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

Diagnostic evaluation and management of chronic thromboembolic pulmonary hypertension: a clinical practice guideline

BACKGROUND

Pulmonary embolism is a common condition. Some patients subsequently develop chronic thromboembolic pulmonary hypertension (CTEPH). Many care gaps exist in the diagnosis and management of CTEPH patients including lack of awareness, incomplete diagnostic assessment, and inconsistent use of surgical and medical therapies.

METHODS

A representative interdisciplinary panel of medical experts undertook a formal clinical practice guideline development process. A total of 20 key clinical issues were defined according to the patient population, intervention, comparator, outcome (PICO) approach. The panel performed an evidence-based, systematic, literature review, assessed and graded the relevant evidence, and made 26 recommendations.

RESULTS

Asymptomatic patients postpulmonary embolism should not be screened for CTEPH. In patients with pulmonary hypertension, the possibility of CTEPH should be routinely evaluated with initial ventilation/perfusion lung scanning, not computed tomography angiography. Pulmonary endarterectomy surgery is the treatment of choice in patients with surgically accessible CTEPH, and may also be effective in CTEPH patients with disease in more 'distal' pulmonary arteries. The anatomical extent of CTEPH for surgical pulmonary endarterectomy is best assessed by contrast pulmonary angiography, although positive computed tomography angiography may be acceptable. Novel medications indicated for the treatment of pulmonary hypertension may be effective for selected CTEPH patients.

CONCLUSIONS

The present guideline requires formal dissemination to relevant target user groups, the development of tools for implementation into routine clinical practice and formal evaluation of the impact of the guideline on the quality of care of CTEPH patients. Moreover, the guideline will be updated periodically to reflect new evidence or clinical approaches.

Incidence of arterial cardiovascular events after venous thromboembolism: a systematic review and a meta-analysis

SUMMARY BACKGROUND

Whether patients with unprovoked venous thromboembolism (VTE) have a higher risk of arterial cardiovascular events than the general population and patients with provoked VTE is a matter of debate.

OBJECTIVE

To perform a systematic review and a meta-analysis aimed at assessing the risk of arterial cardiovascular events in patients with unprovoked VTE as compared with both patients with provoked VTE and controls.

METHODS

A systematic search was performed. Studies reporting on (i) patients with confirmed VTE, (ii) a follow-up of at least 6 months and (iii) the incidence of arterial cardiovascular events (acute myocardial infarction and ischemic stroke) were included in the systematic review. Those studies reporting separate incidences of cardiovascular events in patients with unprovoked and provoked VTE or patients with unprovoked VTE and controls were included in the incidence rate meta-analysis.

RESULTS

Overall, 17 studies were included in the systematic review. The weighted mean incidence of arterial cardiovascular events was 0.46% [95% confidence interval (CI) 0.34-0.59] and 0.35% (95% CI 0.24-0.49) per patient-year in patients with unprovoked and provoked VTE, respectively. Six studies were included in the meta-analysis. The risk of arterial cardiovascular events appeared to be higher in patients with unprovoked VTE than in controls [incidence rate ratio (IRR) 1.87, 95% CI 1.32-2.65] and than in patients with provoked VTE (IRR 1.86, 95% CI 1.19-2.89).

CONCLUSIONS

Patients with unprovoked VTE have a higher risk of arterial cardiovascular events than patients with provoked VTE over long-term follow-up.

Major pulmonary embolism: review of a pathophysiologic approach to the golden hour of hemodynamically significant pulmonary embolism

Major pulmonary embolism (PE) results whenever the combination of embolism size and underlying cardiopulmonary status interact to produce hemodynamic instability. Physical findings and standard data crudely estimate the severity of the embolic event in patients without prior cardiopulmonary disease (CPD) but are unreliable indicators in patients with prior CPD. In either case, the presence of shock defines a threefold to sevenfold increase in mortality, with a majority of deaths occurring within 1 h of presentation. A rapid integration of historical information and physical findings with readily available laboratory data and a structured physiologic approach to diagnosis and resuscitation are necessary for optimal therapeutics in this "golden hour." Echocardiography is ideal because it is transportable, and is capable of differentiating shock states and recognizing the characteristic features of PE. Spiral CT scanning is evolving to replace angiography as a confirmatory study in this population. Thrombolytic therapy is acknowledged as the treatment of choice, with embolectomy reserved for those in whom thrombolysis is contraindicated.

Emergency department management of pulmonary embolism

There are several points that bear repetition. First, consider the diagnosis of PE in all patients presenting with chest pain, dyspnea, syncope, oxygen desaturation, or unexplained hypotension. Evaluate these patients in a rational manner. At any individual hospital, develop algorithms with consultants so that when one is faced with a patient with a PE, the flow of both diagnostics and therapeutics flows smoothly and rapidly. Consider the concept of risk stratification, and remember that not all patients with PE are created equal. In particular, be on the same page with all consultants regarding the use of right heart echocardiography, both for its potential diagnostic capabilities and for its ability to identify patients who could be at greater risk for bad outcomes.

Thrombolytic therapy of pulmonary embolism: a comprehensive review of current evidence

Pulmonary embolism (PE) is a common disorder that is accompanied by significant morbidity and mortality. Although anticoagulation is the standard treatment for PE, thrombolytic therapy, with its ability to produce rapid clot lysis, has long been considered an attractive alternative. Although many studies have been performed over the past three decades, however, the indications for the use of thrombolytic agents in patients with PE remain controversial. In this article, we review the medical literature and provide evidence-based guidelines for the use of thrombolytic therapy. We will also discuss the practical aspects of PE thrombolysis.

Thrombolytic therapy for venous thrombosis and pulmonary embolism

Streptokinase, urokinase, tissue plasminogen activator and similar drugs can all cause lysis of venous thrombi and pulmonary emboli, but there is small evidence that accelerated lysis achieves a significantly better clinical outcome, on average, in the shorter or longer term, than heparin alone. Thrombolytic therapy for deep leg vein thrombosis aims to restore flow and to preserve venous valves, and so to prevent chronic post-phlebitic disability, but no trial has convincingly demonstrated that the last can be achieved in more than a few patients. Only a small minority of people with extensive proximal thrombosis develop disabling post-phlebitic venous insufficiency, and there are no good clinical predictors of this outcome. As a result, any widespread use of thrombolytics would bring an immediate risk of major bleeding to many people who will never be destined to develop a clinically important problem. Thrombolytic therapy after venous thrombosis should be avoided except, perhaps, in a few carefully selected patients with severe obstruction. The case for using thrombolytics after recent pulmonary embolism is strongest in the limited number of patients with ongoing hypoxia, respiratory distress, pulmonary hypertension and right heart failure, because thrombolytic therapy often achieves an impressive and almost immediate clinical benefit in this clinical setting. Whether early relief from pulmonary artery obstruction translates into longer-term advantage over heparin remains uncertain, however, because no comparative trial has ever shown these drugs to reduce mortality after pulmonary embolism. In all cases, both the physician and the patient must balance the certainty of an immediate bleeding risk against the uncertainty of a better than marginal real benefit.

Comparative efficacy of a two-hour regimen of streptokinase versus alteplase in acute massive pulmonary embolism: immediate clinical and hemodynamic outcome and one-year follow-up

OBJECTIVES

This study sought to compare the efficacy of 2-h regimens of alteplase and streptokinase in acute massive pulmonary embolism. The primary end point was immediate hemodynamic improvement, and secondary end points included early clinical efficacy and safety, as well as 1-year clinical outcome.

BACKGROUND

Several thrombolytic regimens have been compared for the past 10 years in randomized studies, showing that 2-h infusion regimens of alteplase or urokinase lead to faster hemodynamic improvement than former 12- to 24-h administration protocols in acute massive pulmonary embolism. Many trials have focused on immediate hemodynamic and angiographic outcomes, but none has addressed long-term follow-up after thrombolysis.

METHODS

Sixty-six patients with acute massive pulmonary embolism (Miller score > 17 and mean pulmonary artery pressure >20 mm Hg) were randomly assigned to receive either a 100-mg 2-h infusion of alteplase (n = 23) or 1.5 million IU of streptokinase over 2 h (n = 43). In both groups, heparin infusion was started at the end of thrombolytic infusion and adapted thereafter. Total pulmonary resistance was monitored over a 12-h period. Pulmonary vascular obstruction was assessed 36 to 48 h after thrombolytic therapy. One-year follow-up information included death, cause of death, recurrent pulmonary embolism, chronic thromboembolic pulmonary hypertension, stroke and bleeding.

RESULTS

Both groups had similar baseline angiographic and hemodynamic characteristics of severity, with maintained cardiac output in 64 (97%) of 66 patients. The results (mean +/- SD) demonstrated that despite a faster total pulmonary resistance improvement observed at 1 h in the alteplase group compared with the streptokinase group (33+/-16% vs. 19 16%, p = 0.006), a similar hemodynamic efficacy was obtained at 2 h when both thrombolytic regimens were completed (38+/-18% vs. 31+/-19%). There was no significant difference in either pulmonary vascular obstruction at 36 to 48 h or bleeding complication rates. One-year event-free survival was similar in both groups, as most events were related to concomitant diseases.

CONCLUSIONS

These results suggest that a 2-h regimen of streptokinase can be routinely used in patients with massive pulmonary embolism and maintained cardiac output without obviously compromising efficacy or safety.

Association between right ventricular function and perfusion abnormalities in hemodynamically stable patients with acute pulmonary embolism

BACKGROUND/OBJECTIVES

Patients presenting with acute pulmonary embolism associated with hemodynamic compromise exhibit right ventricular enlargement and dysfunction on transthoracic echocardiogram. However, the degree of echocardiographic abnormalities among hemodynamically stable patients without preexisting cardiopulmonary disease during the acute stage of pulmonary embolism, and following treatment, is unknown. Therefore, this study was designed to assess the extent of right ventricular abnormalities detected on transthoracic echocardiogram in patients following acute pulmonary embolism and during treatment with anticoagulation or vena caval interruption. The extent of pulmonary vascular obstruction and complication rate on follow-up were also assessed.

DESIGN/INTERVENTIONS

Sixty-four consecutive hemodynamically stable patients without preexisting known cardiopulmonary disorder presenting with acute pulmonary embolism and undergoing treatment with anticoagulation or inferior vena caval interruption were studied. All subjects underwent a two-dimensional transthoracic echocardiogram within 24 h of diagnosis. The degree of perfusion abnormality on lung scan was quantified. Twenty-six patients underwent follow-up echocardiogram and lung scan at 6 weeks. The echocardiographic findings were compared with those obtained from a group of normal control subjects matched for gender and age.

RESULTS

Although the mean right ventricular end-diastolic areas did not differ (21.9+/-5.2 cm2 vs 20.1+/-2.9 cm2 for control subjects; p=not significant), the right ventricular end-systolic area was larger in comparison to our series of control subjects (14.6+/-5.1 cm2 vs 11.7+/-2.0 cm2; p=0.025). Fractional right ventricular area change was reduced in the patient group compared with the control subjects (34.3+/-9.0% vs 41.3+/-7.0%; p=0.003). The extent of right ventricular end-systolic area enlargement and decrease in fractional area change did not correlate with the degree of pulmonary vascular obstruction. Patients who were restudied at 6 weeks showed minimal improvement in echocardiographic findings, despite almost complete resolution of perfusion defects on lung scan.

CONCLUSIONS

The extent of right ventricular dysfunction in hemodynamically stable, previously normal patients with acute pulmonary embolism does not reflect the extent of the perfusion abnormalities. Further, right ventricular enlargement and systolic dysfunction are present and persistent despite treatment with heparin and warfarin therapy or vena caval interruption.

Pulmonary embolectomy after single-lung transplantation

Single-lung transplantation for pulmonary hypertension results in a significant ventilation/perfusion mismatch with dramatic shift of blood flow, but not ventilation, to the replacement organ. This raises concern that the patient may be precariously dependent on the function of the transplanted lung. We report the successful management of a massive central pulmonary embolus to the transplanted lung in a 43-year-old woman 4 years after single-lung transplantation for primary pulmonary hypertension.

Management of massive pulmonary thromboembolism complicating diabetic ketoacidosis

Intravascular volume depletion secondary to diabetic ketoacidosis may result in thrombosis of major blood vessels. Without anticoagulation these thrombi can embolize to the lungs and compromise cardiopulmonary function. When this occurs early surgical pulmonary embolectomy is indicated to salvage a failing right heart.

Echocardiographic evaluation of pulmonary embolism and its response to therapeutic interventions

Imaging and Doppler echocardiography permits assessment of right ventricular size and systolic function and of pulmonary arterial pressures, and it may facilitate detection of thromboemboli within the heart or pulmonary artery. In patients with acute pulmonary embolism of sufficient severity to appreciably increase right ventricular afterload, the right ventricle becomes dilated and hypokinetic. Tricuspid regurgitation is generally apparent, but in the absence of preexisting pulmonary arterial or left heart pathology, the regurgitant flow velocity suggests only mild to mild-moderate elevation of pulmonary arterial systolic pressure. The absence of a greater degree of pulmonary hypertension reflects the inability of the previously normal, nonhypertrophied right ventricle to generate a mean pulmonary arterial pressure in excess of about 40 mm Hg. The echocardiographic abnormalities resolve during recovery from pulmonary embolism. Currently being investigated is the question of whether right heart abnormalities resolve more rapidly with thrombolytic therapy than with heparin therapy alone.

Pulmonary embolectomy: a 20-year experience at one center

Between 1968 and 1988, 96 consecutive patients with acute massive pulmonary embolism underwent pulmonary embolectomy under cardiopulmonary bypass. The operative mortality rate was 37.5%. We analyzed 12 clinical and hemodynamic variables by univariate and multivariate analyses to assess the predictive factors of postoperative outcome. Multivariate analysis disclosed that cardiac arrest and associated cardiopulmonary disease were independent predictors of operative death. Long-term follow-up (range, 2 to 144 months; mean, 56 months) information was available for 55 of the 60 discharged patients: 6 had died, and 5 complained of persistent mild or severe exertional dyspnea (New York Heart Association class II). These results help assess the preoperative risk in patients undergoing pulmonary embolectomy. They also show that, in the few patients who do not benefit from optimal medical therapy, pulmonary embolectomy remains an acceptable procedure in view of the long-term results.