Reprogrammed streptokinases develop fibrin-targeting and dissolve blood clots with more potency than tissue plasminogen activator

BACKGROUND

Given the worldwide epidemic of cardiovascular diseases, a more effective means of dissolving thrombi that cause heart attacks, could markedly reduce death, disability and healthcare costs. Plasminogen activators (PAs) such as streptokinase (SK) and tissue plasminogen activator (TPA) are currently used to dissolve fibrin thrombi. SK is cheaper and more widely available, but it appears less effective because it lacks TPA's fibrin-targeted properties that focus plasminogen activation on the fibrin surface.

OBJECTIVE

We examined whether re-programming SK's mechanism of action would create PAs with greater fibrin-targeting and potency than TPA.

METHODS AND RESULTS

When fibrinogen consumption was measured in human plasma, reprogrammed molecules SKDelta1 and SKDelta59 were 5-fold and > 119-fold more fibrin-dependent than SK (P < 0.0001), and 2-fold and > 50-fold more fibrin-dependent than TPA (P < 0.001). The marked fibrin-targeting of SKDelta59 was due to the fact that: (i) it did not generate plasmin in plasma, (ii) it was rapidly inhibited by alpha2-antiplasmin, and (iii) it only processed fibrin-bound plasminogen. To assess the fibrin-targeting and therapeutic potential of these PAs in vivo, a novel 'humanized' fibrinolysis model was created by reconstituting plasminogen-deficient mice with human plasminogen. When compared with TPA, SKDelta1 and SKDelta59 were 4-fold (P < 0.0001) and 2-fold (P < 0.003) more potent at dissolving blood clots in vivo, respectively, on a mass-dose basis and 2-3 logs more potent than TPA (P < 0.0001) when doses were calibrated by standard activity assays.

CONCLUSION

These experiments suggest that reprogramming SK's mechanism of action markedly enhances fibrin-targeting and creates, in comparison with TPA, activators with greater fibrinolytic potency.

Platelet scintigraphy results of heparin versus streptokinase treatment in acute deep vein thrombosis

OBJECTIVE

The aim of the study was to document the therapeutic effects and primary recanalization ratios of either streptokinase or heparin in the therapeutic process of deep vein thrombosis (DVT). The results are obtained with the help of platelet scintigraphy.

DESIGN

The investigation was planned as a randomized, controlled and prospective study, including 20 patients within two groups. Group I contained 10 patients undergoing IV infusion therapy of unfractionated heparin while Group II contained 10 patients undergoing thrombolytic therapy using streptokinase. After 8 weeks, scintigraphies using Tc-99m HMPAO-labeled thrombocytes were made, and interpreted by two blinded nuclear medicine physicians. The results are compared using Mann-Whitney U- and chi2-tests.

RESULTS

No complication leading to interruption of therapy took place. Significantly smaller pathologic thrombocyte accumulations were detected in the streptokinase group. The difference was statistically significant (p = 0.019).

CONCLUSION

Although a general clinical improvement had been observed in all patients, the scintigraphic investigation showed that the thrombolytic therapy maintained a better deep vein luminous patency.

Near‐normal coronary angiography in a patient, who is entirely asymptomatic 24 years after successful intracoronary thrombolysis for ST elevation myocardial infarction. Follow‐up of the historically first Czech intracoronary thrombolysis patient

Extremely long-term follow-up (24 years) of the historically first Czech myocardial infarction patient, treated by intracoronary thrombolysis, is presented. His current coronary angiography confirmed the finding 24 years ago, that this was a case of smoking-induced thrombosis in otherwise healthy coronary arteries. Experience with 76 similar cases among 4093 consecutive coronary angiograms (including 778 done acutely for STEMI) is briefly described.

Blood clot disruption in vitro using shockwaves delivered by an extracorporeal generator after pre-exposure to lytic agent

The standard methods for recanalyzing thrombosed vessels are vascular stenting or administration of thrombolytic drugs. However, these methods suffer from uncertain success rate and side-effects. Therefore, minimally-invasive ultrasound methods have been investigated. In this article, we propose to use shockwaves after pre-exposure to fibrinolytic agent for disrupting thrombus. Shockwaves were delivered by an extracorporeal piezocomposite generator (120 mm in diameter, focused at 97 mm, pulse length = 1.4 micros). In vitro blood clots, made from human blood, were placed at the focal point of the generator. The clots were exposed to shockwaves either with or without prior immersion in a solution of streptokinase. The percentage of lysed clot was determined by weighing the clot before and after treatment. The proportion of lysed clot increased with the pressure at the focus and with the number of shocks. A mean clot reduction of 91% was obtained for 42 MPa in 4-min treatment duration only, without using streptokinase. For a treatment of 2 min at 29 MPa, the clot reduction increased significantly (p < 0.01) from 47% without streptokinase to 82% when streptokinase was used prior to shockwaves. These results also showed no significant damage to streptokinase due to exposure to shockwaves. This study suggests that extracorporeal shockwaves combined with streptokinase is a promising pharmaco-mechanical method for treating occlusive thrombus, and should be confirmed by in vivo trials. Additional studies must also be conducted with other fibrinolytic agents, whose abilities to penetrate clots are different.

Predictors of the outcome of thrombolytic therapy in prosthetic mitral valve thrombosis: a study of 62 events

BACKGROUND AND AIM OF THE STUDY

Treatment strategies and guidelines in the management of prosthetic valve thrombosis (PVT) remain controversial. The study aim was to assess the success and complication rate of thrombolytic therapy (TT) by comparing thrombus size, severity of symptoms, type of prosthetic valve, and time since valve implantation.

METHODS

Between April 1993 and December 2006, TT was administered for 62 thrombotic events in 55 patients with mitral PVT. Thrombus size was measured by planimetry, and its location and mobility assessed with transesophageal echocardiography (TEE). Continuous thrombolytic treatment in obstructive PVT (OPVT) was monitored using gradient measurement by transthoracic echocardiography every 2-5 h, and by visual assessment with TEE every 24 h.

RESULTS

All patients with non-obstructive PVT (NOPVT) were in NYHA class I or II. Among 52 patients with OPVT, eight were in NYHA class I or II, and 44 in NYHA class III-IV (p < 0.0001). The thrombus area (measured with TEE) before thrombolysis was < 0.8 cm2 in 24 cases, > or = 0.8 cm2 in 21 cases, and could not be measured in 17 events. Thrombolysis was successful in 45 events (73%) including all NOPVT. In 13 events (21%) the transvalvular gradient decreased but was not normalized. Thrombolysis failed in four events (6%). Complications of thrombolysis were present in 11 events (18%), and four patients died. There was no significant difference in the outcome of TT regarding the type of artificial valve, NYHA class or thrombus size. In cases of successful thrombolysis, the time since surgery was significantly shorter than in cases of partially successful or failed thrombolysis.

CONCLUSIONS

Based on previous data and the present findings, thrombolysis can be considered as first-line treatment in all patients with PVT, independent of the valve type, NYHA functional class, and thrombus size.

Pulmonary embolism: long-term follow-up after treatment with full-dose heparin, streptokinase or embolectomy

The study comprises 74 patients alive 30 days after the start of treatment of pulmonary embolism with heparin (n = 32), streptokinase (n = 22) or embolectomy (n = 20). The cumulative 5-year survival was 100% in the embolectomy group, compared to 75 +/- 7% (SE) in the medically treated patients (p less than 0.05). Cancer caused 78% of the late deaths. At follow-up 0.5-8.7 years after treatment the treatment groups were indistinguishable as regards right-sided heart catheterization data, pulmonary artery rest-obstruction, right ventricular diameter and wall thickness, ventilatory function and ECG changes. The embolectomized patients were in a more favourable NYHA classification level than the medically treated. Chronic pulmonary artery hypertension was found in 75% of patients with greater than or equal to 3 anamnestic recurrent embolic episodes before diagnosis compared to 8% of patients with less than or equal to 2 recurrent episodes (p less than 0.001). Patients with irreversible cardiocirculatory shock before embolectomy all had abnormal pulmonary vascular resistance (greater than 1.5 mmHg/l/min), depressed ventilatory function and more than 25% reduced pulmonary perfusion at follow-up. The major prognostic factors thus were cancer, the number of recurrent episodes and the degree of cardiocirculatory affection in the acute event. Although the embolectomized patients were the most affected initially, they had a good prognosis. This led us to extend our indications for embolectomy to include all patients with central emboli, irrespective of the degree of cardiocirculatory impairment.

Streptokinase treatment of deep venous thrombosis of the lower extremity. Clinical, phlebographic and plethysmographic evaluation of early and late results

The investigation comprises 19 patients with acute deep vein thrombosis of the leg treated with streptokinase. The acute clinical symptoms rapidly subsided in 15 patients. Phlebography, performed immediately after treatment, revealed complete thrombus regression in 7 cases, restoration of venous flow but remnants of thrombi in 4 and no effect in 7. One woman was not evaluated radiologically due to pregnancy. The phlebographic restoration seemed to be correlated to the duration of the thrombotic symptoms. Follow-up examinations 6-50 months after the thrombotic incident demonstrated normal phlebograms in 8 patients, all of whom were also free from post-thrombotic symptoms. Venous occlusion plethysmography confirmed that these patients had a normal venous outflow capacity and valvular function in the relevant limbs. By contrast, the remaining 11 patients, with more or less extensive remnants of thrombi at the follow-up phlebography, were found to have plethysmographic signs of venous obstruction and sometimes also valvular insufficiency. The results indicate that thrombolytic treatment is able to give a complete and lasting anatomical and functional restitution of the deep veins after an acute thrombosis in the leg, provided that treatment is induced early enough.

Long-term sequelae of calf vein thrombosis treated with heparin or low-dose streptokinase

A prospective randomized study was performed to investigate the long-term sequelae of calf vein thrombosis (CVT) and correlate them to the success of the initial treatment. Thirty-six patients with symptomatic CVT, verified by venography, were treated with heparin or low-dose streptokinase (SK) combined with low-dose heparin. Venography was repeated after 1 week, and long-term follow-up was performed clinically and with foot volumetry after an average of 5 years. Since the low-dose SK regimen led to serious hemorrhagic side-effects in a parallel study, the present investigation was discontinued prematurely. The thrombolysis achieved was greater with SK but, since the initial thrombi were somewhat larger in this group, no significant difference in the average size of the thrombi after therapy could be displayed between the groups. The long-term sequelae and results of foot volumetry were also equal. Signs or symptoms of venous insufficiency were found in 37%, and foot volumetry showed deep venous insufficiency in 26% of the cases. There was a correlation between the hemodynamic change, as assessed by foot volumetry, and the venographic severity. This relation was stronger for the size of the thrombus after treatment than for the initial size. Thus, it seems important to limit the extent of a CVT in order to minimize the long-term sequelae, but administration of SK is not justified due to side-effects.

Is streptokinase useful in the treatment of deep vein thrombosis?

Because of its fibrinolytic action, streptokinase is believed to reduce the severity of the postthrombotic syndrome in patients with deep vein thrombosis. A prospective and a retrospective study have been undertaken in an attempt to determine when this therapy is useful for patients with deep vein thrombosis. The prospective study included 15 patients with deep vein thrombosis: 5 were treated in the hospital with streptokinase and heparin and 5 only with heparin, 5 were treated at home with only phenprocoumon. All the patients received oral anticoagulant therapy for at least 6 months. Three to four months after the acute episode, phlebography and venous pressure measurements were carried out. Streptokinase appeared to give the best results but with more side-effects. In the retrospective study, 51 patients who had had deep vein thrombosis in 1969 were reexamined 31-47 months later. It was found that more than 50% of the patients with a thrombosis in the femoral and/or iliac vein developed a severe postthrombotic syndrome, in contrast to only 9% of those with a thrombosis in the popliteal vein or lower. It is recommended, on the basis of both the prospective and the retrospective study, that patients with a thrombosis in the femoral and/or iliac vein should be treated with either heparin or streptokinase during the early stage. It is probable that streptokinase will significantly decrease the frequency and severity of the postthrombotic syndrome in these patients in particular, although this has not yet been proven.

Comparison of streptokinase with heparin: late results in the treatment of deep venous thrombosis

Nineteen cases were reinvestigated 8-14 years after treatment with SK or heparin. Judging from personal interviews, foot volumometry and phlebography, treatment with SK appears to be more preferable since it was less often followed by late severe postthrombotic changes.

Streptokinase therapy in the routine management of deep venous thrombosis in the lower extremities. A retrospective study of phlebographic results and therapeutic complications

One hundred and eight patients with phlebographically verified deep venous thrombosis were treated with streptokinase. Total or partial thrombolysis was phlebographically demonstrated in 60 patients (55.6%). Three patients died during treatment, all from pulmonary embolism. Six patients developed clinical signs suggestive of pulmonary embolism. In 16 patients (14.8%), major bleeding complicated the treatment. One patient had anaphylactic shock, while various allergic reactions were recorded in 22. Streptokinase therapy in the routine management of deep venous thrombosis carries an acceptable efficacy and safety similar to what has been achieved under research conditions.

Rapid thrombolysis and preservation of valvular venous function in high deep vein thrombosis. A comparative study between streptokinase and heparin therapy

The results of streptokinase and heparin treatment are compared in a 4-year prospective study with special reference to preservation of high valvular venous function. An objective assessment was based upon phlebographic examinations before, during and 1-2 months after therapy. Complete lysis was demonstrated in 44% of high thromboses treated with streptokinase and in 6% treated with heparin. Retrograde phlebography revealed normal function of the proximal femoral valves in 92% of streptokinase-treated high thromboses, compared with 13% of those treated with heparin. These phlebographic results were considered to be a valid prognostic indicator of the eventual development of the postthrombotic syndrome. Allergic reactions were seen in 39% and minor haemorrhagic complications in 18% of the streptokinase-treated cases. The therapeutic benefit of streptokinase therapy in this study was found to outweigh any disadvantages incurred by observed complications.

A prospective study of streptokinase and heparin in the treatment of deep vein thrombosis

In a prospective trial, 42 medical patients with a history of deep vein thrombosis of less than five days were allocated at random to treatment with streptokinase or heparin. Only patients with extensive thromboses were included. Streptokinase was given in a loading dose of 250 000 IU and a maintenance dose of 100 000 IU/hour for 4 days as a mean. Heparin was given in a loading dose of 15 000 IU and a maintenance dose of 20 000-50 000 IU/day. The therapeutic results were evaluated by phlebography. Significant thrombolysis occurred in 71.4% of 21 patients treated with streptokinase and in 23.8% of the 21 heparin-treated patients. Using the chi2-test for overall association, this difference was statistically highly significant (p = 0.002). Three patients in each treatment group experienced major bleeding, two in each group requiring blood transfusions. Minor bleeding and slight rise in temperature were encountered more often in the streptokinase than in the heparin group. It is concluded that patients with acute deep vein thrombosis with proximal extension of the thrombus beyond the calf veins should be offered a therapeutic trial with streptokinase.

A controlled clinical trial of streptokinase and heparin in the treatment of major pulmonary embolism

Treatment with streptokinase or heparin was allocated randomly to 20 patients with major pulmonary embolism verified by angiography. In addition, 4 patients treated with streptokinase and 1 patient treated with heparin were included in the trial prior to the start of treatment. Streptokinase of heparin was given for 72 hours and pulmonary angiography was repeated. The angiographic evidence of thrombolysis was significantly greater (p less than 0.01) in the 14 patients treated with streptokinase than in the 11 treated with heparin. In the heparin group, 1 patient died from massive embolism 15 hours after the start of treatment. In another patient who died 4 weeks later from cerebral glibolastoma, persistent massive embolism contributed to the fatal outcome. In the streptokinase group, 1 patient with a metastatic pulmonary carcinoma died 3 weeks after the start of treatment from gangrene of both legs following thrombotic occlusion of the inferior vena cava. Bleeding was more common after treatment with streptokinase than with heparin, but was not a serious problem in any patient. It is concluded that patients with life-threatening pulmonary embolism should be offered the benefits of streptokinase.

Pulmonary hypertension in patient with elevated homocystein level and blast injuries

38-year-old man had chronic deep venous thrombosis (DVT) as a result of multiple injuries caused by an explosion of grenade 12 years ago, with recurrent pulmonary thromboembolisms and pulmonary hypertension which was unrecognized for a decade. Patient was admitted with a progressive dyspnea and exercise intolerance (NYHA II). The diagnosis was established according to clinical symptoms, transthoracic echocardiography, phlebography, lung scintigraphy and pulmonary angiography. Oral anticoagulant therapy was introduced and cava filter indicated to implant. During phlebography a floating thrombus was found in the inferior cava vein underneath renal vein. Implantation was delayed and patient received systemic fibrinolytic therapy with streptokinase (7500 000 UI within 4 days), followed by heparin infusion and warfarin. Post-fibrinolytic phlebography showed clear lumen of inferior vena cava. Fibrinolysis had also affected pulmonary hypertension-systolic pressure in the right ventricle measured by Doppler echocardiography decreased from 90 to 65 mmHg. Permanent intravenous cava filter was implanted.

Rapid myoglobin analysis to assess coronary artery reperfusion after acute myocardial infarction

BACKGROUND

Coronary artery reperfusion significantly improves outcome in patients with acute myocardial infarction. A noninvasive method for assessing reperfusion in the early stage of infarction should be helpful in patient management.

HYPOTHESIS

We sought to assess whether release pattern of myoglobin is helpful in identifying patients with and without reperfusion following thrombolytic therapy for myocardial infarction.

METHODS

Myoglobin was measured before thrombolysis, half hourly for 4 h, then every 2 h for 10 h. Myoglobin was analyzed using a ward-based "rapid" and automated analyzer that yielded quantitative results within 10 min of blood collection.

RESULTS

In the 15 patients with coronary reperfusion, the time from thrombolysis to peak myoglobin levels (mean +/- SD, 2.4 +/- 1.5 h) was significantly lower than in nonreperfused patients (5.1 +/- 2.9, p < 0.01). As an indicator for reperfusion, a doubling of myoglobin 1 h after streptokinase achieved a sensitivity of 80%, a specificity of 80%, and a predictive accuracy of 80%.

CONCLUSIONS

The difference in myoglobin release kinetics is useful in identifying patients without coronary reperfusion and should aid in their management.

Influence of thrombolytic therapy on the incidence of left ventricular thrombi after acute anterior myocardial infarction: role of successful reperfusion

BACKGROUND

Previous studies have reported controversial results regarding the effectiveness of systemic thrombolysis in preventing left ventricular (LV) thrombus after acute myocardial infarction (MI).

HYPOTHESIS

This study was performed to evaluate the influences of thrombolysis, and particularly successful reperfusion, on the incidence of LV thrombus formation after acute anterior MI.

METHODS

In all, 191 patients suffering from a first attack of acute anterior MI were prospectively evaluated by two-dimensional echocardiography and coronary angiography, performed at the end of the first week and within the first two weeks of MI, respectively. Of these, 98 who presented within 12 h of onset of symptoms received intravenous streptokinase (1.5 million IU), while the remaining 93 patients who, either because of contraindications or late admission, did not receive thrombolytic treatment served as control group. All patients received aspirin and full-dose anticoagulation with intravenous heparin. Successful reperfusion in the streptokinase group was assessed by enzymatic and electrocardiographic evidence.

RESULTS

The overall incidence of LV thrombi was 24.6% (47/191). When all patients were evaluated, no statistically significant difference was found between the frequency of LV thrombi in the patients who had thrombolysis (22.4%) and those who did not (26.8%), despite a trend toward the formation of fewer thrombi in the initial group (p > 0.05). However, the patients who had successful reperfusion with streptokinase (n = 64) had significantly reduced incidence of LV thrombi compared with those who did not receive thrombolytic therapy (20 vs. 26.8%, p < 0.05). Stepwise multivariate analysis suggested that LV abnormal wall motion score (p = 0.01) and presence of LV aneurysm were independent predictors of LV thrombus formation in patients with acute anterior MI.

CONCLUSION

Not all patients who received streptokinase for acute anterior MI, but only those with successful reperfusion had reduced incidence of LV thrombi. The favorable effects of thrombolysis on LV thrombus formation are probably due to the preservation of global LV systolic function.

Thrombolytic therapy guided by a decision analysis model: are there potential benefits for patient management?

BACKGROUND

Although thrombolytic therapy improves the outcome of myocardial infarction, it is associated with increased risks of stroke and bleeding; these risks may outweigh the benefits of therapy. The risks and benefits of thrombolysis, for any individual clinical situation, can be explicitly estimated by means of decision analysis.

HYPOTHESIS

The aim of this study was to compare the actual use of thrombolytic agents for suspected acute myocardial infarction (AMI) with the management preferred by a decision analysis model.

METHODS

Admission data prospectively obtained in 262 consecutive patients admitted to a rural community hospital's coronary care unit with suspected AMI, as well as clinical decisions and outcomes, were reviewed and analyzed.

RESULTS

Seventeen deaths from AMI and no major strokes were observed, compared with 18.30 deaths and 0.85 major strokes predicted by a decision analysis model. Forty-seven of 84 patients with confirmed AMI and 3 of 178 without AMI were given a thrombolytic agent, compared with 65 patients with and 7 without AMI who had decision analysis-guided therapy. Decision analysis-guided therapy could have saved 3.7 additional lives and gained 29.6 life years, but produced 0.4 extra strokes. Changing the quality adjustment for stroke or heart failure would not have altered the treatment preferred by decision analysis in any of the 262 cases studied. Some patients were predicted to benefit considerably from thrombolysis with little extra risk of stroke and vice versa: all cases must, therefore, be assessed individually.

CONCLUSIONS

A decision analysis model can guide thrombolytic therapy by promptly defining its risks and benefits.

Preinfarction angina prevents left ventricular remodeling in patients treated with thrombolysis for myocardial infarction

BACKGROUND

It has been shown that preinfarction angina may have beneficial effects on infarct size and mortality. However, there are no studies that have serially assessed the impact of preinfarction angina on left ventricular (LV) function in a large series of patients.

HYPOTHESIS

The study was undertaken to determine whether preinfarction angina (within 7 days before infarction) influences LV remodeling.

METHODS

In all, 119 consecutive patients with acute myocardial infarction were serially evaluated by 2-dimensional echocardiography (on Days 1, 2, 3, and 7; at 3 and 6 weeks; and at 3, 6, and 12 months following infarction). Left ventricular volumes were determined using Simpson's biplane formula and normalized for body surface area. Wall motion score index and sphericity index were calculated for each study. Coronary angiography was performed before discharge.

RESULTS

Preinfarction angina was detected in 39 of 119 patients. Initial echocardiographic and clinical data as well as the incidence of patent infarct-related artery and collaterals were similar for patients with and without preinfarction angina. In the subset of thrombolysed patients, patients with preinfarction angina showed decrease of LV end-diastolic and end-systolic volumes during the follow-up period (p = 0.033 and p = 0.001, respectively), and improvement of wall motion score index (p < 0.001) and ejection fraction occurred (p = 0.001), without changing of LV shape (p > 0.05); in addition, patients with preinfarction angina had smaller LV volumes and higher ejection fraction than did those without angina, from 3 weeks onward. These favorable effects were not detected in patients not treated with thrombolysis.

CONCLUSIONS

These data indicate that preinfarction angina has an inhibiting effect on long-term LV remodeling in patients who underwent thrombolysis for first acute myocardial infarction. It appears that preinfarction angina has no impact on infarct size and early postinfarction LV function.