Additional Contributions: The following Michigan physicians and hospitals contributed data to this study: Cyril Ruwende, MD, David Williamson, MD, and Paul Corcoran, MD, Allegiance Health, Jackson; Eugene Laveroni, DO, Scott G. Jennings, DO, and David Fertel, DO, Botsford Hospital, Farmington Hills; Jeffrey Rubin, MD, and Theodore Schrieber, MD, Harper Hutzel Hospital, Detroit; Adam Greenbaum, MD, Timothy Nypaver, MD, and Todd Getzen, MD, Henry Ford Hospital, Detroit; Richard McNamara, MD, Dennis Dunning, MD, M. Ashraf Mansour, MD, and Michael Knox, MD, Meijer Heart Center, Grand Rapids; James Fox, MD, William Ranger, MD, Roberto Corpus, MD, and Michelle Lung, MD, Munson Medical Center, Traverse City; Arthur Riba, MD, Thomas Siegel, MD, Brent Thompson, MD, and S. Yellayi, MD, Oakwood Healthcare System, Dearborn; William Oppatt, MD, Providence Hospital, Southfield; Milind Karve, MD, and Ara Pridjian, MD, Sparrow Hospital, Lansing; Thomas Davis, MD, St John Hospital, Detroit; Charles Nino, MD, and David Schulman, MD, St John Hospital Macomb-Oakland, Warren; Herb Aronow, MD, MPH, Art Szyniszewski, MD, Vishal Bhagat, MD, Walter Whitehouse, MD, and Brian Halloran, MD, St Joseph Mercy Hospital Ann Arbor, Ypsilanti; P. Michael Grossman, MD, Stanley Chetcuit, MD, David Williams, MD, and Jon Eliason, MD, University of Michigan Health System, Ann Arbor; P. Michael Grossman, MD, Peter Henke, MD, and Venkat Krishnamurthy, MD, Veterans Affairs Medical Center Ann Arbor; Paul Bove, MD, Steven Wang, MD, and Terry Bowers, MD, William Beaumont Hospital Royal Oak, Royal Oak; Steven Rimar, MD, Mark Friedland, MD, Michael Bischoff, MD, and Terry Bowers, MD, William Beaumont Hospital Troy, Troy; and Musafa Hashem, MD, Henry Ford Wyandotte Hospital, Wyandotte.