Atenolol is not effective in reducing ventricular arrhythmia severity on exercise stress test in patients with catecholaminergic polymorphic ventricular tachycardia

 

Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for malignant ventricular arrhythmias during exercise and emotions which may lead to sudden cardiac death. Beta-blockers (BB) are the mainstay of therapy in patients with CPVT, but studies comparing the efficacy of different types of BB are scarce. Our objective was to determine the efficacy of different types of BB in reducing the ventricular arrhythmia (VA) severity on exercise stress test (EST) in patients with CPVT.

Data was derived from the International CPVT Registry, a large retrospective cohort study. We included patients who had an EST before (pre-EST) and after start of BB (post-EST). We divided the cohort into five groups based on the first prescribed BB and compared pre-EST and post-EST.

We included 428 patients (median age 18.5 [11.7–39.6] years, 240 (56.%) female), 155 (36.2%) probands) of whom 38 (8.9%) used atenolol, 131 (30.6%) bisoprolol, 82 (19.2%) metoprolol, 124 (29.0%) nadolol and 53 (12.4%) propranolol. Sex and history of aborted cardiac arrest were similar in all groups. The age at start of BB differed (p<0,001): patients using bisoprolol were oldest (35.0 [15.7–35.3]) while patients using propranolol were youngest (12.3 [8.8–24.9]). Median daily BB dose in mg/kg was: 1.0 [0.8–2.3] for atenolol, 0.06 [0.05–0.10] for bisoprolol, 0.9 [0.6–1.5] for metoprolol, 1.1 [0.9–1.6] for nadolol and 1.5 [1.1–2.8] for propranolol. Resting heart rate on pre-EST and post-EST was similar in all groups. Patients using metoprolol had a significantly higher maximum heart rate post-EST compared to nadolol and propranolol (161±18 vs 136±19 and 130±22 bpm, p=0,002 and p=0,001, respectively). The VA severity decreased significantly after BB (147 (37.9%) (non-sustained) ventricular tachycardia ((NS)VT) and 120 (30.9%) no or isolated ventricular premature beat (iVPB) pre-EST vs 46 (11.4%) (NS)VT and 184 (45.7%) iVPB post-EST, p<0,001). Examining the different groups, the VA severity decreased significantly after BB in all but atenolol (13 (40.6%) (NS)VT and 8 (25.0%) iVPB pre-EST vs 9 (25.0%) (NS)VT and 15 (41.7%) iVPB post-EST, p=0,103).

Based on these results we conclude that all beta-blockers except atenolol are effective in reducing the VA severity on EST in patients with CPVT.

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): E-Rare Joint Transnational Call for Proposals 2015 “Improving Diagnosis and Treatment of Catecholaminergic Polymorphic Ventricular Tachycardia: Integrating Clinical and Basic Science”

Exercise and the multidisciplinary holistic approach to adolescent dysautonomia

AIM

To determine whether an eight-week strength training programme as part of a multidisciplinary approach would minimise symptoms and improve quality of life in patients with dysautonomia.

METHODS

Adolescents referred to a tertiary-level cardiology service from May 2014-December 2015 with symptoms of dysautonomia were eligible. Participants completed an exercise test and a quality of life (QoL) questionnaire (PedsQL) prior to the intervention. Participants were asked to complete exercises five times per week. After eight weeks, participants returned for follow-up testing. Parents completed a proxy report of their child's QoL at both time points.

RESULTS

A total of 17 participants completed the study protocol with an adherence rate of up to 50%. Post-intervention, QoL scores improved across all levels in the participants [total 65.2 (50.4-74.7) vs 48.9 (37.5-63.0); p = 0.006; psychosocial 65.8 (56.1-74.6) vs 50.0 (41.7-65.8); p = 0.010; physical 62.5 (37.5-76.6) vs 43.8 (25-68.5); p = 0.007] and their parent proxy reports [total 63.5 (48.7-81.3) vs 50.0 (39.3-63.0); p = 0.004; psychosocial 62.1 (52.1-81.3) vs 50.0 (39.6-59.2); p = 0.001; physical 62.5 (51.6-80.0) vs 50.0 (27.5-70.3); p = 0.003]. Treadmill time also improved (9.1 vs 8.0 minutes; p = 0.005).

CONCLUSION

Following an eight-week strength training programme, dysautonomia patients report a significant improvement in both their quality of life and endurance time.