Sample ECG recordings from the exercise stress tests in the Group A and B. A 33-year-old male patient from Group A reported exercise-induced syncope since the age of 14. Resting ECG was normal except for a relative bradycardia of 45 bpm (1). After the threshold heart rate of 128 bpm, the exercise stress test revealed polymorphic VPCs typical of CPVT (2) that disappeared in the recovery phase (3). Three of the 16 examined individuals in the family had a similar phenotype and carried the RyR2 exon 3 deletion. The 57-year-old female patient in Group B showed frequent VPCs in baseline ECG (4), in the exercise stress test (5) and in the recovery phase (6). A total of 13 patients of the 77 clinically evaluated subjects in the family featured a similar atypical phenotype. No disease-causing variants were detectable in the screened genes.