1 Department of Medicine, University of Alabama at Birmingham (UAB); Birmingham, AL, USA; Division of Cardiovascular Diseases, UAB Department of Medicine; Birmingham, AL, USA; UAB Comprehensive Cardiovascular Center; Birmingham, AL, USA; Birmingham VA Health Care Center; Birmingham, AL, USA.
2 Department of Medicine, University of Alabama at Birmingham (UAB); Birmingham, AL, USA; Division of Cardiovascular Diseases, UAB Department of Medicine; Birmingham, AL, USA; UAB Comprehensive Cardiovascular Center; Birmingham, AL, USA; Birmingham VA Health Care Center; Birmingham, AL, USA; UAB Cardiopulmonary Research Program; Birmingham, AL, USA. Electronic address: gpayne@uabmc.edu.