Thrombi lysis with STK for struck valve
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Thrombolysis with Streptokinase (STK) for Stuck Prosthetic Heart Valve (Prosthetic Valve Thrombosis - PVT)
Background
Prosthetic valve thrombosis (PVT) is a life-threatening complication of mechanical heart valve (MHV) replacement. The annual incidence ranges from 0.1% to 5.7%, with higher rates seen in:
- Mitral and tricuspid positions (vs. aortic)
- Early perioperative period
- Caged-ball prostheses (older designs)
- Sub-therapeutic anticoagulation (most common cause)
PVT causes valve obstruction ("stuck valve") via thrombus formation on or around the leaflets, impairing their motion.
- Fuster and Hurst's The Heart, 15th Ed.
Diagnosis
Before thrombolysis, confirm PVT with multimodality imaging:
| Modality | Finding |
|---|---|
| TTE/TEE | Elevated transvalvular gradient, reduced leaflet excursion, visible thrombus |
| Cine-fluoroscopy | Reduced/absent leaflet motion (especially for mechanical valves) |
| CT (MDCT) | Hypo-attenuating leaflet thickening; best for TAVR/bioprosthetic SLT |
| 3D-TEE | Planimetry of valve area |
Indications for Thrombolytic Therapy with STK
Thrombolysis is indicated when:
- Obstructive PVT with high surgical risk or surgery unavailable
- Right-sided valve thrombosis (tricuspid/pulmonary) - preferred over surgery
- Non-obstructive PVT not responding to optimised anticoagulation
- Left-sided valve thrombosis in hemodynamically stable patients at high surgical risk
Preferred over surgery for right-sided valves - the embolic risk of thrombolysis to the pulmonary vasculature is far less consequential than systemic embolism.
STK Dosing Regimens
Streptokinase is one of three fibrinolytics used for PVT (alongside tPA and urokinase). Classic STK regimens include:
| Regimen | Dose | Duration |
|---|---|---|
| Standard | 250,000 IU loading over 30 min, then 100,000 IU/hr | 12-72 hours (until success or complication) |
| Slow infusion | 500,000 IU over 6 hours | Repeated sessions if needed |
| Low-dose (alternative) | 1,500,000 IU over 6 hours | Single or repeated sessions |
Note: STK is antigenic, so pre-treatment with hydrocortisone 100 mg IV and antihistamine is recommended to prevent allergic reactions. STK cannot be readministered within 6-12 months due to neutralising antibodies.
Heparin is withheld during STK infusion and restarted when aPTT falls to <80 seconds after completion.
Success Rates and Complications
HATTUSHA Study (JACC 2022, n=158 obstructive PVT) - Key Data:
- Used slow/ultraslow low-dose t-PA (not STK), but provides reference benchmarks
- TT success rate: 90.4%
- 3-month mortality with TT: 2.4% vs surgery 18.7%
- Major complications TT: 6% vs surgery 41.3%
Historical STK data:
| Outcome | Rate |
|---|---|
| Complete lysis success | ~70-80% |
| Systemic embolism | ~10-15% |
| Stroke | ~5% |
| Major bleeding | ~5% |
| Death | ~5-10% |
Monitoring During STK Infusion
- Echocardiography (TTE/TEE) every 6-12 hours to assess lysis progress
- Fluoroscopy to confirm restored leaflet mobility
- aPTT, fibrinogen levels (target fibrinogen >1 g/L to detect over-fibrinolysis)
- Clinical monitoring for signs of embolism, bleeding
Endpoint of thrombolysis: normalisation of transvalvular gradients + restored full leaflet excursion on imaging
Contraindications to STK/Thrombolysis
| Absolute | Relative |
|---|---|
| Active internal bleeding | Recent surgery (<2 weeks) |
| Recent stroke (<2 months) | Severe hypertension |
| Intracranial neoplasm | Infective endocarditis |
| Prior STK within 6-12 months | Pregnancy |
| Large mobile thrombus (>10mm) | Left-sided obstructive PVT + hemodynamic instability (→ surgery preferred) |
Current Guideline Positions (ESC vs. ACC/AHA)
| Scenario | ESC Recommendation | ACC/AHA Recommendation |
|---|---|---|
| Obstructive PVT, hemodynamically unstable | Emergency surgery (Class I) | Urgent surgery |
| Obstructive PVT, stable, high surgical risk | Thrombolysis (Class IIa) | Thrombolysis reasonable |
| Right-sided PVT | Thrombolysis preferred | Thrombolysis preferred |
| Non-obstructive PVT | Optimise anticoagulation first; thrombolysis if persists | Similar |
Fuster and Hurst's The Heart, 15th Ed., Table 29-4
Algorithm: Management of Stuck Valve (PVT)
Suspected PVT
↓
Multimodality imaging (TTE/TEE + fluoroscopy ± CT)
↓
Obstructive?
├── YES → Hemodynamically UNSTABLE?
│ ├── YES → Emergency SURGERY (Class I)
│ └── NO → High surgical risk?
│ ├── YES → THROMBOLYSIS (STK or tPA)
│ └── NO → SURGERY preferred
└── NO (non-obstructive) → Optimise anticoagulation (UFH bridge → increase VKA target)
If thrombus persists → Thrombolysis
STK vs. Other Thrombolytics
| Agent | Advantages | Disadvantages |
|---|---|---|
| Streptokinase | Cheapest; widely available in low/middle-income countries | Antigenic; cannot repeat within 6-12 months; slow infusion needed |
| tPA (alteplase) | Non-antigenic; can be repeated; low-dose slow regimens have better safety profile | More expensive |
| Urokinase | Non-antigenic; direct activator | Less widely available |
Current evidence favours slow/ultraslow low-dose tPA over STK for better safety (fewer embolic events), but STK remains an acceptable alternative where tPA is unavailable or cost is prohibitive.
Recent Evidence
- HATTUSHA Study (Ozkan et al., JACC 2022, PMID 35272803): Prospective multicenter study showing TT (low-dose slow t-PA) has ~90% success and far lower mortality (2.4%) than surgery (18.7%) for obstructive PVT.
- Soria Jimenez et al. (JACC 2023, PMID 37225366): JACC review confirms multimodality imaging-guided thrombolysis as a first-line option in high surgical risk patients; transcatheter leaflet manipulation emerging for contraindications to TT.
- Serban et al. (Trends Cardiovasc Med 2024, PMID 37499958): Comprehensive guideline comparison; highlights ESC-ACC/AHA differences and proposes pragmatic algorithm combining both.
Recent evidence note: Modern practice increasingly favours low-dose slow tPA over STK for PVT due to better safety data. If STK is used, the slow/ultraslow infusion protocol is strongly preferred over bolus administration to minimise embolic complications.
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