SNOWMASS, COLO. – The relentless national emphasis on reducing door-to-balloon times for ST-elevation myocardial infarction patients at percutaneous coronary intervention centers may have gotten out of hand, Dr. Bernard J. Gersh asserted at the annual cardiovascular conference at Snowmass sponsored by the American College of Cardiology.
"It’s very difficult for me to stand up here and preach longer door-to-balloon times. It’s an un-American act, really. But I do think we’re getting door-to-balloon times so short that we’re starting to miss the big picture. We’re going to have to rethink this and not be penalized because we divert the patient to the coronary care unit just for 15 minutes to talk to the patient and try to answer some questions," said Dr. Gersh, professor of medicine at the Mayo Clinic, Rochester, Minn.
Average door-to-balloon times (DBTs) at percutaneous coronary intervention (PCI) centers have dropped substantially over the past decade. And DBT is a useful surrogate for overall care. But further reductions in DBT are not going to improve mortality. Moreover, they’ll have adverse consequences in terms of patient safety and health care costs, according to the cardiologist.
Dr. Gersh and his colleagues showed in a secondary analysis of 4,548 STEMI patients in the HORIZONS-AMI and CADILLAC trials that short DBTs of 90 minutes or less were associated with significantly lower 1-year mortality in subjects presenting to PCI centers within the first 90 minutes of ischemia, but had less impact for patients presenting with longer ischemia times (J. Am. Coll. Cardiol. 2010;56:407-13). And most patients in real-world clinical practice, as in these two trials, do present later.
"As we look to the future for further improvements in STEMI outcome, the focus is going to be outside the PCI hospital. It probably won’t be on new stents or new drugs. Transfer times are going to be a target. We’ll need coordinated reperfusion networks and development of protocols, and communication delays will have to be looked at," he said.
Another key strategy in improving STEMI outcomes will require shortening the time from symptom onset to first medical contact through greater public awareness and willingness to seek help quickly. That’s far easier said than done. "This is the most difficult part. This has been the Achilles heel of reperfusion therapy, and nothing really has worked to date," Dr. Gersh noted.
The counterproductive repercussions of pushing for faster and faster DBTs are illustrated by a report on 1,335 patients with suspected STEMI transferred to the Minneapolis Heart Institute for possible primary PCI from 30 outside hospitals in a regional network. At coronary angiography, 14% had no culprit lesion and 9.5% had no significant coronary artery disease. Among the subgroup of patients with left bundle branch block, these figures were threefold greater (JAMA 2007;298:2754-60).
More recent studies suggest false-activation cardiac catheterization laboratory rates may be even higher than in the Minneapolis report. For example, among 411 consecutive patients referred for primary PCI for suspected STEMI after presenting to the emergency departments at two Boston-area primary PCI-capable hospitals, 36% were found to not actually have STEMI (Arch. Intern. Med. 2012;172:864-71).
"There is merit in taking perhaps 10 minutes to just examine the patient before we put them on the catheterization table," Dr. Gersh observed. "Do they have pericarditis? Is this an aortic dissection? Is there intracranial pathology? Do they have a pacemaker? Is this an MI or is it really noncardiac pain?"
The other unwanted fallout from rushing to minimize DBTs is that all too often cardiologists are implanting drug-eluting stents without knowing whether a patient is capable of complying with the requirement of 12 months of dual antiplatelet therapy or can afford it. Furthermore, cardiologists don’t know what the renal function is, or whether the patient plans to have noncardiac surgery, which becomes more vexing in the setting of dual antiplatelet therapy.
Dr. Gersh believes the way forward in achieving further improvement in STEMI outcomes requires greater emphasis upon DIDO, or door-in to door-out time, defined as the time interval between patient arrival to discharge at the first or referring hospital. This is now a Centers for Medicare and Medicaid Services–mandated performance measure, with a recommended DIDO time of 30 minutes or less.
"This is a very good metric because it shares accountability. It puts the onus on the hospital transferring the patient, not just the referral center. It emphasizes a joint responsibility involving what they do at the receiving hospital and what we do at the primary PCI center," he explained.
The most recent report from the National Cardiovascular Data Registry’s ACTION Registry–Get With the Guidelines database underscores the enormous room for improvement in DIDO times. In a review of nearly 15,000 STEMI patients transferred for primary PCI to 298 referral centers, the median DIDO time was 68 minutes. Only 11% of patients met the recommended DIDO benchmark of 30 minutes or less. In-hospital mortality in those patients was 2.7%, compared with 5.9% in those with DIDOs greater than 30 minutes, a highly significant difference (JAMA 2011;305:2540-7).