Idiopathic versus Provoked Renal Infarction: Characteristics and Long-Term Follow-Up of a Cohort of Patients in a Tertiary Hospital

Background: There is limited evidence on the etiology and outcomes of renal infarction. A provoking factor is identified only in one- to two-thirds of patients. Methods: This is a retrospective observational study. The clinical characteristics and outcomes of patients with acute renal infarction were studied; the sample was divided into two groups according to the presence of at least one provoking factor at the time of diagnosis (atrial fibrillation, flutter, major thrombophilia, or renal artery malformations). Results: The study comprised 59 patients with a mean age of 63 (±16.7) years and a follow-up period of 3.1 (±2.8) years. An identifiable provoking factor was found for 59.3% of the renal infarctions at the time of diagnosis, and atrial fibrillation was the most frequent one (in 49.2% of all patients). Renal impairment was found in 49.2% of the patients at diagnosis and in 50.8% of the patients 6 months after the event (p = 0.525). When compared with the idiopathic group, the patients with provoked infarction were older (69.8 vs. 57.9 years, p = 0.014) and had a higher rate of recurrence of arterial thrombosis during follow-up (18.8 vs. 0%, p = 0.028), but there were no differences in the rest of the baseline characteristics or in mortality rates. Six patients (10.2%) in the idiopathic group were diagnosed with atrial fibrillation during follow-up. Conclusions: Atrial fibrillation, both at diagnosis and at follow-up, is the most common identifiable cause of renal infarction; however, a significant number of patients are idiopathic, and these are younger, but they have a similar burden of cardiovascular disease and a lower risk of arterial recurrence.