Background:Constrictive pericarditis (CP) is characterized by impaired diastolic cardiac function leading to heart failure. Pericardiectomy is considered effective treatment for CP, but data on long-term clinical outcomes after pericardiectomy are limited.Methods and Results:We retrospectively investigated 45 consecutive patients (mean age, 59±14 years) who underwent pericardiectomy for CP. Preoperative clinical factors, parameters of cardiac catheterization, and cardiac events were examined. Cardiac events were defined as hospitalization owing to heart failure or cardiac death.Median follow-up was 5.7 years. CP etiology was idiopathic in 16 patients, post-cardiac surgery (CS) in 21, tuberculosis-related in 4, non-tuberculosis infection-related in 2, infarction-related in 1, and post-radiation in 1. The 5-year event-free survival was 65%. Patients with idiopathic CP and tuberculosis-related CP had favorable outcomes compared with post-CS CP (5-year event-free survival: idiopathic, 80%; tuberculosis, 100%; post-CS, 52%). Higher age (hazard ratio: 2.51), preoperative atrial fibrillation (3.25), advanced New York Heart Association class (3.92), and increased pulmonary artery pressure (1.06) were predictors of cardiac events. Patients with postoperative right-atrial pressure ≥9 mmHg had lower event-free survival than those with right-atrial pressure <9 mmHg (39% vs. 75% at 5 years, P=0.013).Conclusions:Long-term clinical outcomes after pericardiectomy among a Japanese population were related to the underlying etiology and the patient’s preoperative clinical condition. Postoperative cardiac catheterization may be helpful in the prediction of prognosis after pericardiectomy.