Long-term Follow-up Outcomes In Patients With Brugada Syndrome

Part oneClinical Characteristics and Long-Term ICD Follow-up Outcomes in Patients with Brugada SyndromeObjective:The risk of arrhythmia and sudden cardiac death (SCD) in patients with Brugada syndrome is not the same and the prognosis of patients with different risk factors is different, so we should take treatment measures to patients with Brugada syndrome individually.Methods:There were totally 98 patients confirmed with Brugada syndrome in our hospital during 1998 to 2014 and 75 of them were routinely followed up every 6 months. The clinical characteristics and prognosis were recorded.The initial ICD parameters were set according to conventional experience. The ventricular tachycardia (VT) zone was programmed to ventricular rate 150-188bpm/cycle length (CL) 400-320ms and the ventricular fibrillation (VF) zone was ventricular rate≥ 188bpm/CL≤320ms. The total events were recorded by ICD. If inappropriate shocks were discovered, the ICD parameters would be appropriately revised by electrophysiological (EP) experts.Results:Seventy-five Brugada syndrome patients (males 74 and female 1; mean age 41.4±12.2years) were followed up for mean 92±42months.During the follow up, four patients suffered SCD and the other 71 were alive. Nineteen patients implanted with ICD (one with SCD,15 with syncope and 3 without symptoms but electrophysiologic study induced VF) were all alive except one patient who did not replace the ICD after the battery depletion. Three of 56 patients without ICD had died during follow up and the others were alive without any accidents such as syndrome or SCD. Nine patients (47%) with ICD underwent VF terminated by ICD and 2 patients suffered VT terminated by ICD and the rest 8 patients did not experience any VT/VF. The risk factors of recurrent VT/VF in patients with Brugada syndrome were syncope associated with arrhythmia and family history of sudden death. There were 12 (63%) patients underwent inappropriate discharge and the main reason was supraventricular tachycardia (SVT). In these 12 patients, there were 4 patients (21%) underwent inappropriate discharge and never underwent any appropriate shocks due to VT/VF. A total of 342 VF/VT events were recorded by ICD and in which 236 (69%) events were "VF" while the other 110 (31%) were "VT". EP experts found that 216 (92%) episodes were true VF (CL 130-250ms) among of 236 VF episodes.185 VF episodes were terminated by one shock and 21 VF events were terminated by two or more shocks, and the rest 10 VF terminated spontaneously. Only 12%(13/110) VT events were true VT (CL 320-360ms) among of 110 VT episodes. Eight VT episodes were converted by antitachycardia pacing therapy (ATP) and 4 episodes were terminated by ICD shocks and the other one terminated spontaneously. The rest 97 VT episodes (88%) were SVT (CL 340-390ms). About 90% inappropriate shocks can be reduced by optimal programming (VF zone ventricular rate≥222bpm/CL≤ 270ms and/or VT zone ventricular rate 167-222bpm/CL 270-360ms) according to the characteristics of arrhythmia of every patient.Conclusions:Syncope associated with VA and history of sudden death was the risk factor of recurrent VT/VF in patients with Brugada syndrome.Patients without evidence of VA might not require immediate implantation of ICD. The most common complication of ICD was inappropriate shock due to SVT. Optimal ICD programming [VF zone ventricular rate≥222bpm (CL≤270ms) and/or VT zone ventricular rate 167-222bpm (CL 270-360ms)] with Wavelet discrimination function can dramatically reduce the frequency of inappropriate shock rate (about 90%).Part twoLow Dosage Quinidine Effectively Reduced Shocks in Brugada Syndrome Patients with an Implantable Cardioverter-DefibrillatorBackground:Only ICD has been proven to prevent sudden cardiac death (SCD) in Brugada syndrome (BrS) patients. However, ICD discharge, whether appropriate or inappropriate, leads to impaired quality of life and even increases rehospitalization. Quinidine might prevent the recurrence of ventricular arrhythmia (VA), however, the effects of low-dose quinidine for preventing spontaneous arrhythmias is less clear.Methods:In our cardiology center,10 confirmed BrS patients (all male, mean age 38.7±6.72 years) who underwent appropriate ICD shocks due to recurrent VAs were treated with quinidine (≤200mg/day) and followed regularly.Results:All of the patients underwent ICD shocks due to ventricular tachycardia (VT)/ventricular fibrillation (VF) before taking quinidine. A 24 hours distribution of VT/VF demonstrated that most of the events occurred in the sleeping time from 22:00 to 8:00. Quinidine prevented recurrence of VAs in 9 patients. The other one who took quinidine discontinuously because of anxiety suffered from less episodes of VA and after psychological guidance, he took quinidine 200mg/day and experienced no VA episodes from then on. In our series, only one patient suffered leukopenia related to quinidine. No other side effect was observed.Conclusions:Quinidine with a very low dose (≤200mg/day) well controlled VT/VF recurrence for a long-term period in Chinese BrS patients. Administration (at 21:00) according to the circadian distribution of VT/VF episodes might increase the efficiency and improve the patient’s tolerance.