Primary percutaneous coronary intervention expansion to hospitals without on-site cardiac surgery in Michigan: a geographic information systems analysis.

Background: In 2005, Michigan expanded primary percutaneous coronary intervention (P-PCI) capability to 12 hospitals without on-site cardiac surgery. We determined the potential impact of this expansion on geographic access to P-PCI for patients.

Methods: Geographic information systems using the US Census Survey and hospital data from the state of Michigan were used to construct maps with 20-mile hospital service areas around P-PCI hospitals with and without on-site cardiac surgery. Geographic access was calculated as the percentage of the population living within the hospital service areas of these 2 types of hospitals.

Results: Of 9,938,444 persons in Michigan, 7,694,834 (77.4%) lived within 20 miles of a P-PCI hospital. Thirty centers with on-site cardiac surgery provided access for 7,219,995 persons (72.6%). The 12 P-PCI hospitals without on-site cardiac surgery increased access by 474,839 persons (4.8%). Of these, 3 geographically isolated facilities, which were at least 20 miles away from another P-PCI hospital, accounted for the greatest improvement in geographic access (n = 425,700 [4.3%]), whereas the remaining 9 hospitals increased access by only 49,139 persons (0.5%).

Conclusions: Expansion of P-PCI to hospitals without on-site cardiac surgery in Michigan improved geographic access to a modest extent.