Watch the Riverside: Rhythm 1 online guitar lesson by Andy Aledort from Jam Night Vol. 1
In this example, I simply switch back and forth between one bar of Em, or Em7 or Em9, and A7. While playing the A7 chord, I often also incorporate A7sus4. Keep in mind that the suspended fourth of A is D, which is also the dominant seventh of E minor. For each chord, the open-string root note is sounded on beat one of each successive bar, followed by similar syncopated strumming pattterns, basically utilizing a down-up-down motion that emphasizes shifting 16th-note rhythms. Notice the incorporation of Em9 in the second half of the example.