P mitrale is broad, notched P waves in several or many leads with a prominent late negative component to the P wave in lead V1, and may be seen in MI, but also in mitral stenosis, and, potentially, any cause of overload of the left atrium [REF].
regurgitant fraction = \frac{V_{mitral} - V_{aortic}} {V_{mitral}} \times 100\% .