All the above loud S1 caused by

Ref Harrison 19 th ed pg 1447 The intensity of S1 is determined by the distance over which the ante- rior leaflet of the mitral valve must travel to return to its annular plane, leaflet mobility, left ventricular contractility, and the PR interval. S1 is classically loud in the early phases of rheumatic mitral stenosis (MS) and in patients with hyperkinetic circulatory states or sho PR inter- vals