Direct Admission to PCI-Capable Center Linked With Lower All-Cause Mortality

Patients with STEMI taken directly to a PCI-capable hospital are more likely to be alive at 3 years when compared with patients transferred for primary PCI, according to the results of a new analysis.

The mortality benefit, according to lead investigator Krishnaraj Rathod, MBBS, PhD (Barts Health NHS Trust, London, England), and colleagues, is “most likely due to long call-to-balloon times in patients transferred from other hospitals.”

Presented at the European Society of Cardiology’s Acute Cardiovascular Care 2019 conference, the new study is an observational analysis of approximately 125,000 patients treated at eight tertiary cardiac centers between 2005 and 2015. “In terms of the evidence behind what we’re doing, we know that patients taken directly to a tertiary center for PCI do way better than patients transferred from another hospital,” Rathod told TCTMD.

He pointed out, however, that a 2013 analysis of 515 hospitals included in the CathPCI registry showed reductions in door-to-balloon times in patients taken directly to PCI centers, but unchanged in-hospital mortality rates. For that reason, they wanted to assess longer-term outcomes in addressing the question of direct admission versus transfer in STEMI patients in a large observational database.

In total, 31.6% of STEMI patients were first taken to another hospital before being transferred to a center with PCI capabilities, although the rates of interhospital transfer declined and direct admissions to a cardiac care center increased over time.

Currently, European guidelines recommend prehospital management of STEMI patients based on regional networks to deliver reperfusion therapy as quickly as possible, the goal being less than 90 minutes. To achieve that goal, they recommend bypassing non-PCI hospitals or hospitals without a 24/7 primary PCI program. If a patient is transferred to a PCI-capable hospital, the guidelines recommend that teams bypass the emergency department and take patients directly to the catheterization laboratory.

In this latest analysis, the patients transferred for primary PCI had higher rates of previous MI and previous CABG, as well as a higher prevalence of diabetes and a history of smoking, when compared with the transferred patients. However, patients directly admitted for primary PCI were older and more commonly had left ventricular impairment, as well as were more likely to be in cardiogenic shock, than the patients transferred for coronary revascularization.  

Symptom-to-balloon times were significantly higher among patients transferred between hospitals for primary PCI than among the direct admissions (median 216 min vs 164 min; P < 0.0001). Similarly, the time from the first emergency medical services (EMS) call to balloon was significantly higher among the transferred patients (median 160 min vs 108 min; P < 0.0001). Procedural success and in-hospital MACE rates were similar between the two groups.

After a median follow-up of 3.0 years, the rate of all-cause mortality among those taken directly to the cardiac care center was 17.4%, compared with 18.7% for those transferred from another hospital. After regression adjustment, which included the propensity score as a covariate in the hazard model, direct admission to a primary PCI hospital was associated with a significant 20% lower risk of all-cause mortality. In a propensity-matched analysis, direct admission for primary PCI was associated with a significant 14% reduction in the risk of all-cause death.

In a press release accompanying the study, Rathod states that their results suggest a diagnosis of STEMI was not made by EMS but instead by the first hospital before the patient was transferred. “All patients with STEMI should be admitted directly to a primary PCI center within 90 minutes of diagnosis by electrocardiogram, which is done by ambulance teams,” he states.

“We need a proper randomized trial to answer the question fully, but this gives a good idea of real-world practice, which is one the reasons we looked at this question in detail,” Rathod told TCTMD.  

Possible Confounding, but Direct Admission Remains a ‘Win-Win’

Mamas Mamas, BMBCh (Keele University, Stoke-on-Trent, England), who was not involved in the study, said STEMI patients are routinely taken directly to a primary PCI-capable center based on ambulance triage. Different parts of the United Kingdom rely on different methods of stratifying patients to different centers, though, with some relying entirely on the ambulance interpretation of the ECG and others electronically sending the ECG to the PCI-capable center if they are uncertain about the diagnosis.

“The only people who aren’t directly transferred are either those who are thought to be too sick—they’re taken to the nearest hospital—or those in whom there is diagnostic uncertainty,” he told TCTMD. Such patients might include those in cardiogenic shock who are electrically unstable, or a patient with left bundle branch block and an atypical history. “There might also be patients where there are issues with the medical history and it’s uncertain if it’s in the patient’s best interest to be taken to a PCI-capable center,” said Mamas. “Those sorts of patients are usually taken to the local hospital where the doctors can assess them and they can then liase with the PCI-capable hospital.”

You get the patient quick to your center and you increase the amount of salvageable myocardium. Mamas Mamas

For that reason, Mamas suspects some bias may be introduced into the observational study, noting that the 20% reduction in all-cause mortality is larger than he would have predicted given the 52-minute difference in the call-to-balloon time between the two groups. Additionally, there is an element of “historical bias” in that transfer was more common in the past than it is today.

“A large proportion of patients in the transfer arm were historical patients,” said Mamas. “You’re comparing patients from maybe a decade ago to more contemporary patients, and the better outcomes might simply reflect advances in the management of patients.”

Nonetheless, while there is an element of confounding in the present observational analysis, Mamas believes that “some of the mortality benefit probably is real.” Overall, direct admission to a PCI-capable hospital is a “win-win” for patients and physicians, he said. “You get the patient quick to your center and you increase the amount of salvageable myocardium.”