【Objective】 To analyze the ventricular arrhythmias and shock events and their related factors in patients with implantable cardioverter-defibrillator (ICD). 【Methods】 Ninety-two patients were implanted ICD in The First Affiliated Hospital of Sun Yat-sen University from Mar 2004 to Sep 2012. All patients were followed-up regularly. The data combined with the clinical information of patients were analyzed retrospectively. 【Results】 Ninety-two patients were followed-up for 27.6±21.8 months averagely. 45 cases were primary prevention

47 cases were secondary prevention. 423 person-time follow-up were conducted. 37.8% primary prevention patients appeared ventricular tachycardia/ventricular fibrillation (VT/VF)

2.53 times/person-year averagely; 28.9% patients in that were given the shock treatment

0.44 times/person-year averagely. 59.6% secondary prevention patients appeared VT/VF

4.99 times/person-year averagely; 47.9% patients in that were given the shock treatment

averagely 1.41 times/person-year. In all patients

46 cases have ICD shock events (50.0%)

in which appropriate shock 35 cases (38.0%) and inappropriate shock 11 cases (12.0%). Total shock are 334 times

in which appropriate shock 198 times (59.3%) and inappropriate shock 136 times (40.7%); Inappropriate shock reasons include: Atrial fibrillation 92 times (67.6%)

supraventricular tachycardia 32 times (23.5%)

abnormal sensing 12 times (8.8%). The probability of both VT/VF and inappropriate shock events in patients with a history of atrial fibrillation are higher than patient without atrial fibrillation history (P < 0.05). 【Conclusion】 ICD primary prevent was benefit to patients to reduce sudden cardiac death(SCD); atrial fibrillation was not only the main reason of inappropriate shock

but also the hint to high incidence of VT/VF.