We previously reported that patients undergoing interhospital transfer for primary percutaneous coronary intervention (PCI) in the U.S. rarely met national guidelines-based recommendations of door-to-balloon times of ≤90 min using data from 1999 to 2002 in the National Registry of Myocardial Infarction (NRMI) (1). The median “total” door-to-balloon time, that is, the time from arrival at the first hospital to initial balloon inflation at the PCI hospital, in these patients was 180 min and only 4.2% had times <90 min. Since the publication of that report, there have been widespread efforts to improve timely access to primary PCI through the establishment of regionalized networks of hospitals for ST-segment elevation myocardial infarction (STEMI) (2- 3). However, more contemporary data on total door-to-balloon times in patients undergoing interhospital transfer for primary PCI have yet to be reported.

We used 2005 and 2006 data from the American College of Cardiology National Cardiovascular Data Registry's CathPCI registry. Details of hospitals and data collection methods used by the National Cardiovascular Data Registry have been previously described (4). We included all catheterization laboratory visits of STEMI patients undergoing primary PCI after interhospital transfer (n = 22,019). To narrow our study population further, we excluded catheterization laboratory visits by patients: 1) who presented to the hospital more than 12 h after symptom onset (n = 2,993) or with uncertain time of symptom onset (n = 453); 2) who received any fibrinolytic therapy before arrival in the cardiac catheterization laboratory (n = 2,622); 3) with unknown or invalid date/time of reference for hospital arrival or PCI (n = 852); 4) with door-to-balloon times >12 h (n = 1,677); and 5) with any combination of the above exclusions (n = 6,874). This restricted our study population to 15,145 catheterization laboratory visits in 15,049 patients at 491 hospitals.

Our primary end point was “total” door-to-balloon time, which was defined as the time of arrival at the first hospital to the time of initial balloon inflation at the PCI hospital. We also evaluated: 1) door-to-door time (time of arrival at the initial hospital to time of arrival at the PCI hospital); and 2) PCI hospital door-to-balloon time (time of arrival at the PCI hospital to time of the first balloon inflation at the PCI hospital). Univariable analyses were used to report characteristics of the study population and the distribution of these end points.

The mean age of the study population was 60.5 years; 29.0% were women, 88.3% were white, and 20.8% had diabetes mellitus. In addition, 31.6% of patients arrived at the first hospital on weekdays between 8 am and 4 pm, 14.6% presented >6 h after symptom onset, and 10.6% were in cardiogenic shock. The median time from arrival in the initial hospital to the first balloon inflation time at the PCI hospital (i.e., total door-to-balloon time) was 152 min (interquartile range 116 to 211 min). Total door-to-balloon time was <2 h in 27.7% of patients, between 2 and 4 h in 53.9% of patients, and ≥4 h in 18.4% of patients (Figure 1). Only 8.6% of patients had total door-to-balloon times <90 min. The median door-to-door and PCI hospital door-to-balloon times were 109 and 38 min, respectively.

The use of primary PCI in patients with STEMI is rising in the U.S. (5). However, there continue to be concerns about its effectiveness in patients undergoing interhospital transfer, given the potential risks of delays in time-to-reperfusion. Although we previously reported that such delays are common, those results used data collected before the publication of the DANAMI-2 (Danish Multicenter Randomized Study on Thrombolytic Therapy Versus Acute Coronary Angioplasty in Acute Myocardial Infarction-2) trial (6). This landmark study, which found that interhospital transfer for primary PCI is both feasible and efficacious within the controlled setting of a clinical trial, has prompted local and national efforts in the U.S. to improve timely access to primary PCI by establishing regionalized networks of hospitals for STEMI.

In this context, the present analysis adds important new information to the literature. Our findings suggest shorter total door-to-balloon times in transfer patients during the intervening few years (i.e., 152 min vs. 180 min). However, we also found that many patients still have marked delays in total door-to-balloon times and that few reach the benchmark established by national guidelines. Compared with the previous analysis, total door-to-balloon times were shorter because of more rapid door-to-door times (109 min vs. 120 min) and PCI hospital door-to-balloon times (38 min vs. 53 min). Of course, any direct comparisons between the present and previous analyses should be done with caution, owing to the involvement of different hospitals and types of patients between registries. The present analysis, for example, included more nonurban hospitals as well as patients with cardiogenic shock. Finally, it is important to note that these hospitals participated voluntarily in the CathPCI registry, a national quality improvement registry. These hospitals therefore may present a “best”-case scenario for transfer patients.