According to another media report:
""The evidence at trial showed, and the jury found, that for at least two patients in 2004, Natale prepared false post-operation reports that, among other things, contained extensive details about aneurysm repairs that he never performed, and falsely described the surgeries he did perform as being more complex and elaborate than they actually were. In the case of one patient whose medical condition deteriorated a year after Natale operated, another surgeon testified that he had to untangle the falsehoods in Natale's records, which, if relied upon, would have had a serious impact on his subsequent treatment of that patient."
It is likely that last sentence that "killed" him...