Imperative Care Reports New SYMPHONY-PE Analysis Highlighting Potential Benefits of Early Thrombectomy as Symphony Use Surpasses 500 U.S. Patients
Imperative Care, a medical technology company focused on improving treatment options for patients with thromboembolic disease, has announced new clinical findings from a post-hoc analysis of its SYMPHONY-PE Trial, offering fresh insight into the potential benefits of performing mechanical thrombectomy earlier in patients with intermediate-risk pulmonary embolism. The company also revealed an important commercial milestone: more than 500 pulmonary embolism patients in the United States have now been treated with the Symphony Thrombectomy System since its commercial launch in September 2025.
Together, the new clinical data and the commercial adoption milestone mark a significant moment for Imperative Care as it seeks to strengthen Symphony’s role in the evolving treatment landscape for pulmonary embolism, or PE. The latest analysis suggests that patients treated within 12 hours of diagnosis may experience greater improvement in key hemodynamic and cardiac function measures compared with those treated later, while maintaining a comparable safety profile. At the same time, the growing number of patients treated in real-world practice indicates increasing physician confidence in the system and momentum behind the company’s effort to establish a new standard for catheter-based thrombectomy in PE.
The findings were published in Circulation: Cardiovascular Interventions in a paper titled “Is There a Golden Hour for Thrombectomy in Intermediate-Risk Pulmonary Embolism? Insights from SYMPHONY-PE.” The study adds to a growing body of evidence exploring not only whether mechanical thrombectomy can benefit patients with pulmonary embolism, but also whether the timing of intervention may meaningfully influence outcomes.
A Growing Focus on Timing in Pulmonary Embolism Care
Pulmonary embolism is a serious and potentially life-threatening condition caused by a blood clot that blocks one or more arteries in the lungs. It can place significant strain on the heart—particularly the right ventricle, which must work harder to pump blood through obstructed pulmonary vessels. In intermediate-risk PE, patients are hemodynamically stable but show signs of right heart strain or other indicators suggesting an elevated risk of deterioration. Managing these patients remains one of the most debated areas in cardiovascular and interventional care, as physicians weigh the urgency of clot removal against procedural considerations, patient stability, and the availability of therapeutic options.
Mechanical thrombectomy has emerged as an increasingly important tool in this setting because it allows physicians to physically remove clot from the pulmonary arteries without relying solely on thrombolytic drugs, which can carry bleeding risks. But as the use of thrombectomy expands, another question has become increasingly relevant: does the timing of the procedure matter? Specifically, are outcomes better when intervention is performed very early after diagnosis rather than later in the patient’s hospital course?
Imperative Care’s latest SYMPHONY-PE analysis was designed to explore that question.
Post-Hoc Analysis Suggests Earlier Treatment May Improve Acute Recovery
The newly reported analysis examined data from patients enrolled in the SYMPHONY-PE Trial and compared outcomes based on how quickly thrombectomy was performed after diagnosis. Investigators divided patients into two groups according to the time from diagnostic computed tomography pulmonary angiography, or CTPA, to mechanical thrombectomy. Early treatment was defined as intervention within less than 12 hours of diagnosis, while late treatment was defined as intervention at 12 hours or later.
Among the 109 patients included in the analysis, 44%—or 48 patients—underwent early thrombectomy, while the remainder were treated in the later time window. Researchers then compared the two groups across several efficacy and safety endpoints, focusing particularly on changes in pulmonary artery pressure and measures of right ventricular strain.
The findings suggest that earlier intervention may be associated with more substantial short-term improvements in the cardiovascular consequences of pulmonary embolism. According to the analysis, patients treated within 12 hours experienced a greater reduction in mean pulmonary artery pressure, or PAP, than those treated later. Mean PAP fell by 8.6 in the early thrombectomy group compared with 5.8 in the late-treatment group, a difference that reached nominal statistical significance with a p-value of 0.006.
This is a notable observation because pulmonary artery pressure is a direct indicator of the stress imposed on the pulmonary circulation and the right side of the heart. A more pronounced reduction in PAP after clot removal may reflect more rapid unloading of the right ventricle and improved blood flow through the lungs, both of which are central goals of PE treatment.
Improvement in Right Ventricular Function Also Favored Early Intervention
In addition to pulmonary artery pressure, the analysis evaluated changes in the right ventricle-to-left ventricle ratio, commonly referred to as the RV/LV ratio. This metric is widely used in pulmonary embolism because it provides a measure of right heart strain. A higher RV/LV ratio suggests the right ventricle is enlarged and under pressure, which can be a sign of more severe disease and a predictor of worse outcomes.
Patients treated earlier in the SYMPHONY-PE analysis showed a larger reduction in RV/LV ratio from baseline to 48 hours than those treated later. Specifically, the reduction was 0.52 in the early thrombectomy group versus 0.37 in the late-treatment group. Although this difference did not reach conventional statistical significance, with a p-value of 0.071, the numerical trend favored early treatment and suggests a potentially meaningful signal in terms of cardiac recovery.
Taken together, the reductions in pulmonary artery pressure and RV/LV ratio support the hypothesis that intervening sooner after diagnosis may accelerate reversal of the hemodynamic burden imposed by pulmonary embolism. For clinicians managing intermediate-risk PE patients, that possibility is particularly important, because the goal is often to stabilize and improve the patient before they deteriorate into a more dangerous state.
Higher-Risk Patients May Benefit Most from Earlier Thrombectomy
One of the more intriguing findings from the analysis was that the differences in efficacy between early and late thrombectomy appeared greatest among higher-risk patients as measured by the Composite Pulmonary Embolism Shock, or CPES, score. This observation suggests that timing may be especially relevant in patients who present with more severe physiological compromise or a greater risk of progression.
Although the study was not designed to definitively identify which patients benefit most from early intervention, the CPES finding raises important questions for future research. It may be that not all intermediate-risk PE patients derive the same magnitude of benefit from urgent thrombectomy, and that certain clinical features—such as greater right ventricular dysfunction, elevated biomarkers, or worsening respiratory status—could help identify those who should be treated sooner rather than later.
This is precisely the kind of issue that could shape future clinical practice if confirmed in prospective studies. If early thrombectomy proves particularly advantageous in higher-risk subsets of intermediate-risk PE, it could influence hospital workflows, triage decisions, and referral patterns for catheter-based intervention.
Safety Profile Remained Favorable Across Both Timing Groups
While efficacy is a central question in thrombectomy timing, safety is equally critical. Any argument for earlier intervention must be balanced against the possibility that faster treatment could increase procedural complications or adverse events. In this regard, the SYMPHONY-PE analysis offers reassuring results.
The study found no significant difference in major adverse events within 48 hours between patients who underwent early thrombectomy and those who were treated later. There was one major adverse event reported in the early-treatment group and none in the late-treatment group. Importantly, no device-related serious adverse events were reported in either group, and there were no deaths in either cohort.
These findings suggest that moving the procedure earlier in the treatment timeline did not appear to introduce new safety concerns within the parameters studied. For interventional physicians and PE response teams, that is an important point, because it indicates that the potential hemodynamic benefits of earlier clot removal may not come at the cost of a worsened acute safety profile.
Another procedural observation from the analysis also speaks to the performance of the device itself. Overall, repeat traversal of the right heart with the Symphony Thrombectomy System was required in only 4.6% of cases—five out of 109 procedures. Of those, two occurred in the early treatment group and three in the late group. Low rates of repeat traversal may be seen as a marker of procedural efficiency and device design, especially in a condition where minimizing time and complexity in the cath lab or interventional suite can be highly valuable.
Investigators Emphasize the Need for Randomized Trials
Commenting on the findings, lead author Sripal Bangalore, M.D., M.H.A., Professor in the Department of Medicine at NYU Grossman School of Medicine, noted that thrombectomy can be beneficial in intermediate-risk PE regardless of timing, but said the new data add to observational evidence suggesting that earlier catheter-based intervention may accelerate cardiac recovery.
According to Bangalore, the reductions seen in RV/LV ratio and mean pulmonary artery pressure support the concept that treating sooner after diagnosis may help reverse right heart strain more quickly. At the same time, he emphasized that randomized controlled trials are still needed to determine the optimal timing of thrombectomy and to clarify whether specific patient populations are more likely than others to benefit from earlier intervention.
That caution is important. Because the new report is a post-hoc analysis rather than a prospectively randomized comparison of early versus late treatment, its findings should be interpreted as hypothesis-generating rather than definitive. Post-hoc analyses can uncover clinically meaningful patterns, but they are not a substitute for trials specifically designed to test timing strategies head-to-head. Still, they often provide the rationale for the next wave of research—and in this case, the signal appears strong enough to fuel continued investigation.
Building on the SYMPHONY-PE Trial Foundation
The analysis draws on data from the SYMPHONY-PE Trial, Imperative Care’s investigational device exemption, or IDE, study conducted across 17 sites in the United States. That trial formed the basis for the U.S. Food and Drug Administration’s clearance of the Symphony Thrombectomy System for pulmonary embolism in August 2025. Results from the pivotal IDE trial were later published in the November 2025 issue of Circulation: Cardiovascular Interventions.
The SYMPHONY-PE study has therefore become the cornerstone of Imperative Care’s clinical evidence package for Symphony, supporting both regulatory clearance and ongoing physician education. The latest post-hoc analysis extends that evidence base by moving beyond the original primary endpoints and examining how treatment timing may shape outcomes.
For a company seeking to differentiate its thrombectomy platform in a competitive and rapidly evolving market, this kind of evidence generation is strategically important. Hospitals and physicians increasingly want not only proof that a device works, but also practical insight into how and when it should be used to achieve the best results. Studies like this one help build the clinical narrative around a device and can influence adoption patterns over time.
Commercial Momentum Builds as More Than 500 U.S. Patients Are Treated
Alongside the publication of the new analysis, Imperative Care announced that more than 500 pulmonary embolism patients in the United States have now been treated with the Symphony Thrombectomy System since its commercial launch in September 2025. The milestone signals meaningful physician uptake in less than a year on the market and suggests growing familiarity with the platform among interventional teams managing PE.
Imperative Care Chairman and Chief Executive Officer Fred Khosravi said the company set out to establish a new standard in PE treatment by developing a large-bore thrombectomy system designed to simplify decision-making, improve procedural efficiency, and allow physicians to focus more directly on patient care. He said the company is encouraged by the growing physician confidence in Symphony as well as by the continued accumulation of clinical evidence supporting the system’s safety profile and procedural performance.
Khosravi also acknowledged the broader human significance of the treatment milestone, emphasizing that behind every case is a patient and family affected by pulmonary embolism. He noted that the company is grateful to the physicians and patients who have placed their trust in the Symphony platform as part of efforts to deliver timely, potentially life-saving care.
Positioning Symphony in the Future of PE Intervention
The combination of fresh clinical data and commercial adoption gives Imperative Care additional momentum as it works to expand Symphony’s role in pulmonary embolism treatment. The new analysis does not settle the question of exactly when thrombectomy should be performed in intermediate-risk PE, but it strengthens the case that earlier intervention may offer meaningful physiological advantages—particularly in patients with higher-risk features—without compromising short-term safety.
If future randomized trials confirm these observations, the implications could be significant. Earlier thrombectomy could become more deeply integrated into PE response pathways, prompting hospitals to streamline diagnostic-to-treatment workflows and potentially intervene before right heart strain worsens. For device makers like Imperative Care, that would not only validate a treatment philosophy but also reinforce the value proposition of systems designed for efficient, decisive clot removal.
For now, Imperative Care appears to be making progress on two fronts at once: expanding the evidence base for Symphony and broadening real-world adoption of the technology. In a field where both clinical confidence and operational simplicity matter, the company’s latest announcements suggest that Symphony is gaining traction as physicians look for faster, safer, and more effective ways to treat patients with pulmonary embolism.
About the Symphony Thrombectomy System
The Symphony Thrombectomy System is a large-bore aspiration system designed to remove the guesswork from thrombectomy procedures, enabling more efficient, effective clot removal in patients with venous thromboembolism (VTE). Through real-time visualization inside the catheter and vessel, Symphony is designed to give physicians immediate insight into what is happening at every step of the procedure so they can make the right next move with confidence.
The system includes 16F and 24F catheters for smooth tracking, stability, and telescoping to reach distal anatomy; ProHelix® Mechanical Assist, designed to facilitate clot ingestion and avoid pulling a corked catheter across the heart when needed; the Symphony 24F Advance® Long Dilator for navigating through tortuous anatomy; and the Imperative Care Generator, a powerful aspiration pump.
For complete product information, including indications, contraindications, warnings, precautions and adverse events, visit: http://bit.ly/3pAaUlw.
About Imperative Care, Inc.
Imperative Care is a commercial-stage medical technology company focused on advancing treatments for patients suffering from thromboembolic disease, a serious medical condition caused by blood clot formation inside veins and arteries. Imperative Care was founded with the mission of bringing lifesaving treatments to patients suffering from ischemic stroke and other devastating vascular diseases caused by blood clot formation.
The company’s commercially available product portfolio includes the Zoom Stroke System, the Symphony Thrombectomy System and the Prodigy Thrombectomy System. In addition to our commercial products, we are developing the Telos robotic platform*, an endovascular robotic system designed to bring greater precision and standardization to procedures and expand access to lifesaving treatment. Imperative Care is based in Campbell, Calif.
