While echo is the front-line imaging modality to identify heart failure in a patient, advanced imaging such as cardiac MRI or CT is increasingly being used to identify the specific etiology of the heart failure. Parwani said this allows targeted, personalized treatments for each patient.
"Echo is the first diagnostic test because it is the easiest. We can take this machine anywhere in the hospital. As a physician, I can scan my patients and make a diagnosis very quickly in the emergency room," Parwani said.
MRI, CT and nuclear imaging can be ordered if needed, but they involve more infrastructure that may limit their immediate use or access.
"At the same time, I think we need to realize there are inherent limitations with every modality. I think in the future we are going to learn how to incorporate multimodality imaging much more effectively in cardiology. And every hospital administration has to learn how to make that process efficient," she said.
She said this process usually will maintain an echo-first approach, but if questions remain unanswered, there needs to be a process to get the patients the right advanced imaging exams.
With advanced noninvasive imaging, why do we still need angiography?
Parwani said many hospitals and doctors still have invasive angiography ingrained in their minds as the next logical test after an inconclusive echo, especially to assess if there is coronary ischemia. MRI and CT can show the anatomy of the coronaries very clearly to quickly rule-in or rule-out the role of plaque and ischemia. However, CT is used in less than 2% of cardiac imaging, even though it is readily available and can help avoid, or nearly eliminate, the need for diagnostic angiograms. Parwani said this also helps avoid exposing the patients to additional risks of an invasive procedure.
Cardiac MRI usage is also very low, she added. This is despite the fact that it offers both excellent anatomical and physiological imaging in addition to helping identify if there is a rare or mixed cardiomyopathy playing a role.
Phenotyping with advanced imaging can reduce transplant rejections
For heart failure patients that go on to heart transplants, Parwani said there is somewhat large margin of error, up to 20%, where there are mismatches in pathology between the donor hearts and the patients.
"The patient goes in for a heart transplant and the explanted heart gets a biopsy and then they realize the pathology they thought the patient had, they did not have. And this can really be reduced if we use the imaging to phenotype the patients using advanced imaging," Parwani explained.
New roles for echo in HCM and amyloid
In the past couple years, new drugs have been introduced to treat hypertrophic cardiomyopathy (HCM) using mavacamten and cardiac amyloidosis using tafamidis. This has caused an explosion of interest in diagnosing these patients for diseases that were previously difficult to treat or untreatable. However, while echo can identify these diseases, phenotyping them with echo alone can sometimes be difficult. Echo also may not be able to show small improvements in serial exams. This has given rise to artificial intelligence (AI) research to help make more confident diagnoses without the need for more expensive advanced imaging tests.
"I think in the next few years, with all the technology advances in echocardiography, in particular AI, we will be able to use echo for monitoring these patients to see how they are doing," she said.
Parwani said AI will be increasingly used to automatically assess left and right ventricular strain more accurately than it can be done manually. The AI will also correlate the measurements with prognosis. Overall, she said AI in the near future will make echo measurements much more reproducible and help alleviate workflow issues for sonographers.