Council News | Wissam A. Jaber Michael McDaniel, Henry A. Liberman, Tanveer Rab

The cardiovascular community, in general, and the interventional cardiologists in particular, have seen a recent rise in the interest to manage and invasively treat patients with acute pulmonary embolism (PE). This was echoed by a trend in multiple academic centers to form a pulmonary embolism response team (PERT¹), and recent publications examining the effectiveness of catheter directed therapy (CDT) in PE². This interest is not without its own merit. PE is a common disease, with significant morbidity and mortality, accounting for over 200,000 annual deaths in the United States^3,4 and, in some cases, leading to chronic pulmonary hypertension5.

While more than half of acute PE patients present with low-risk features, about 5 percent present with massive PE (defined as sustained hypotension, or requiring pressors) with a mortality rate of over 50 percent. Submassive PE occurs in 40 percent of all PE population and is defined as normotensive patients with signs of right ventricular (RV) strain (RV enlargement, elevated cardiac biomarkers, significant electrocardiographic abnormalities) ⁴. This latter group has a mortality rate of over 13 percent⁴, representing a therapeutic challenge. These patients can suddenly deteriorate, have recurrent PE, or progress to chronic RV dysfunction or pulmonary hypertension. Although systemic thrombolytic therapy can be helpful in reducing the risk of acute recurrence and escalation of treatment⁶, it carries an increased and sometimes unacceptable risk of serious bleeding⁷. An attractive alternative is a percutaneous approach where much lower doses of thrombolytics are locally delivered through catheters embedded in the pulmonary thrombi2, thus deriving benefit while minimizing systemic side effects. Surgical embolectomy is another possible option with potentially good outcomes in selected cases.

Because therapeutic options offered to PE patients varied widely depending on the treating or consulting service, we, at Emory University, formed a multispecialty PERT consisting of a small number of cardiologists, pulmonologists, interventional radiologists, and cardiothoracic surgeons with an interest in PE. A treatment algorithm (Figure 1) and general guidelines were agreed on. A 24-hour consulting service was created, and, since its inception in 2012, over 300 patients were evaluated—a proportion of whom were treated with CDT, systemic thrombolytics and surgical embolectomy. A prospective registry was created to capture all involved patients, mostly for quality control. Figures 2-4 show examples of these patients.

The following factors are important for the success of an interventional PE program:

• Buy-in from multiple specialties: Traditionally PE patients are not admitted to the cardiology service and both the treating physicians and those traditionally asked to consult on patients with PE (pulmonologisst, vascular surgeons, interventional radiologists, etc… depending on the prevailing culture at the specific institution) need to be in agreement with the implemented protocols and treatment algorithms. Pulmonologists generally are not in agreement with catheter based treatment for submassive PE, consistent with the CHEST guidelines⁸. This factor, being the most important initial hurdle to bypass, is best addressed through the identification of a PERT champion and enthusiast in each involved specialty and the conduction of multiple preparatory meetings and discussions with these individuals. In our example, preparatory meetings took several months, and involved cardiology, pulmonary, cardiothoracic surgery, interventional radiology, and emergency medicine specialists. 
• Marketing and education: The next step is to educate physicians and nurses about the PERT and its importance, through special meetings and grand rounds. We found that the most helpful strategy to capture the PE cases was to implement a protocol for the emergency physicians to call us on every patient diagnosed with PE. The protocol involved routinely checking cardiac biomarkers and echocardiograms on presentation. This protocol was met with enthusiasm by the emergency staff, as it helped them obtain a quick consultation and advice on disposition and treatment in a traditionally challenging patient population. Hospitalists and intensivists are the other groups whose endorsement is crucial.
• Ongoing meetings and reevaluations by all team members: It is important both to keep the momentum, and to refine treatment algorithms. Enthusiasm by the team members is important since they will be involved in a 24-7 call, and be frequently available for immediate multidisciplinary consultation by the team member who is on call.
• Familiarity with all aspects of PE treatment: For the same reasons an interventional cardiologist cannot treat coronary disease percutaneously without being familiar with medical management of stable coronary disease and myocardial infarction, an interventionalist cannot expect to treat PE with catheter therapy without being comfortable with treating all aspects of PE. This includes familiarity with systemic lytic use, anticoagulants, interpretation of diagnostic images and outpatient management. Moreover, a creation of an outpatient PE clinic is a very helpful step in the creation of a comprehensive, successful program.
• Quality checks: A registry was created to review effects and complication of percutaneous treatment for acute PE, similar to what has been done in percutaneous coronary intervention.

PE treatment will continue to evolve as more interest is being raised in the medical community. Multicenter cooperation and registries are necessary both to evaluate the impact of PERT implementation on patient care and to lay the ground work for much needed large randomized trials investigating the best treatment strategy for patients with submassive PE.

References

1. Kabrhel C, Jaff MR, Channick RN, Baker JN, Rosenfield K. Chest. 2013;144:1738-1739.
2. Kucher N, Boekstegers P, Müller OJ, et al. Circulation. 2014;129:479-486.
3. Goldhaber SZ, Visani L, De Rosa M. The Lancet. 1999;353:1386-1389.
4. Jaff MR, McMurtry MS, Archer SL, et al. Circulation. 2011;123:1788-1830.
5. Kline JA, Steuerwald MT, Marchick MR, et al. Chest. 2009;136:1202-1210.
6. Meyer G, Vicaut E, Danays T, et al. N Engl J Med. 2014;370:1402-141.
7. Chatterjee S, Chakraborty A, Weinberg I, et al. JAMA. 2014;311:2414-2421.
8. Guyatt GH, Akl EA, Crowther M, et al. Chest. 2012;141(2_suppl):7S-47S.

Keywords: ACC Publications, CardioSource WorldNews Interventions

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