Why hypertrophic cardiomyopathy may be widely underdiagnosed
While hypertrophic cardiomyopathy (HCM) has been considered a rare disease for decades, the recent focus on HCM with the introduction of the first drug therapy has made many experts realize the large lack of standardization on imaging reports may have led to a significant underdiagnosis of this patient population.
This concern was echoed by several experts who attended an HCM forum hosted by the American Society of Echocardiography (ASE) in June to hash out what is needed to advance HCM care. Information gathered at that forum is being used to determine where development is needed to improve care and to create an agenda for a larger HCM meeting in 2024.
One of these HCM experts was Srihari “Hari” Naidu, MD, director of the cardiac catheterization laboratories and Hypertrophic Cardiomyopathy Center of Excellence at Westchester Medical Center in New York, who took time out at the forum to speak with Cardiovascular Business. He said the lack of standardization for how diagnostic imaging in conducted and what is reported has been a big headache for proper diagnosis. This often requires rescanning patients if they are referred to HCM Centers of Excellence, because measurements and other key HCM observations are sometimes missing. He said the original imaging can be used to find this information, but often it is not included with the imaging reports. This missing information and a lack of knowing what to look for may have led to many patients with cardiac issues being misdiagnosed and underdiagnosed for HCM.
"I think there has been huge underdiagnosis of HCM," Naidu explained. "It is hard to imagine why, because a year or two later when they come to see me, the HCM is very obvious on echo, but for some reason, it was missed. And it can be missed by cardiologists or internists who really should know what they are doing. Part of it could be that the referring physician gets the report and it does not really capture how thick the heart is or where it is thick. The picture is worth a thousand words, but most reports do not have a picture on it, so it can be missed."
He said it is also important to report where in the heart the thickening of the myocardium is occurring. Historically imagers usually use the anterior wall and may not report the focal basal hypertrophy.
"For this reason, the reports may say 1.3 cm, but they missed a 1.8 cm because the imager was told not to report that. So the reports over the years will show normal thickness, normal thickness, normal thickness, but if you had the echos you would see the massive hypertrophy. This is a fundamental problem and why patients are upset. They don't understand how they have been seeing a doctor for five years and all of a sudden, their thickness goes to 2.8 cm. We know that there is no way that it was not somewhat thick on earlier exams and we need to do a better of assessment," Naidu explained.
When there is suspected HCM in a patient and they get sent to an HCM Center of Excellence, the imaging often needs to be performed again. Naidu said getting insurance to cover a redo echo is usually not a big problem, but that is not the case with cardiac MRI, which are more expensive. He said this is not fair to the patient because it is not their fault that the HCM was missed or just not reported in earlier exams.
"I think that is a huge problem. While HCM has been a small pond of patients, we have been able to just say do a preliminary echo or ECG and if it looks suspicious, send the patient our way and we will do a more in-depth evaluation, analysis and MRI. But now, those days are gone, because there is so much more awareness and patients want things to be done right the first time. It's not fair to say find this and send them to me, we need to make people experts where the patients are. We need to move past that and understand that that first echo needs to be better. We need to be able to evaluate echos between institutions and say that was a good enough echo and now we can move on to an MRI and we will have all the elements we need."
The need to standardize what should be reported and how to better perform measurements were key discussions by experts who met at the HCM forum. They also discussed if sonographers or technologists should be trained to better image or recognize HCM, and if they should be certified.
Once standardized imaging and reporting protocols are set, then the next step is to better identify the phenotypes of HCM, which determines the course of treatment. This also will help better facilitate registry data so therapies and drugs used to treat different types of HCM patients can be better evaluated and evidence-based guidelines can be written.
Naidu said the type of HCM will indicate the problems to watch for in patients. Apical HCM often means the patient has a high likelihood of developing atrial fibrillation and diastolic disfunction. In obstructive HCM, he said the concern is more about long-term systolic disfunction, heart failure symptoms, syncope and how to best alleviate the left ventricular outflow tract (LVOT) obstruction.
"We need to recognize that all these things have different paths, and it all starts with diagnosis, so the diagnosis needs to be accurate and very consistent across different centers," Naidu said.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: dfornell@innovatehealthcare.com