June 23rd, 2011
The Elusive 30-Minute “Door-In to Door-Out” Benchmark for Primary PCI Transfers
The editors at CardioExchange have again asked a panel of experts to respond to a clinically important study. This time it was a retrospective cohort study, published in JAMA, of door-in to door-out (DIDO) times for patients with ST-segment-elevation MI who had been admitted to one hospital and then were transferred to another center for primary PCI.
Few of the nearly 15,000 transferred patients had a DIDO time of 30 minutes or less, but that short transfer time was associated with shorter reperfusion delays and lower in-hospital mortality than was a DIDO time >30 minutes. (See the CardioExchange news story on the study.)
We put two questions to four experts, including the lead author of the study. Here are their responses:
How should front-line clinicians respond to the finding that a DIDO ≤30 minutes had clear time-to-reperfusion and outcome advantages but that very few transferred patients actually met that time threshold?
Tracy Wang (lead study author, Duke): These results are surprising given the tremendous focus on reducing reperfusion delays for STEMI patients in recent years. What’s even more surprising is that a substantial proportion of STEMI patients intended for primary PCI have DIDO times >90 minutes, rendering the guideline-recommended overall door-to-balloon time of ≤90 minutes impossible. Some of this may perhaps be explained by the fact that sicker patients may need more stabilization before transfer, but it certainly doesn’t explain the large majority of transferred STEMI patients with prolonged DIDO times. The results underscore the need to prospectively establish STEMI systems of care that facilitate communication and minimize redundancy to expedite transfer between STEMI referral and receiving centers.
Timothy Henry (U. Minnesota): This article illustrates the importance of the DIDO time as a key component of the total door-to-balloon time. Regional STEMI systems should focus on the components of this delay and implement changes to shorten it. Still, based on a wealth of data, the overall door-to-balloon time remains the factor critical in our decision regarding the choice of reperfusion. Data from our regional STEMI system, currently under review, indicates the specific reason for the delay may be as important as the length of the delay itself.
Ivan Rokos (UCLA): From my emergency medicine perspective, the slow DIDO times at STEMI referral facilities do not surprise me. I believe the cause is multifactorial, most commonly due to bad systems rather than bad EM doctors and nurses. Most important, current literature demonstrates that having a prearranged plan between referral and receiving hospitals is critical, but it is often lacking in the real world. Multiple other key steps affect DIDO at the referral facility, including door-to-ECG, ECG-to-diagnosis, diagnosis to acceptance by the receiving hospital (an EMTALA requirement), acceptance to activation of transport, activation to arrival of transport vehicle, and transport team arrival to departure.
Jeptha Curtis (Yale): Clinicians need to critically examine the outcomes achieved at their own institutions. At a national level, these findings are a clear signal (one of many) that these patients are falling between the cracks. We have made such amazing strides with door to balloon times among patients who arrive at a PCI capable facility, but we have made little if any real progress with this vulnerable population. After reviewing their outcomes (which are likely to be equally dismal), clinicians at both sending and receiving hospitals need to get engaged- creating working groups, maintaining communication between hospitals, and convincing leadership to make the capital and personnel investments needed to improve.
If patients cannot be transferred out within 30 minutes, should those eligible for lytic therapy receive it?
Tracy Wang (lead study author): Absolute contraindications to fibrinolysis were found to occur rarely in the transferred STEMI population. Therefore, if DIDO time is anticipated to exceed 30 minutes, fibrinolysis should be considered among eligible patients depending on symptoms and bleeding risk.
Timothy Henry: See Dr. Henry’s comment above.
Ivan Rokos: It depends on the setting (urban/suburban vs. rural/remote) because transport time (related to geography, weather, road conditions) also affects overall reperfusion time. Literature supports a pharmaco-invasive strategy for long-distance transfers >60 miles. For shorter transfers, transfer-PCI should generally be the goal. In Los Angeles County, our published data support transfer via 9-1-1 providers, who arrive at the receiving hospital ED with the same urgency as at any other “prehospital scene.” I am an optimist and believe that we can improve interhospital transfer by creating systems and networks that are supported by quality-improvement registries and benchmarks. The DIDO ≤30 minutes metric will, I hope, have the same national impact on improving interhospital transfer as D2B had on primary PCI for patients who present directly (via paramedic or self-transport) to a receiving hospital.
Jeptha Curtis: The easy answer is that every patient is different and needs to be assessed on a case-by-case basis. Yes, there will be situations where lytics should be given, but the question is not at the level of the individual patient, but rather is a function of what the system can reliably achieve. The reality is that clinicians and hospitals do much better when they pick a strategy and stick with it. I suspect adding a lytic arm to the decision matrix would only confuse matters and increase delays. Instead, hospitals that commit to a transfer strategy need to focus their efforts on reducing delays. However, they need to be willing to revisit that decision if they cannot get at least half of their patients out the door within 30 minutes.
How would you answer the two questions we put to our experts? And what do you think of their answers?