Structural Heart · Electrophysiology

Stunning the Appendage: Pre-Emptive Ablation May Cut Peridevice Leaks After LAAO

New nonrandomized data suggest that ablating the left atrial appendage before closure devices are deployed shrinks residual flow around the implant — and the physiologic story behind it is straightforward.

Cardiology & Physician-Investor Briefing · Updated July 2026

Peridevice leaks remain the most persistent nuisance in left atrial appendage occlusion (LAAO) therapy despite a decade of device refinement.

A nonrandomized study called STUN-AF, presented at New York Valves 2026, offers a plausible fix.

Among 317 patients undergoing combined atrial fibrillation ablation and appendage closure, ablating the appendage itself before implanting the occluder nearly doubled the rate of complete appendage sealing by four months.

By one year, 96% of appendage-ablated patients had no detectable leak on imaging, compared with 58% of those who skipped the extra step.

Why Peridevice Leaks Matter

Roughly a quarter to a third of patients have some residual flow around a closure device on follow-up imaging, even with modern iterations like Watchman FLX Pro.

That residual flow is not a benign imaging footnote.

Pooled five-year follow-up from the original Watchman device trials found that patients with any leak up to 5 mm at one year had roughly double the risk of ischemic stroke or systemic embolism compared with patients whose appendages were fully sealed, an effect driven mainly by nondisabling strokes.

A separate meta-analysis using a strict CT definition of patency found that more than half of patients had some detectable flow behind the device at a mean of roughly five months, and patency tracked with higher thromboembolism and mortality.

The takeaway echoed by the presenting electrophysiologist was blunt: leaks are bad, and the goal of the procedure should be true anatomic obliteration, not just a leak below an arbitrary size cutoff.

The STUN-AF Hypothesis

Beyond anatomic mismatch between device and appendage, investigators suspected that residual mechanical contraction of the appendage itself was working against device healing.

A contracting appendage can create intermittent flow around an otherwise well-seated device and interfere with the endothelialization needed to seal it permanently.

The STUN-AF concept was to electrically stun the appendage — eliminating its contractile motion — before deploying the occluder, so the device sits still long enough to heal in place.

P < 0.001 for both comparisons; nonrandomized, three-center US cohort (n = 317).

Study Design and Findings

STUN-AF enrolled 317 patients (mean age 76 years, 58% men) with atrial fibrillation or flutter undergoing concomitant pulsed-field ablation (PFA) and LAAO at three US centers.

Pulmonary vein isolation was performed predominantly with the Farawave catheter (62% of cases) and the Sphere-9 catheter (34%), with LAAO performed using Watchman FLX or FLX Pro devices.

After standard pulmonary vein isolation, 70% of patients underwent additional ablation targeting the appendage itself before device implantation, while 30% proceeded directly to closure.

On multivariable analysis, prior appendage ablation was the only independent predictor of complete sealing at four months, cutting the odds of any leak by roughly 80%.

Mechanistically, appendage ablation measurably reduced LAA emptying velocities, and lower velocities independently tracked with lower odds of leak — supporting residual contractility as a modifiable target.

Adverse events were reassuringly low and similar between groups, with 98% of patients free of any periprocedural complication.

There was a numerically lower stroke rate at three months in the ablation group (0.5% vs 2.1%), though the study was explicitly underpowered to detect differences in hard clinical outcomes.

Table 1. STUN-AF at a Glance

Nonrandomized, three-center US study of concomitant PFA and LAAO

Parameter	Detail
Population	317 patients with AF/flutter undergoing same-session PFA + LAAO
Mean age / sex	76 years; 58% men
Intervention	Additional LAA-directed ablation before device implantation (70% of cohort)
Comparator	LAAO without prior LAA ablation (30% of cohort)
No-leak rate, 4 months	71% (ablation) vs 36% (no ablation), P < 0.001
No-leak rate, 12 months	96% (ablation) vs 58% (no ablation), P < 0.001
Periprocedural adverse events	98% free of events overall; no between-group difference
Key limitation	Nonrandomized; underpowered for stroke/clinical endpoints

Where This Fits in Practice

The presenting investigator noted that appendage ablation is now performed routinely at the enrolling center whenever a patient is already undergoing combined AF ablation and LAAO in the same session.

The economics are a different story for isolated LAAO procedures, where opening an additional ablation catheter purely to stun the appendage is not currently reimbursed and unlikely to be practical.

That reimbursement gap is not hypothetical: the 2026 Medicare Physician Fee Schedule proposed cutting the work relative value units for LAAO (CPT 33340) by roughly 27%, a change professional societies have publicly opposed as a stroke-prevention access issue.

On the hospital side, CMS has already created a dedicated concomitant MS-DRG (317) that bundles ablation and appendage closure performed together, which is the payment structure under which same-session LAA-ablation-before-LAAO would most naturally fit.

An outside discussant, an interventional cardiologist unaffiliated with the trial, agreed that a hypercontractile appendage is a familiar culprit when a device "does not sit right," and that stilling the appendage helps it anchor.

Both the presenter and discussant called for a randomized trial to confirm a clinical benefit, while acknowledging that low absolute stroke rates make such a trial logistically difficult.

Sequence used in the ablation-first arm of STUN-AF; timing within the same operative session.

The Device and Company Landscape

For physician-investors tracking the structural heart and electrophysiology space, this data point sits at the intersection of two fast-growing device categories inside the same procedure.

Boston Scientific supplies both the dominant LAAO platform and one of the two leading PFA catheters used in the study, giving it exposure on both sides of a combined procedure.

Medtronic's Affera mapping and ablation system with the Sphere-9 catheter was the second-most-used PFA platform in the cohort, and offers a dual pulsed-field/radiofrequency option in a single catheter.

Table 2. Devices and Companies Referenced in STUN-AF

Approximate market data as of early July 2026; for general context only

Device	Category	Manufacturer (Ticker)	Share Price	Analyst Consensus
Watchman FLX / FLX Pro	LAAO occluder	Boston Scientific (NYSE: BSX)	~$45	Buy; 12-mo target ~$75
Farawave / FARAPULSE	Pulsed-field ablation catheter	Boston Scientific (NYSE: BSX)	~$45	Buy; 12-mo target ~$75
Sphere-9 / Affera	Dual-energy (PFA + RF) mapping and ablation catheter	Medtronic (NYSE: MDT)	~$79	Buy; 12-mo target ~$98

Both companies' PFA franchises are still maturing commercially, and the LAAO growth trajectory itself has recently been a point of investor scrutiny, with several analysts trimming price targets after commentary on slowing Watchman utilization.

As always, published analyst consensus ratings and price targets are snapshots that shift with each earnings cycle, and past device adoption trends are not a guarantee of future procedural volumes or share performance.

Illustrative Case

A 76-year-old with paroxysmal atrial fibrillation and a prior gastrointestinal bleed on anticoagulation is scheduled for same-day pulmonary vein isolation and left atrial appendage closure.

Pre-procedural imaging shows a windsock-shaped appendage with brisk emptying velocities, a morphology previously associated with higher rates of residual device leak.

Based on the STUN-AF experience, the operator elects to extend ablation to the ostium and proximal appendage after pulmonary vein isolation and before device deployment.

Follow-up transesophageal echocardiography at four months shows complete appendage sealing, and the patient is transitioned off anticoagulation per protocol.

Bottom Line

In a nonrandomized 317-patient series, ablating the left atrial appendage before device closure roughly doubled complete-sealing rates at four months and nearly closed the gap entirely by one year.

The physiologic rationale — that residual appendage contractility disrupts device healing — is biologically coherent and measurable via emptying velocities on imaging.

Clinical outcome data remain underpowered, reimbursement for isolated LAAO does not currently support routine adjunctive ablation, and a randomized trial is unlikely given low event rates, so this remains a reasonable adjunct in combined-procedure patients rather than a new standard of care.

References

1. STUN-AF: Ablation Before LAAO May Reduce Peridevice Leaks. TCTMD, July 2026.
2. Peridevice Leaks After LAA Occlusion Signal Poorer 5-Year Outcomes. TCTMD.
3. New York Valves 2026 Late-Breaking Research Preview. Cardiovascular Research Foundation.
4. WATCHMAN FLX Pro Left Atrial Appendage Closure Device. Boston Scientific.
5. FARAWAVE Pulsed Field Ablation Catheter. Boston Scientific.
6. Sphere-9 Catheter, Affera Mapping and Ablation System. Medtronic.
7. CMS Finalizes New Concomitant MS-DRG for LAAO and Ablation for Atrial Fibrillation. Heart Rhythm Society.
8. CMS Reduces LAAO Value in Proposed 2026 Medicare Physician Fee Schedule. American College of Cardiology.
9. Boston Scientific Corporation (BSX) Stock Overview. StockAnalysis.com.
10. Medtronic plc (MDT) Stock Overview. StockAnalysis.com.

Physician education disclaimer: This article summarizes publicly reported conference data and published literature for physician education. It is not a substitute for review of full trial methodology, primary sources, or institutional protocols, and should not be used to guide individual patient care decisions in isolation.

Financial education disclaimer: Company, ticker, and market data are provided for general financial education only and do not constitute investment advice or a recommendation to buy or sell any security. Share prices and analyst ratings are time-sensitive snapshots that change frequently; past performance does not predict future results. Readers should consult a licensed financial advisor before making investment decisions.

Clinical Cardiology · Heart Failure

The Second Universal Definition of Heart Failure: What Changes for Practice

A new joint consensus retires rigid ejection-fraction cutoffs, expands how clinicians classify the causes of heart failure, and reframes the syndrome as a dynamic rather than fixed diagnosis.

9-minute read · Physician education · Includes physician-investor context

A joint writing group representing the American Heart Association, the American College of Cardiology, the European Society of Cardiology, and the World Heart Federation has published the Second Universal Definition of Heart Failure.

The document updates and reaffirms the first universal definition published in 2021, which introduced pre-heart failure as stage B and standardized previously ambiguous terminology.

It is not a clinical practice guideline, but a shared vocabulary intended to align trials, registries, and day-to-day documentation across specialties.

For a cardiologist writing notes, coding encounters, or screening for enrollment eligibility, the changes are practical rather than theoretical.

Why the Ejection-Fraction Cutoffs Had to Go

The first universal definition relied on specific left ventricular ejection fraction thresholds to separate HF with reduced ejection fraction from HF with preserved ejection fraction.

The writing committee concluded that those cutoffs were arbitrary given the known variability of echocardiographic measurement of LVEF and unresolved debate over whether thresholds should differ by sex, age, or ethnicity.

The lower limit of normal LVEF is now cited as approximately 53% for women and 52% for men, with slightly higher thresholds among individuals of Asian descent, reinforcing that no single number applies uniformly.

The new document therefore collapses the classification into three clinically actionable groups: reduced, preserved, and improved ejection fraction, without anchoring to a specific numeric boundary.

Figure 1 · HF Trajectory Across Stages

Stage AAt risk

Stage BPre-HF

Stage CSymptomatic HF

Stage DAdvanced HF

Improvement
(LVEF rises, abnormalities persist)

Remission
(normalized LVEF, minimal symptoms)

Recovery
(sustained normalization — minority)

Reframing Cause: Eighteen Pathogenic Groups Instead of Two

Clinical practice has long sorted heart failure into just ischemic and nonischemic cardiomyopathy, a split the committee says omits the treatable causes of dilated and hypertrophic disease.

A patient whose underlying cause is cardiac amyloidosis, for instance, benefits from disease-targeted therapy well beyond standard heart failure management.

The new framework proposes a pathogenic classification independent of ejection fraction, spanning ischemic, hypertensive, valvular, arrhythmia-related, infiltrative, infective, inflammatory, toxic, heritable, pericardial, metabolic and nutritional, pregnancy-related, stress-induced, pulmonary or right-sided, congenital, high-output, other, and idiopathic causes.

The intent is to standardize how causes are recorded in registries and trials, since the same patient population can otherwise be labeled inconsistently across studies.

Table 1 · Stages in the Development and Progression of HF

Stage	Definition
A — At risk	Hypertension, atherosclerotic disease, diabetes, obesity, cardiotoxin exposure, or family history of cardiomyopathy, without symptoms, structural change, or elevated biomarkers.
B — Pre-HF	Structural or functional cardiac abnormality, or elevated natriuretic peptide or troponin, without current or prior symptoms.
C — HF	Current or prior symptoms or signs caused by a structural or functional cardiac abnormality.
D — Advanced HF	Severe symptoms at rest or minimal exertion, recurrent hospitalization despite guideline-directed therapy, or need for inotropes, mechanical support, transplantation, or palliative care.

HF with Improved Ejection Fraction Is Not a Cure

Patients whose previously reduced LVEF rises or normalizes on therapy are classified as HF with improved ejection fraction, a category first formalized in the 2022 heart failure guideline.

The document is explicit that improvement in EF does not equal disease resolution, and these patients remain at risk for recurrent left ventricular dysfunction, hospitalization, and sudden cardiac death.

Once a diagnosis of symptomatic heart failure is established, the individual is generally considered to carry that diagnosis permanently, even if the clinical picture improves substantially.

Practically, this means continued guideline-directed medical therapy and longitudinal surveillance rather than a taper toward discontinuation once an echocardiogram looks reassuring.

A related but distinct state, HF in remission, applies to select asymptomatic patients with normalized LVEF and stable biomarkers, while true recovery with sustained normalization of structure, function, and symptoms is reached by only a minority.

Worsening HF and Decompensated HF Are Now Distinguished

The consensus separates worsening HF, a progressive deterioration in symptoms or signs in a patient with an established diagnosis, from new-onset presentations or symptom flares driven by unrelated events such as infection or nonadherence.

Decompensated HF is defined more narrowly as the point at which treatment intensification is required, commonly an increase in diuretic dose, addition of combination diuretic therapy, or escalation to advanced interventions.

The distinction matters for documentation and for trial eligibility, since decompensation implies a treatment threshold rather than simply a worse-feeling patient.

Recognizing HF Mimics

The document devotes explicit attention to conditions that resemble heart failure without being pathophysiologically driven by myocardial neurohormonal activation.

Chronic kidney disease, third-trimester pregnancy, and obesity with deconditioning can all produce dyspnea, edema, and exertional limitation that mimic HF, sometimes accompanied by falsely reassuring natriuretic peptide levels.

Roughly half of the heart failure population across the ejection-fraction spectrum has coexisting coronary disease, and myocardial ischemia itself can serve as a mimic, a comorbid driver, or a trigger of decompensation.

Geography Still Shapes Cause

Ischemic heart disease accounts for more than half of HF cases across Western high-income and Eastern European regions but under 10% in sub-Saharan Africa, where hypertensive heart disease predominates instead.

Chagas disease remains a leading cause in parts of Latin America, while chronic obstructive pulmonary disease contributes disproportionately to HF prevalence in South and East Asia.

The committee also flags a near-absence of sub-Saharan African participants in major heart failure trials, a gap that limits how confidently global guidance can be generalized.

Figure 2 · Leading Contributors to HF Prevalence by Region (Illustrative, Global Burden of Disease-Derived)

50%+

Ischemic heart disease
Western / E. Europe

33%

Hypertensive disease
Sub-Saharan Africa

38%

COPD-related
South Asia

16%

Alcoholic CM
Eastern Europe

<10%

Ischemic disease
Sub-Saharan Africa

The GDMT and Company Landscape

None of the four pillars of guideline-directed medical therapy change under the new definition, but the reclassification affects which patients trial sponsors and payers consider eligible for these agents.

For physician-investors tracking the space, the table below summarizes representative agents, current approximate cash pricing, and the companies behind them.

Table 2 · Representative GDMT Agents and Market Context

Class / Agent	Brand	Approx. Cash Price (30-day)	Company (Ticker)
ARNI — sacubitril/valsartan	Entresto	~$600–700 brand; generic ~$45–90 with discount card; Medicare Part D negotiated ~$295	Novartis (NVS)
SGLT2 inhibitor — dapagliflozin	Farxiga	~$530–780 brand; GoodRx cash ~$288; generic available	AstraZeneca (AZN)
SGLT2 inhibitor — empagliflozin	Jardiance	~$360–830 brand; no generic; copay card as low as $0	Boehringer Ingelheim (private) / Eli Lilly (LLY)
Nonsteroidal MRA — finerenone	Kerendia	~$550–600 brand; manufacturer copay assistance available	Bayer (BAYRY)
Steroidal MRA — spironolactone	generic (Aldactone)	<$15 generic	Multiple generic manufacturers

Pricing is a snapshot subject to change, and it reflects list or cash pricing rather than what any individual patient pays after insurance, rebates, or Medicare Part D redesign under the Inflation Reduction Act.

This is general financial education, not personalized investment advice, and analyst views on any of these names can shift quickly around earnings and pipeline readouts.

What Actually Changes at the Bedside

Staging from stage A through stage D is unchanged, so risk-factor counseling and pre-HF surveillance workflows remain valid as written.

What changes is the language used when documenting ejection-fraction category and cause, favoring the simplified three-group EF framework and the expanded eighteen-category cause list over the old ischemic-versus-nonischemic shorthand.

Clinicians involved in trial screening or registry data entry should expect case-report forms to migrate toward this vocabulary over the next several guideline cycles.

Case Vignette

A 68-year-old with a history of anterior myocardial infarction and an LVEF that improved from 30% to 46% on quadruple guideline-directed therapy is told by a well-meaning relative that they are "cured."

Applying the second universal definition, this patient is correctly classified as HF with improved ejection fraction, not as a patient in remission or recovery, since residual scar and biomarker elevation persist.

The clinical implication is continuation of all four GDMT pillars, periodic re-imaging, and counseling that the diagnosis of heart failure remains permanent despite the reassuring echocardiogram.

Bottom Line

The second universal definition of heart failure moves away from rigid LVEF cutoffs toward three clinically actionable phenotypes, expands cause classification from two categories to eighteen, and reinforces that improvement in ejection fraction is not equivalent to cure.

Staging (A through D) and the core four-pillar GDMT approach are unchanged, but documentation language, trial eligibility criteria, and registry data fields are likely to evolve toward this new framework over time.

References

1. AHA/ACC/ESC/WHF Expert Consensus Document: Second Universal Definition of Heart Failure. Global Heart, 2026.
2. Second Universal Definition of HF Focuses on Phenotypes and Etiology. TCTMD, July 2026.
3. Universal Definition and Classification of Heart Failure: A Step in the Right Direction. American College of Cardiology, 2021.
4. Entresto Pricing and Savings. GoodRx, accessed 2026.
5. Farxiga vs. Jardiance: Comparing SGLT2 Inhibitors. GoodRx, 2026.

Disclaimer: This article is intended for physician education and general clinical discussion; it does not constitute individualized medical advice and should not replace clinical judgment or current society guidelines. Drug pricing and company information are provided for general financial education only, not as personalized investment advice; pricing is time-sensitive and subject to change, and past performance of any security does not predict future results. Consult a licensed financial advisor before making investment decisions.