred while on an anticoagulant.

Conclusion: The choice of an anticoagulant regimen after the first VTE recurrence does not impact the rate of the second recurrence.