The Hallway Consult — Issue #27: Ambulatory ECG for Unexplained Syncope, Oseltamivir in Critically Ill Influenza, and Prehospital Heparin in STEMI

ASPIRED: 14-Day Ambulatory ECG After Unexplained ED Syncope

Syncope that stays unexplained after a full ED workup is one of the most common dispositions we make with some unease. The concern is a paroxysmal arrhythmia that a 12-lead and a few hours on telemetry never catch. Prolonged ambulatory monitoring is the obvious answer, and in many systems getting it is slow and inconsistent. ASPIRED tested whether starting it right away, from the ED, changes what happens to these patients.

This was an open-label RCT at 45 UK hospitals. Adults whose syncope was still unexplained after ED evaluation were randomized 1:1 to 14-day ambulatory ECG monitoring or to whatever standard care for unexplained syncope looked like at each site. A total of 2,234 patients were randomized (1,123 monitoring, 1,111 standard care). The mean age was 58 and 52% were male. After excluding patients with no follow-up, 1,970 made up the primary analysis.

The primary outcome was the mean number of patient-reported syncope episodes at 1 year, and it was not different: 1.37 episodes with monitoring versus 1.58 with standard care (incidence rate ratio 0.89, 95% CI 0.68 to 1.18, P=0.42). Adverse events were more common with monitoring (49 vs. 8), with 1 serious adverse event in each group.

The useful framing: this trial asked whether early monitoring prevents the next faint, and in this trial it didn't. That isn't the same as saying monitoring is worthless. Diagnostic yield, downstream treatment, and harder outcomes are separate questions, and the published abstract doesn't report them. Until those secondary results are out in full, don't take this as proof that monitoring "finds more and saves lives." All we can say is that it didn't reduce recurrent syncope.

Bottom line: In this 2,234-patient UK RCT, starting 14-day ambulatory ECG monitoring from the ED for unexplained syncope did not reduce patient-reported syncope episodes at 1 year compared with standard care (IRR 0.89, P=0.42). Reflexively strapping a monitor on every unexplained syncope patient isn't supported if the goal is fewer recurrences. Arranging monitoring for patients with real arrhythmic concern is still reasonable, but this trial doesn't show it changes the primary outcome.

Reed MJ, Goodacre S, Weir CJ, et al; ASPIRED Investigators. Immediate Ambulatory Electrocardiographic Monitoring in Syncope. N Engl J Med. 2026 Aug 31.

REMAP-CAP: Oseltamivir May Be Harmful in Critically Ill Influenza

Oseltamivir is close to automatic for the flu patient headed to the ICU, and a number of guidelines recommend it. The evidence underneath that recommendation comes almost entirely from outpatients and less sick patients, where the benefit is less than a day of symptoms. Before REMAP-CAP, no randomized trial had tested oseltamivir in ICU patients with severe influenza.

REMAP-CAP is a global Bayesian adaptive platform trial for severe respiratory infection. In its Influenza Antiviral Domain, critically ill patients aged 12 and older with influenza were randomized to oseltamivir (5 or 10 days) or no oseltamivir. All other care was left to the treating team, and patients were followed to 90 days. At a scheduled adaptive analysis, the oseltamivir interventions crossed the trial's predefined statistical threshold for inferiority. In the investigators' plain-language summary, more patients who received oseltamivir died within 90 days, and they conclude it is "highly likely" oseltamivir is harmful in this population. They don't yet know why.

Now the caveats, and they are significant. These results are currently a preprint that has not been peer-reviewed. Preliminary numbers presented at the Critical Care Reviews meeting have since been revised in the manuscript. The finding applies only to patients sick enough for the ICU. The investigators explicitly say it tells us nothing about ward patients, outpatients, or children under 12, and the existing evidence for outpatient treatment and prophylaxis stands. A Bayesian platform result based on a predefined threshold is not the same thing as a conventional P-value, and the magnitude of harm will matter once the peer-reviewed paper is out.

For the ED, the practical change is narrow but real. The "start Tamiflu before they go upstairs" order for a flu patient being admitted to the ICU is now an open question, not a given. That's a conversation to have with your ICU colleagues, not a solo protocol change.

Bottom line: In the REMAP-CAP Influenza Antiviral Domain, oseltamivir met a predefined threshold for inferiority in critically ill patients 12 and older, with more deaths at 90 days than no antiviral. The investigators conclude it is likely harmful in this group. This is a preprint, not yet peer-reviewed. It applies only to ICU-level influenza and says nothing about outpatient or ward patients. Until the peer-reviewed paper lands, stop treating oseltamivir as automatic for the critically ill flu patient, and talk it through with your ICU.

REMAP-CAP Investigators. REMAP-CAP Influenza Antiviral Domain (oseltamivir). Preprint, SSRN (abstract_id 7172531), 2026; not yet peer-reviewed.

HEPARIN-STEMI: Prehospital Unfractionated Heparin Before Primary PCI

STEMI systems shave minutes everywhere. Heparin timing is one of the few places where practice still varies a lot. Some systems give unfractionated heparin at first medical contact, and others hold it until the patient is on the cath lab table. The theory behind early dosing is simple: an artery that has started to reopen by the time it's imaged is a better artery. HEPARIN-STEMI tested that directly.

This was a single-center, open-label RCT in Ljubljana, Slovenia, which runs a mature STEMI network. Patients with STEMI and 6 hours or less of symptoms were randomized to a 70–100 IU/kg UFH bolus at first prehospital medical contact (plus a supplemental dose before PCI, titrated to ACT ≥250 seconds) or to standard UFH given at the time of PCI. From 2022 to 2025, 593 patients were randomized (298 pretreatment, 295 control). Time from symptoms to angiography was similar (median 145 vs. 150 minutes), and pretreated patients got heparin a median of about an hour before angiography.

The primary efficacy endpoint, TIMI 2–3 flow in the infarct-related artery at initial angiography, was seen in 43% of pretreated patients versus 27% of controls (RR 1.59, 95% CI 1.27–1.98, P<0.001). That's an absolute 16-point increase in early patency. The primary safety endpoint, BARC 3–5 bleeding during the index hospitalization, was not different (2.4% vs. 2.0%, P=0.79).

Keep the endpoint in perspective. Early patency is a surrogate. It's a biologically sensible one, and the trial doesn't report mortality or infarct size. It also comes from one center with a tight system, and the bleeding result is reassuring but based on small event numbers. Still, the trade looks favorable. Giving heparin earlier is cheap and simple, and in this trial it didn't increase bleeding while meaningfully increasing the number of arteries already open at angiography.

Bottom line: In this 593-patient single-center RCT, giving UFH at first prehospital contact for STEMI increased infarct-artery patency at initial angiography (TIMI 2–3: 43% vs. 27%) without increasing major bleeding (2.4% vs. 2.0%). The endpoint is a surrogate and hard-outcome data are lacking, but this is encouraging evidence for systems that give heparin early. It's reasonable for EMS and ED protocols to move heparin upstream rather than waiting for the cath lab.

Fister M, Noc M, Radsel P, Bunc M, Franco D, Goslar T; HEPARIN-STEMI Trial. Prehospital Heparin Administration in Patients With STEMI Undergoing Primary PCI: HEPARIN-STEMI Randomized Controlled Trial. Circulation. 2026;153(20):1526-1534.

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— The Hallway Consult team