The Disappearing Murmur: Systolic Anterior Motion of the Mitral Valve Leaflet in a Non-hypertrophic Cardiomyopathy Patient

Transient Systolic Anterior Motion of the Anterior Mitral Valve Leaflet in a Critical Care Patient with a Structurally Normal Heart

Systolic anterior motion (SAM) is defined as the displacement of the anterior mitral leaflet towards the left ventricular outflow tract, which results in left ventricular outflow tract obstruction (LVOTO). The SAM of the anterior mitral leaflet is a well-established phenomenon in hypertrophic obstructive cardiomyopathy (HOCM), but its occurrence in a structurally healthy heart is uncommon. We present a critical care patient with presumed septic shock whose blood pressure was previously controlled by fluid resuscitation and vasopressors. He developed a new cardiac murmur along with hypotension despite being on vasopressors. The echocardiographic assessment revealed no structural heart disease or valvular vegetations but a hyperdynamic left ventricle with significant SAM of the anterior mitral leaflet, resulting in mitral regurgitation (MR). The murmur and hypovolemia resolved after aggressive fluid resuscitation and by decreasing the vasopressor dose.