[Basics in the EP lab-how and when to pace?]

Electrical stimulation is a central tool in the evaluation and management of arrhythmias in the electrophysiological laboratory. Targeted atrial and ventricular pacing maneuvers allow induction, mechanistic characterization, and termination of arrhythmias. This provides important insights into the involved conduction pathways, anatomical location, and the underlying arrhythmogenic substrate, thereby forming the basis for a tailored ablation strategy. A structured approach even prior to the first stimulation maneuver establishes the foundation for successful diagnosis and therapy (ensuring stable catheter positions, optimal signal quality, and reliable capture). Understanding fundamental principles such as incremental, programmed, burst and overdrive stimulation is essential for accurate interpretation of electrophysiological responses. The consolidation of knowledge over the past three decades has helped ensure that, today, a few key maneuvers are usually sufficient to enable a rapid and reliable diagnosis. These play a key role in differentiating regular narrow-complex tachycardias, distinguishing wide-complex tachycardias, and identifying reentrant vs. nonreentrant mechanisms. They are also indispensable for assessing procedural endpoints after ablation, including confirmation of noninducibility of the clinical tachycardia or successful pulmonary vein isolation. The present review further outlines practical solutions to common challenges such as inconsistent pacing responses, far-field signals, and nonreproducible arrhythmia induction. Overall, systematic application of pacing maneuvers enables precise mechanistic classification of tachycardias and significantly contributes to safe, efficient, and individualized electrophysiological therapy.