Complex sentence: The third form, which is recognized much less frequently, is characterized by myocardial systolic dysfunction, which may result in left-sided, right-sided, or bi-ventricular congestive heart failure.
Split into simpler sentences: The third form, which is recognized much less frequently, is characterized by myocardial systolic dysfunction. This may result in left-sided, right-sided, or bi-ventricular congestive heart failure.