The correct solution is number 4. Palpitations and exercise-induced presyncopal sensation, along with frequent ventricular extrasystoles and repolarization changes in the right precordial leads, is a strong indicator of arrhythmogenic cardiomyopathy. Gadolinium uptake in the right ventricular free wall is associated with a particularly serious condition and risk of sudden cardiac death.1 Progressive onset of tachycardia is observed during exercise with a sharp decrease in cycle length once tachycardia becomes established (response 1, incorrect). Tachycardia presents with pleomorphism and, after several beats, becomes regular (response 2, incorrect). Finally, the cycle length (260-270ms) is not typical of atrial flutter (response 3, incorrect). Genetic testing was performed. Heterozygous PKP2 mutation, which is typical of arrhythmogenic cardiomyopathy, was detected. A dual-chamber defibrillator was implanted,2 and treatment initiated with sotalol. Genetic screening of family members was performed and exercise was contraindicated.