Author + information
- Ali E. Denktas, MD⁎ (, )
- H.V. Anderson, MD,
- James J. McCarthy, MD and
- Richard W. Smalling, MD, PhD
- ↵⁎Division of Cardiovascular Medicine, Department of Internal Medicine, University of Texas Medical School and, Memorial Hermann Heart and Vascular Institute, 6431 Fannin, MSB 1.246, Houston, Texas 77030
We appreciate the comments of Dr. Conti on our paper (1). We agree with Dr. Conti that the door-to-balloon (DTB) time is a well-established and well-studied measure in myocardial infarction. It is our opinion, however, that this measure fails to take into account the period before the patients present to the hospital. We also seem to have reached a plateau in terms of getting any further benefit by additional shortening of the DTB time. As reported by Flynn et al. (2), the DTB has declined in Michigan each year, from 113 minutes in 2003 to 76 min in 2008, but the mortality rate failed to follow this decrease. The in-hospital mortality was 4.1% in 2003 and 3.62% in 2008 (p = 0.69). Similarly, in 43,678 patients with acute myocardial infarction in the United States evaluated from 2005 to 2007, although the DTB time decreased from 101 to 87 min, the mortality did not change (3). Indeed, as stated in our paper, the true window for infarct salvage is ideally less that 2 h of ischemic time. Typically, the “door time” in much of the world is well beyond 2 h after start of symptoms, which explains why there is little-to-no correlation with improvements in DTB time and improvements in mortality.
Dr. Conti states that it is difficult to determine the onset of symptoms. We would suggest that although this is true of some patients, many patients are able to accurately report when their symptoms started. When DTB first began to be tracked, certain changes in data collection were made, such as arrival times and departure times, which then required efforts to synchronize clocks in emergency departments and catheterization laboratories, and so forth: efforts that are still incomplete. When and if we start tracking the true ischemic times, emergency responders and physicians will become more alert to the symptom onset as a valuable time to record. Thus, the estimation of the true ischemic time will become easier.
The factors suggested by Dr. Conti that influence the outcome of the patients with ST-segment myocardial infarction are all valid. Unfortunately, they are not adequately addressed in the trials where influence of DTB time on outcomes has been studied.
Our goal in treating myocardial infarction should be both to decrease mortality and preserve left ventricular function (prevent the development of heart failure). Because the time from symptom onset to reperfusion has been shown to decrease infarct size, it is only natural now to target it as representative of the total ischemic time. We should start measuring it routinely.
- American College of Cardiology Foundation