Review Question - QID 109037

A 78-year-old man arrives at the emergency department after slipping on the ice while shoveling snow. He denies palpitations, diaphoresis, or chest pain. He did not lose consciousness or hit his head during the fall. His past medical history is notable for poorly controlled hypertension and an asymptomatic left bundle branch block. His temperature is 99.1°F (37.3°C), blood pressure is 168/86 mmHg, pulse is 85/min, respirations are 18/min, and oxygen saturation 99% on room air. Physical exam shows no peripheral edema and lungs clear to auscultation. An EKG is performed in the emergency department and is shown in Figure A. Echocardiogram shows no valvular abnormalities with an ejection fraction of 55%. Troponin-I for this patient is 0.01 ug/L. On cardiac exam, an extra heart sound is auscultated. During which phase of the cardiac cycle would this sound most likely appear based on this patient’s history and EKG?