Burst Exercise Stress Testing in Catecholaminergic Polymorphic Ventricular Tachycardia

ImportanceCatecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited arrhythmogenic syndrome in which exercise stress testing is the primary method for provoking adrenergically mediated ventricular arrhythmias. Traditional exercise testing protocols, such as the Bruce protocol, may lack sensitivity, leading to missed diagnoses and undertreatment, whereas early pilot data suggest that a sudden high-intensity Burst protocol may better unmask arrhythmias.ObjectiveTo evaluate the diagnostic yield and therapeutic impact of the Burst exercise stress testing protocol compared with the traditional Bruce protocol in CPVT.Design, Setting, and ParticipantsThis retrospective cohort study included pediatric and adult patients evaluated for CPVT at 2 tertiary referral centers in Vancouver, British Columbia, Canada.Data were collected from May 2017 through May 2024, and data analysis was performed from May 2024 through April 2025. Of 38 screened patients, 28 were included who had undergone consecutive Bruce and Burst exercise tests, with available tracings and a diagnostic phenotype on at least 1 test. Arrhythmia severity was scored using the Ventricular Arrhythmia Score.ExposureType of exercise stress testing protocol (Bruce vs Burst).Main Outcomes and MeasuresThe main outcome was the Ventricular Arrhythmia Score (ranging from 0 = no premature ventricular contractions to 4 = nonsustained ventricular tachycardia). Other outcomes included changes in pharmacologic therapy and adverse events.ResultsThe cohort included 13 female patients (46%) and 18 probands (64%), including 23 (82%) with a causativeRYR2variant. Median (IQR) age at testing was 19.9 (14.8-33.9) years for Bruce testing and 21.0 (16.1-35.5) years at Burst testing. Bruce and Burst exercise tests were performed a median (IQR) of 1.3 (0.6-2.0) years apart, with all Burst tests performed on equivalent or intensified therapy. The Burst protocol provoked more severe arrhythmias in 20 of 28 patients (71%) with a higher median (IQR) Ventricular Arrhythmia Score (3 2-4 vs 1 1-2;P Conclusions and RelevanceIn this cohort study, the Burst exercise stress testing protocol detected a greater burden and severity of ventricular arrhythmias than the Bruce protocol in patients with CPVT, frequently prompting treatment escalation without observed safety concerns. These data suggest that incorporating Burst protocol exercise stress testing into the routine care of patients with CPVT is low risk and often informative.