instruction: count the number of patients who have been given the procedure for a catheter ablation of lesion of heart two or more times since 4 years ago.
response: SELECT COUNT(DISTINCT t1.uniquepid) FROM (SELECT patient.uniquepid, COUNT(*) AS c1 FROM patient WHERE patient.patientunitstayid = (SELECT treatment.patientunitstayid FROM treatment WHERE treatment.treatmentname = 'catheter ablation of lesion of heart' AND DATETIME(treatment.treatmenttime) >= DATETIME(CURRENT_TIME(), '-4 year')) GROUP BY patient.uniquepid) AS t1 WHERE t1.c1 >= 2