LAUSR

Given the characteristics of the physical activity during childhood, high-intensity exercise test protocols may better represent the cardiovascular conditions that trigger symptoms. Introduction Exercise stress tests are commonly used to evaluate symptoms, such as palpitations, that occur during exercise. The most commonly used exercise stress test in both children and adults is a graded exercise test (GXT) that starts at a slow pace and increases the speed and incline in a stepwise fashion. However, a GXT does not often accurately reproduce the cardiovascular conditions that result in symptoms, particularly in children and young athletes. A high-intensity exercise test (HIXT) protocol that consists of short durations at higher speedsmaymore accurately simulate the cardiovascular conditions likely to elicit patient symptoms. Herein, we present 2 cases in which a HIXT led to the diagnosis of exercise-related arrhythmias, previously unrecognized by GXT. High-intensity exercise test protocols may lead to a higher catecholaminergic state. This is why a repetitive sprint-based high-intensity protocol, tailored to the physical training level of the patient, may be more suitable than graded tests in the attempt to reproduce arrhythmias in patients with exercise-related symptoms. Case report Case 1 A previously healthy 12-year-old female subject with no significant past medical history and no concerning family history was seeking cardiac clearance to participate in competitive sports after premature ventricular contractions (1% of total beats) and 1 asymptomatic 4-beat run of monomorphic ventricular tachycardia (VT) at a rate of 185 beats per minute (BPM) were seen on an ambulatory electrocardiogram (ECG) monitor (Figure 1a). After a normal echocardiogram and a resting ECG showing sinus bradycardia at 46 BPM, a GXT utilizing an institutional accelerated Naughton protocol (2 metabolic equivalent increments every 2 minutes) was performed. This showed a limited peak oxygen uptake (VO2 max was 64% of predicted) and limited heart rate response (maximal heart rate 148 BPM, 74% of predicted)