Case Presentation: A 82-year-old male patient with a past medical history of Coronary Artery Bypass Graft (CABG) and severe mitral regurgitation with repair presented at 6 weeks after bioprosthetic mitral valve replacement with a two-day history of sudden onset of dyspnea, that was associated with exertion and orthopnea. Vitals upon evaluation were as follows: Initial blood pressure was 106/59 mm Hg which later trended down to 77/45 mm Hg, with heart rate of 100 bpm and respiratory rate of 24 cpm. Cardiovascular examination was normal with no evidence of jugular venous distention. The pulmonary examination was remarkable for bibasilar rales. Upon further evaluation, patient was noted to have elevated Beta Natriuretic Peptide (BNP) at 992 pg/ml (normal: 0-100 pg/ml), Troponin I: 0.21 ng/ml (normal: 0-0.03 ng/ml). A portable chest x-ray revealed small left-sided pleural effusion with an increase in interstitial markings suspicious for interstitial edema. The patient was diagnosed with acute on chronic congestive heart failure. He was started on intravenous furosemide and dopamine drip. Transesophageal Echocardiogram (TEE) revealed well seated Edwards bio-prosthetic mitral valve. Also noted was a thrombus on a frozen and immobile mitral valve leaflet, associated with severe mitral valvular stenosis and mitral regurgitation. The left atrium was moderately dilated. Left ventricle (LV) was normal in size but LV Ejection Fraction (EF) was low normal at 50%. Mean gradient across the prosthetic mitral valve was high at 23 mm Hg. The patient was subsequently started on a low dose (25 mg) slow infusion (6 hours) of intravenous tissue Plasminogen Activator (tPA, alteplase) infusion. The dose was repeated for another six hours. TEE was repeated post infusion. There was no evidence of thrombus and all mitral valvular leaflets were completely mobile with no residual mitral stenosis or regurgitation. The patient showed dramatic improvement in his symptoms. Mean gradient was down to 8 mm Hg on repeat TEE. The patient was subsequently started on warfarin bridged with heparin intravenous infusion.
Discussion: Most of the available data pertaining to the treatment of prosthetic valve thrombosis are available for mechanical valve prosthesis [1, 2]. Data is very limited with respect to the management of bioprosthetic valve thrombosis (BPVT), attributed to its apparent rare events . Thrombolysis is an established first-line therapy for high-risk patients with mechanical valve thrombosis. However, its use in BPVT is still a matter of debate [3-5]. Anticoagulation and operative interventions are the mainstays of treatment in BPVT. This case demonstrates the efficacy of thrombolytics in an obstructive BPVT. We believe tPA mediated thrombolysis is a reasonable treatment option in BPVT before considering surgery and can significantly reduce the burden on the patient and health care costs involved in surgical valvular replacement.
Conclusions: Thrombolysis using tPA is safe and effective treatment option in BPVT and should be considered before surgery. This can significantly reduce the burden on the patient and health care costs involved in surgical replacement of a thrombosed valve. However, there are no randomized controlled studies comparing these two modalities of treatment.