Quantitative Assessment of RV Strain Using cMRI Following Catheter Intervention on PE (RVEF)

November 8, 2017 updated by: Charles Hennemeyer, University of Arizona

Quantitative Assessment of Right Ventricular Strain Utilizing Cardiac Magnetic Resonance Imaging: Development of an Optimal Measure of Treatment Response Following Catheter-directed Interventions on Sub-massive Pulmonary Embolism.

Acute pulmonary embolism (PE) is a condition in which the vessels carrying blood to the lungs become suddenly blocked, usually by a blood clot. There are a number of adverse consequences that result, with one of the most significant being strain on the right side of the heart (which must push blood through the blocked arteries to the lungs). Although this strain on the right heart is very important, current methods for measuring it are flawed. The standard practice is to obtain an echocardiogram (ultrasound of the heart), from which indirect measurements of the size of the heart are used to make inferences about right heart strain. This method can help guide management in some patients, but it in not a sensitive test and does not provide detailed information.

Patients with PE are treated with blood thinning medications. Some patients may be referred to the Interventional Radiology (IR) team for endovascular intervention, in which catheters are placed into the patient's vessels under radiologic guidance and advanced to the lungs to remove the clot entirely.

Cardiac magnetic resonance imaging (MRI) is a well-established imaging technique that produces highly detailed images of the heart's structure and function, with no risks to patients of ionizing radiation or intravenous contrast. Cardiac MRI is far superior to echocardiogram in evaluation of the right side of the heart, however it has not been widely used in the evaluation of patients with PE. We propose that by using a fast MRI protocol, we will be able to detect right heart strain with more accuracy than echocardiogram. Furthermore, we hypothesize that MRI images obtained before and after IR catheter-directed therapy will demonstrate the degree to which strain is relieved with this treatment. Finally, we believe that using MRI may help to guide management of patients with PE by detecting early or mild heart strain before it progresses.

In order to test these hypotheses, we plan to image PE patients who have been referred to the IR team with MRI. Patients recruited for this study will undergo two short MRI scans - one immediately before treatment, and one after completion of IR treatment (which lasts approximately 12-24 hours).

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Pulmonary embolism occurs when embolic material (usually clot in the venous system) travels to the heart and lodges in the pulmonary vasculature. This obstruction, if significant, can lead to pulmonary arterial hypertension, which places increased demand on the right ventricle (RV), which must pump against the blockage. This can manifest as right ventricular dysfunction (RVD), which is characterized by dilatation of the RV, wall motion abnormalities and other structural and functional changes. There is a significant body of data demonstrating that function of the RV is an important prognostic indicator in patients with acute PE. In these studies, RVD allowed identification of patients who, although clinically stable on presentation, were at risk for hemodynamic instability and high morbidity/mortality. As a result, many authors have suggested that RVD represents an important indication for more aggressive therapy in patients with submassive PE.

Currently, echocardiography is the most commonly used method for evaluating the RV in acute PE. However, obtaining quality imaging of the RV using echocardiography is technically difficult, and determining a reliable indicator of RV function has proved challenging. A number of markers of right ventricular function have been described, including size criteria, ejection fraction, wall motion, tricuspid regurgitation, paradoxical septal motion, and others. However, there is no general consensus on which methodology or measurements produce the most clinically meaningful data. The American Heart Association guidelines for submassive pulmonary embolism use the ratio of the right ventricle to left ventricle at end diastole (RV:LV ratio), which is defined as greater than 0.9 in patients with RVD. However, there is a large degree of heterogeneity in echocardiographic criteria for RVD used in the literature.

Additionally, the quantitative data provided by echocardiography is suspect, as they show only modest correlation with cardiac magnetic resonance imaging (cMRI) or computed tomography (CT) in evaluation of the RV. Even when specifically utilizing the American Society of Echocardiography guidelines, echocardiography proves to be significantly less accurate than cMRI for evaluation of the RV, especially in patients with a dilated ventricle.

Cardiac magnetic resonance imaging is considered the reference standard for accurate evaluation of ventricular structure and function. It has proven its accuracy, reliability, and prognostic value in the setting of other pathologies that result in RV dysfunction, such as pulmonary hypertension. However, to date, this modality has not been used to provide detailed information about the structure and function of the RV in patients with acute PE.

Recently, new therapies for acute PE have come into use that allow more precise treatment of the embolus itself through the use of endovascular catheters. These catheter-directed therapies (CDTs) deliver thrombolytic medication or other treatment strategies directly to the pulmonary circulation. There is a strong body of evidence supporting the use of these therapies, and some devices have been FDA-approved for this indication. Despite this, there is a lack of definitive markers for the patients who would benefit most from this therapy. Additionally, techniques currently used to attempt to quantify response to therapy (such as RV:LV ratio) are not ideal. There remains a need for a quantitative method for evaluating the structure and function of the RV in patients with acute PE in order to determine their risk for hemodynamic compromise, the need for CDT, and response after therapy is completed.

Study Type

Observational

Enrollment (Anticipated)

10

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Probability Sample

Study Population

Approximately 10 patients will be recruited for the study. Participants will be patients who present to the emergency department or are inpatients in the hospital, who are found to have a diagnosis of acute pulmonary embolism (confirmed by computed tomography pulmonary angiography), and who have been referred to Interventional Radiology for evaluation for CDT. Patients appropriate for recruitment into this study will have large PEs involving lobar branches or more central segments of the pulmonary arteries. However, patients with massive PE (resulting in hemodynamic instability) will not be appropriate participants for this study.

Description

Inclusion Criteria:

  • Participants will be patients who present to the emergency department or are inpatients in the hospital, who are found to have a diagnosis of acute pulmonary embolism (confirmed by computed tomography pulmonary angiography), and who have been referred to Interventional Radiology for evaluation for CDT. Patients appropriate for recruitment into this study will have large PEs involving lobar branches or more central segments of the pulmonary arteries.

Exclusion Criteria:

  • Exclusion criteria will be limited to prisoners, pregnant women, patients for whom English or Spanish is not a first language, severe claustrophobia, and other routine contraindications for MRI. Patients with massive PE (resulting in hemodynamic instability) will not be appropriate participants for this study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Only
  • Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Measure RVEF prior to and after catheter directed therapy to remove pulmonary thromboembolus
Time Frame: 2 years
Will predict severity of PE and identify patients that would most benefit from catheter therapy
2 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Arizona

Investigators

  • Principal Investigator: Charles Hennemeyer, MD, University of Arizona

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Anticipated)

December 1, 2017

Primary Completion (Anticipated)

December 1, 2019

Study Completion (Anticipated)

December 1, 2019

Study Registration Dates

First Submitted

November 7, 2017

First Submitted That Met QC Criteria

November 8, 2017

First Posted (Actual)

November 14, 2017

Study Record Updates

Last Update Posted (Actual)

November 14, 2017

Last Update Submitted That Met QC Criteria

November 8, 2017

Last Verified

November 1, 2017

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UArizonaIR

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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