Conversations in Cardiology: Door-to-Balloon Time

A question was posed to me last week: "Without an on-site, on-call interventionalist and lab team, there is a limit to how low the Door-toBalloon (D2B) time can go before someone gets killed trying to get to the hospital to meet an arbitrary time frame. Is there a statistically significant difference in mortality, CHF, structural heart complications (VSD, MR, cardiac rupture, etc) or life-threatening arrhythmias if the median D2B is 49 minutes vs 70 minutes? "

A quick thumbs up or down on whether forced reduction of DTB is

1. benefical for the patient - or -
2. the hospital - or -
3. the interventionalist and if you have time, a short rationale.

My view: No measurable individual hospital mortality difference between 90-70min. No sure about less than 50min, but we could never achieve this number no matter what we did unless doctors and nurses lived in the hospital. So my answer to 1, 2, and 3 above is no, no, and no. Let me know what you think and we'll share it.

Morton J. Kern, MD
University of California Irvine

1. yes*, 2. no, 3. yes/no

1) The problem is the door to balloon time doesn't tell you the "myocardial ischemic time", which is what really matters. DTB is merely a surrogate. Certainly, the shorter the ischemic time, the better for the patient.

2) Forcing very short DTB will cost money as teams will have to stay in the hospital which is a loser for the hospital.

3) Depending on the individual interventionalist's status, the extra-on call money to stay in the hospital could be good for him/her, but for a more mature individual, the comfort of sleeping in their own bed may be more valued.

4) Therapeutic hypothermia will be a game changer. STEMI's will be placed in hibernation and brought out of the freezer each morning for "elective PCI".

Christopher J. White, MD
Ochsner Heart and Vascular Institute

There has been no change in mortality since the D2B has almost been halved. That has been published from Michigan and now the data from NCDR supports that

David R. Holmes, Jr, MD
Mayo Clinic

Mortality reduction is a continuous function. The rise in mortality is trivial between 70-90 min. The goal is to save lives for the patient and preserve lives of the operators!

Barry F. Uretsky, MD
University of Arkansas for Medical Sciences, Little Rock

Well, about half the studies show no reduction in mortality, and about a half show, or suggest, a reduction in mortality - including this one from you. I don't know any that showed an increase in mortality.

Peter B. Berger, MD
Geisinger Center for Clinical Studies

Mort - some general observation.

No study has suggested that having a whole interventional team in-house lowers mortality.

If the interventional MD drives at break-neck speed and has an accident, the DBT will be really, really long. So a measured response is the most appropriate.

E. Magnus Ohlman, MD
Duke University Medical Center

See Rathorne, BMJ 2009;338:1807. No recent studies showing further mortality reduction by shaving a few more minutes after the gains made with the initial interventions. NCDR analysis in press: no mortality reduction with 15 minute time reduction over 3 years. Note the difference between the association between ischemic time and mortality and the association between changing time and changing mortality rates. The same conundrum exists for high on-treatment platelet reactivity.

Eric R. Bates, MD
University of Michigan Medical Center

Great questions. As we shorten the DTBs we are doing so by relinquishing the interaction of those most experienced in the management of ACS, ie Interventional Cardiologists, to those least experienced, ie EMS and ED MDs. The potential benefit is an improvement in outcomes, yet to be proven; the downside is an increase in inappropriate activation of health care resources for possible STEMI. At least in our system, activation of the cath lab inappropriately is higher than comfortable and on a trajectory that is stretching cath lab resources thin.

Robert J. Applegate, MD
Wake Forest University School of Medicine

Mort,

You asked for a "quick" thumbs up/thumbs down but as you can see, the issues are complex!

My understanding is that many hospitals are now requiring 60 minute D2B (like in the city of Miami), and while we can all agree that rapid treatment is important, I am not sure that reducing it way below 90 minutes at the expense of safety - operator, cath lab staff, and patient - is a good thing.

The fundamental problem is that we are mandated to reduce a surrogate endpoint, namely D2B, rather than reduce mortality, which should be the goal. So many hospitals have complied by improving care processes and maybe also by "refining" the denominator. That is, by dropping out the sickest patients. What you end up with is low risk patients getting super fast door-to-balloon times. I once heard an interventionalist say "well, if they're going to measure door-to-balloon times, I'll just deploy the balloon on the table," which of course misses the point.

It reminds me of the likely apocryphal story of a post-WW II Eastern bloc country where the communist government realized that the annual production of tractors in the government-owned factory had dropped by 200 tons. So they mandated that the production of tractors increase by 200 tons the following year. Sure enough, the factory met that goal. The problem was that they didn't make any more tractors; they just made each tractor heavier.

To answer your query directly: 1) Yes; 2) Yes (CMS "forces" hospitals to reduce D2B, and those with supershort times advertise this on billboards); 3) Maybe (in some centers, operators that consistently have long D2B get less cath lab time).

Sunil V. Rao, MD
Duke University Medical Center

Numerous large-scale observational studies have shown a relationship between DBT (and total time from symptom onset to balloon) on mortality. And yes, now that we have shaved more than 30 minutes off our national DBT, several studies are showing no effect of this on decreasing mortality (Arch Intern Med. 2009;169:1411-1419, Arch Intern Med. 2010;170:1842-1849, NCDR, etc.). How can you rationalize these disparate findings? First is the issue of confounders. In large registry studies, which pts have long DBTs? This isn’t a chance occurrence. Long DBTs occur in pts who are most ill (requiring medical stabilization), such as pulmonary edema, hypotension, arrhythmias, confusion unable to provide consent, etc. Of course their mortality will be higher, and the most sophisticated multivariable analysis cannot adequately control for all these variables. Second, studies by our group, Brodie and others have repeatedly shown that the relationship with DBT and mortality is only present in high-risk pts with a large amount of myocardium at risk (e.g. anterior MI), and those presenting early in whom the myocardium is still viable (i.e. within 1-2 hrs of symptom onset).

Most patients present later, and a transmural infarct is complete in 2-3 hours, after which shorter DBT will matter little. For some reason the guidelines have largely ignored this. Third, institutions may be achieving short DBTs while inadvertently sacrificing (or ignoring) other important processes of care, such as medical stabilization prior to cath, optimal PCI procedures, and administration of guideline-based medical therapies after PCI. For example, bivalirudin and ticagrelor will have a greater effect on mortality than will 20 minutes of shorter DBT in most patients with STEMI. In contrast to what we’re seeing with the DBT experience, large registry studies have confirmed the results of these randomized trials, at least in terms of bivalirudin and survival (EHJ 2010;31:561-72, JACC Intv 2010;3:669–77, Am J Cardiol 2012;110:599–606, J Interv Cardiol 2012;25:278–88). This grand experiment once again reveals the difference in validity between the results of randomized trials and observational associations.

Summary: Short DBTs are critical in a minority of patients – but the benefit of shortening DBT in broad populations is masked when diluted by the vast majority in whom 15-30 minute faster reperfusion really doesn’t make much of a difference given late presentation, spontaneous reperfusion or a small amount of myocardium at risk. Thus, if national outcomes are to be further improved we have to focus our considerable resources and efforts on other measures which have been shown to be beneficial.

Gregg W. Stone MD
NewYork-Presbyterian Hospital/Columbia University Medical Center

As both Bob & Gregg have noted, we are activating our ER/code systems for many patients who derive little or no benefit. Guidelines that focus on the patients that benefit & triage the rest to less intensive early therapy are needed, especially as we are cutting budgets everywhere.

Ted Feldman, MD
Evanston Hospital

Mort,

Very interesting discussion. There is a growing body of evidence to suggest that one of the main causes for the events in these patients is microvascular dysfunction beyond the resolution of the epicardial disease. The race for D2B time compromises the introduction of new clinical studies and the intervention to investigate the effect on the microvascular function on myocardial perfusion post PCI. We need to ensure that we still leave room and time for these interventions.

Amir Lerman, MD
Mayo Clinic

The entire history of the D2B story will eventually go down in the annals of cardiology as one of our generation's least proudest moments. This shows what happens when a process indicator based on purely observational data becomes more important than the actual clinical outcomes. Gregg says very well why the idea made sense originally. It should have been tested prospectively but we were in such earnest that that crucial step was missed, and we went on to produce guidelines and quality indicators which created an amazingly expensive resource cost -- time, energy, personnel, and actual $$$$. Even now, anyone who would say that this emperor has no (or, lets, say, very few) clothes publicly would be ridiculed.

Why it did not turn out the way we predicted is the result of numerous biologic, clinical and pharmacologic limitations and probably as Amir says, many microvascular aspects of the heart we still dont understand well. It all goes to show that the science is much smarter than we are, and also less biased.

Lloyd W. Klein, MD
Advocate Illinois Masonic

When I am on-call I sleep in the hospital. We have an in house team also. If an AMI comes through our ER, reperfusion takes a few min. If it is a transfer, the team is totally ready by the time the pt lands.

Mort, the "time is muscle" concept has tremendous variability according to each individual's anatomy and physiology. In some pts a longer delay makes no difference. I like to take no chances in case that individual needs quick reperfusion.  Also I do not like "driving like a maniac" to get to the STEMI on time.

Augusto D. Pichard, MD
Washington Hospital Center

Mort,

Here are some thoughts: “A quick thumbs up or down on whether forced reductioin of DTB is:
1) benefical for the patient: Yes, at a population level and mostly yes (rarely no) at a patient level

2) the hospital: Yes, given the emphasis on, marketing around, and public reporting of quality metrics, even accounting for the substantial cost to the system.

3) the interventionalist. Yes, in so far as it is good for patient and hospital. It also encourages our greater integration with ED and EMS (which otherwise is not naturally facilitated by our workflow) and thus helps the interventionalist’s involvement/leadership with standardization of related pathways such as Chest Pain evaluation, non STEMI ACS pathways, Cardiac Arrest, Shock, Pulomary Embolism etc.

4) a short rationale. I agree that there are downsides to the frenzied early activation eg. false activation, missed or delayed diagnoses, lack of delivery of optimal adjunctive medical therapy, or stabilization post arrest etc and these have been articulated eloquently by others and can be reduced by targeted feedback and attention. However, we all remember the 1990s when some patients (including early presenters) would be delayed and sometimes “forgotten” in the ED. The pressure to reduce D2B has surely reduced the number of such patients, improved the process, and likely saved lives although the survival curve may be flat after a certain transmurality of infarct is sustained. The issue of whether reducing D2B from 70 to 49 makes a difference. I agree that this very nuanced largely because it depends on the balance between the factors driving final infarct size such as time of symptom onset (or vessel occlusion), amount of myocardium at jeopardy, presence of pre-existing collaterals or pre-conditioning, etc. and the risk benefit ratio of P-PCI on the myocardium i.e. benefit of achieving rapid reperfusion vs further myocardial injury sustained from embolization and reperfusion injury-that can be highly variable. It is amazing to me that to date we don’t have a really good bedside clinical test (beyond the ECG) to accurately assess the extent and transmurality of injured and jeopardized myocardium that could further inform some of these decisions.
Thanks as always for the stimulating conversations.

Habib Samady, MD
Emory University Hospital

Remember, the driving force to move D2B from 90 to 60 minutes is not patient outcomes - mortality or other. NCDR data suggests mortality reduction from 4.1 at 90 min to 3.7 at 60 min, which may be clinically irrelevant. Rather the motive was by insurers who said the centers performing a median D2B times of 60 minutes would be reimbursed at higher rates. (What this obviously meant is that centers achieving 60 minutes would be paid at the existing rates and the other would find reimbursement reduced.) Our estimates of keeping a team in house was approximately $1 million per hospital. Since we have already met the goal in almost 50% of our STEMIs, the additional monetary cost would not be cost-efficient in either mortality or reimbursement.
We have had 2 staff members have MVA (motor vehicle accident) on way to STEMI, no major injuries, but one totaled his vehicle. In addition numerous citations and being pulled over for speeding, etc.

Carl L. Tommaso, MD
NorthShore Medical Group, IL

Great conversation. Appropriate surrogate initially, now suspect as little reason to believe we'll save any additional lives with further time reductions. Financial incentives are complicated, may urge more attention to lower D2B times or less, as outlined. Add in the declining incidence of STEMI and we've got the perfect storm. At least we can agree that up to now, D2B times have driven process changes that effectively took the slack out of our systems.

Kirk N. Garratt, MD
Lenox Hill Hospital

Have been following the discussion. One important issue is the potential for under treatment. As has been reported, and those of us in Massachusetts can attest to, some patients who "might" benefit are now frequently not being treated. These patients, to be evaluated effectively, would likely prolong the average D2B times and disrupt the systems we have developed. In addition to the public reporting issues that have already been discussed in a different discussion by this group, slavishly focusing on just D2B may result in incorrect treatment decisions in both directions. Patients being treated that don't need it as well as patients not being treated who should. We should not be losing site of the brass ring of better patient care. I agree that these initiatives have been important in improving processes but we need to keep it in perspective.

The second issue has been eluded to and that is the difficulty now posed to performing meaningful acute MI research. In my role with an upcoming project, I have been asked to comment on how to protect sites from the consequences of knowingly delay D2B in order to implement the research protocol requirements. There are ways to address this both with CMS and NCDR but they are not always obvious. Involvement in these studies again disrupts the "optimal" flow we have now implemented and that by itself is disruptive both for the study patients as well as for those who are not potentially eligible.

Bonnie H. Weiner, MD
Worcester Medical Center

Bonnie & Kirk bring up a great point, far removed from the original question: what are the financial incentives which maintain this rather poor process indicator as the central quality metric?

The answer is that there are several. Our hospitals perceive many advantages, including marketing vs competitors, a perception within each community of higher quality which brings other patients to its doors, and a relatively well paying DRG. That then puts pressure on the staff to meet response times that are not medically advantageous -- staff that are employees and those that are not. I am especially intrigued that mature adults with families and full lives outside the profession -- like Gus but there are others, too -- dedicate themselves to spending on call time away from all that makes life fun & worthwhile to meet these arbitrary goals. It shows true dedication to our calling to do this.

It also demonstrates how & why power is wielded in contemporary medicine. Pynchon couldnt have concocted a more clear fictional story of who controls us than this real one. No one should be getting into auto accidents or risk being injured for whatever minimal advantages exist from meeting a D2B time goal. And as cath lab directors, we should make that clear to our staff -- this is important to a point, but really, not that important.

Lloyd W. Klein, MD
Advocate Illinois Masonic

Mort:
Thanks for setting up a most interesting dialog…
There is no doubt that the focus on D2B has driven process development which has improved patient care. The problem is that a myopic focus on a single metric, D2B, will draw attention away from other important high impact factors, e.g., anticoagulation, anti-platelet strategy (See Gregg Stone’s Note) as well as more basic items, balloon/stent sizing etc.
Question: Are there contemporary data (CRF, DCRI) which tests the association of D2B with other procedure related quality outcomes, e.g., bleeding? Would be interesting to know.

Aaron V. Kaplan, MD
Dartmouth-Hitchcock Medical Center