An early systolic murmur may be caused by all of the following except -

Early systolic murmurs begin with S 1 and extend for a variableperiod, ending well before S 2 . Their causes are relatively few innumber. Acute, severe MR into a normal-sized, relatively noncompliantleft atrium results in an early, decrescendo systolic murmurbest heard at or just medial to the apical impulse. Tricuspid regurgitation (TR) with normal pulmonary aerypressures, as may occur with infective endocarditis, may producean early systolic murmur. The murmur is soft (grade 1 or 2), is bestheard at the lower left sternal border, and may increase in intensitywith inspiration (Carvallo's sign). Regurgitant " c - v " waves may bevisible in the jugular venous pulse. TR in this setting is not associatedwith signs of right hea failure. Harrison's principle of internal medicine,20edition,pg no.1532