Cath Lab Digest

There are three categories of pulmonary embolism (PE) patients:

1. Massive PE patients account for 5%. These patients present in cardiogenic shock, so they are the most serious group, and they have a high mortality rate.
2. The submassive group accounts for 40%. Submassive patients are hemodynamically stable, with normal blood pressure, but present with evidence of right ventricular dysfunction or right heart enlargement, so with imminent right heart failure. 
3. The remaining patients, about 55%, will present as minor PE patients, and we normally don’t treat them with anything other than the traditional anticoagulation. 

How far out are you following patients in the SEATTLE II trial?

We see patients 30 days after discharge to make sure there have been no readmissions or any other complications that develop. I continue to follow these patients out to a year. When I was at the Veith meeting last year, we presented the results of 24 patients. My single-center experience is currently at 55 patients. We are still seeing the same degree of regression in the right ventricular/left ventricular ratio. 

Current accepted standard of care in the treatment of patients with PE is anticoagulation for all three categories: massive, submassive and minor PE. When patients get to the point where they are obviously dying, the physician will usually get more aggressive and give tPA systemically, and this has saved lives. If the patients are easily resuscitated and they become more stable, the general trend is to just anticoagulate. Forty percent of all PE patients are submassive patients, which means they are hemodynamically stable. They have a normal blood pressure, normal pulse rate, and normal oxygen saturation, but their right heart is enlarged. Right heart enlargement puts patients at risk of developing sudden death, because they can easily slide into the massive PE category if they re-embolize or deteriorate. All three categories of PE patients should not be treated the same. It is evident we should be treating these patients differently and we should be more aggressive with the massive and submassive patients. 

The Ekos catheter takes 20-25 minutes to put into place. It is very well tolerated. Within 12 hours for a bilateral PE and 24 hours for a unilateral PE, the treatment is over and the patient can leave the ICU. They are anticoagulated, of course, but the risk of sudden death is diminished, because that obstruction has been immediately improved. The right heart normalizes, an immediate benefit. The long-term benefit is in preventing primary pulmonary hypertension that can develop as many as ten years later, potentially turning the patient into a cardiac cripple. 

We also measure pulmonary artery pressures pre and post treatment. After we treat the patient, the PA pressure can be measured through the existing Ekos catheter with the patient in the ICU. We have seen a nice reduction in pulmonary hypertension. We are looking for a decrease in the right ventricular/left ventricular ratio within 48 hours ± 6 hours, along with a safety profile.

With traditional therapy, a post treatment CTA is rarely performed. We have shown that ultrasound-assisted thrombolysis allows for a significant decrease in right ventricular/left ventricular ratio, and with that reduction, the patient benefits greatly in the both the short term and long term. I believe ultrasound-assisted thrombolysis is going to be a game-changer. Quite possibly, we are going to redefine standard of care for as many as 50% of PE patients.

Dr. Tod Engelhardt can be contacted at tengelha@ejgh.org.

Recommended reading

1. Engelhardt TC. Catheter-directed ultrasound thrombolysis and the reduction of right ventricular dysfunction in acute pulmonary embolism. Cath Lab Digest 2012 Jan; 20(1). Available online at http://www.cathlabdigest.com/articles/VeithSymposium-Hot-Topics-Peripher.... Accessed December 12, 2012.