Helix-fixation atrial leadless pacing for rhythm-mediated cardiogenic shock after acute myocardial infarction.

Cardiogenic shock complicating inferior acute myocardial infarction is usually attributed to pump failure, but rhythm-mediated mechanisms may predominate when ischemia involving the sinoatrial nodal artery produces sinus node dysfunction, chronotropic incompetence, and junctional rhythm-induced atrioventricular dyssynchrony. We report a 79-year-old man who developed recurrent cardiogenic shock several hours after successful revascularization for inferior ST-elevation myocardial infarction despite only mildly reduced left ventricular systolic function. Invasive hemodynamic assessment demonstrated that increasing the temporary right ventricular pacing rate failed to improve left ventricular systolic pressure, whereas right atrial appendage pacing immediately restored hemodynamics, establishing chronotropic incompetence and loss of atrioventricular synchrony as the dominant contributors. Because durable atrial pacing was required and prolonged temporary atrial pacing was impractical, a helix-fixation atrial leadless pacemaker was implanted despite markedly adverse acute ischemic atrial electrical parameters, including blunted local electrograms, minimal current of injury, and a high initial pacing threshold. Pacing thresholds improved progressively after implantation, and hemodynamic stability was maintained without escalation to advanced mechanical circulatory support. To our knowledge, this is the first reported use of atrial leadless pacing in the acute phase of myocardial infarction.