When using the bell of the stethoscope and recording over the apex of the heart, the extra sound heard on auscultation is most consistent with an S4 gallop. S4 gallops usually occur late in diastole and are thought to be caused by the atria contracting against a non-compliant left ventricle. In this patient, this was one of many signs confirming the diagnosis of heart failure with reduced ejection fraction (HFrEF). Learn more at https://www.ekohealth.com/blogs/education