Clinical presentation and short-term effect of hydroquinidine in Brugada syndrome patients included in the QUIDAM study

Introduction: QUIDAM is a French national multi-center prospective study, designed to evaluate the efficacy of hydroquinidine (HQ) in decreasing arrhythmic events in patients affected by the Brugada Syndrome (BrS). We described the main clinical features of our included patients and the short term effect of HQ in this population. Methods: QUIDAM is a double-blind randomized crossover study of two 1.5 year periods (HQ versus placebo) in patients affected by the BrS and implanted with an ICD. BrS ECGs were submitted to an expert committee to confirm the BrS type 1 diagnosis. Patients with a confirmed BrS were tested for HQ sensitivity during inclusion. An ECG was performed before and 3 hours after ingestion of HQ. Results: Among the 77 patients files submitted to the scientific committee, 15 ECGs were not considered to be diagnostic for the BrS and 5 withdrew their consents before inclusion. PR interval 181±32 ms vs 185±31 ms, QRS duration 104±18 ms vs 105±20 ms and ST-segment elevation 2±1 mm vs 2±2 mm were not significantly modified after HQ ingestion. On the contrary there was a significant lengthening of the QTc interval, 403±29 ms vs 415±31 ms (p-value<0.05) and a lengthening of the T(peak)-T(end) interval from 76.6±16.6 ms before HQ to 87.2±23.6 ms in V5 (p<0.001). One patient showed a 50 ms lengthening of the QTc interval and was then considered to be hypersensitive for HQ. No other signs of HQ intolerance were reported. Conclusions: These results demonstrate that even in tertiary centers involved in the treatment of BrS patients, the diagnosis is difficult. We underlined also that HQ treatment did not changed the ST segment elevation and prolonged the T(peak)-T(end) duration in a short period.