Should systemic thrombolytic therapy be considered a first-line treatment in acute pulmonary embolism?

We read the article, entitled “Successful treatment of a pulmonary embolism with low-dose prolonged infusion of tissue-type plasminogen activator in a 37-year-old female in the early postoperative period,” by Aykan et al. (1) in Anatolian J Cardiol 2014; 14: 400-2. We believe that it can be a really good idea to administer low-dose thrombolytic agents in pulmonary embolism to minimize possible complications. Of course, randomized controlled trials should be performed to test the reliability of this low-dose regimen. We are curious as to why the authors did not consider using well-proven modalities, like percutaneous ultrasoundaccelerated thrombolysis (PUAT) and directed thrombolysis (CDT) (2-4). There is no clinical study available so far comparing systemic thrombolytic therapy and endovascular thrombolytic therapy, but this kind of study can take considerable time and can also yield major hemorrhagic complications up to 20%; so, it is preferable to go for an endovascular approach, where direct administration of a thrombolytic agent into the thrombus is possible (4, 5). In PUAT therapy, the dose of tissue plasminogen activator (tPA) is 0.5 mg/kg. Engelhardt et al. (4) even showed the efficacy of doses as low as 20 mg tPA for treatment of pulmonary embolism. In our institution, 4 patients with massive/sub-massive pulmonary embolism received PUAT with 0.5 mg/kg tPA infusion for 6 hours. We did not experience any complications or mortality. Remarkable improvement in right ventricular functions was shown in all patients with echocardiography and computed tomography. Measurements of right ventricle and left ventricle diameters could also be a very useful tool in assessing the efficacy of treatment in massive pulmonary embolism. We would like to hear the authors’ opinions regarding the concerns mentioned above.