Time to Thrombolysis in Left-sided Prosthetic Valve Thrombosis: Reaffirming the Critical Window

To the Editor, We read with great interest the article by Kayal et al.,1“Time to Thrombolysis and Outcomes in Patients with Left-sided Prosthetic Valve Thrombosis: Is Thrombolysis Worth Beyond 7 Days?” (Heart Views 2025;26:96-101), which addresses the important question of whether delayed therapy retains efficacy. The study’s finding that early thrombolysis (≤7 days) yields superior outcomes reinforces the importance of prompt recognition and intervention, particularly in settings where surgical options may be limited. Nevertheless, several methodological aspects merit consideration. First, as an observational study, potential selection bias cannot be excluded; patients treated earlier may have presented with smaller thrombi, more recent onset, or better hemodynamic profiles. Second, defining the exact onset of symptoms in prosthetic valve thrombosis (PVT) is inherently imprecise, and the 7-day threshold – though practical – may not accurately reflect thrombus biology. As thrombi evolve from fresh to organized structures, fibrinolytic penetration and efficacy diminish progressively rather than abruptly. Third, heterogeneity in thrombolytic agents and infusion protocols complicates the interpretation of efficacy and safety, particularly when most patients received streptokinase. Variations in infusion duration or dosage may have influenced outcomes, including bleeding rates. Drawing on several decades of clinical experience in a cardiovascular specialized tertiary center managing patients with PVT, including our own prospective series, we evaluated patients with left- and right-sided PVT using a standardized streptokinase regimen (loading dose followed by continuous infusion for up to 72 h or until valve function normalized). Despite a mean delay of approximately 10 days from symptom onset, high complete response rates were achieved with acceptable bleeding risk.2 These studies represented early systematic experiences using thrombolysis as first-line therapy in a substantial number of patients. The favorable results with prolonged, low-intensity infusion demonstrated that effective and safe thrombolysis was feasible even beyond the 1st week, providing a foundation for subsequent evaluation of alternative agents. Building on this evidence, other authors highlighted that thrombolytic success depends primarily on thrombus size, mobility, and hemodynamic impact rather than on a strict temporal cutoff. They advocated for early yet individualized intervention, guided by both echocardiographic findings and the patient’s overall clinical stability.3,4 Current guidelines endorse a patient-specific, multidisciplinary approach to PVT. Thrombolysis remains an acceptable first-line therapy in obstructive left-sided PVT when surgical risk is prohibitive or expertise is limited, provided that standardized, low-dose protocols and echocardiographic monitoring are applied.5 From a practical standpoint, the study reinforces that “time matters” in PVT management; however, therapeutic success is not exclusively time-dependent. In selected patients – particularly in resource-limited settings or when surgery is unavailable – carefully monitored thrombolysis beyond 7 days may still be justified when imaging suggests organized but hemodynamically significant thrombus. Ultimately, individualized, echocardiography-guided decision-making should prevail over rigid temporal thresholds. In conclusion, early thrombolysis is supported, but late therapy should not be precluded when clinically indicated. Future multicenter, protocol-driven studies are warranted to refine the optimal timing, dosage, and agent selection for left-sided PVT. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.