Hypertrophic Cardiomyopathy: 3 New Articles of Interest

Podcast Transcript

Announcer:
Welcome to Cleveland Clinic Cardiac Consult, brought to you by the Sydell and Arnold Miller Family Heart, Vascular and Thoracic Institute at Cleveland Clinic.

Milind Desai, MD:
My name is Dr. Milind Desai. I'm a cardiologist at the Cleveland Clinic in Cleveland, Ohio. And, I am also the director of Hypertrophic Cardiomyopathy Center at the Cleveland Clinic. On behalf of my colleagues in the HCM Center, I would like to discuss three recent papers that we have published as part of the HCM Center. We are very excited about the results, as they cover a broad spectrum of HCM patients and have important implications in terms of diagnosis management, and risk stratification of these patients. So, let us start one at a time. A paper that we are very excited about and that was published a few months ago, it looks at patients who had obstructive hypertrophic cardiomyopathy needing cardiac surgery, surgical myectomy, plus or minus additional procedures. This paper studied about 2,268 patients that were evaluated at the Cleveland Clinic between 2002 and 2018.

Milind Desai, MD:
All patients had, as would be expected, obstructive cardiomyopathy. They presented to our tertiary care center for consideration of septal reduction therapy, surgical myectomy, mostly. This was a good representation of a standard HCM population. About a mean age was 54 years, and 55% were men. At the Cleveland clinic, we have always incorporated stress testing as part of our symptom evaluation. And, we divided this group of more than 2000 patients into folks that met class 1 indication for surgical myectomy. So, that included 1,318 patients while the remainder, we sent them for surgery at an earlier stage. Earlier, before they reach class one indication. The reason for sending them an earlier surgery was, they were intolerant to their medications, or we put them on a treadmill and they did poorly on stress testing in the setting of severe LVOT obstruction. So, those were the two groups. All of these patients underwent cardiac surgery.

Milind Desai, MD:
What we found was that more than six years of follow-up, after surgical myectomy, 11% patients met a composite endpoint of death or appropriate ICD discharge. There was... The mortality in hospital, mortality was extremely low at 0.6%. And, what we also found that the factors that were associated with long-term survival or outcomes were at increasing age, presence of concomitant coronary artery disease. But an interesting thing we found was, patients who we waited till they reached class 1 indication for surgery, they did much worse in the longer-term compared to the patients that were sent earlier for cardiac surgery, based on the decision-making that we discussed before. So, another important thing we found was, about 20% of our patients also underwent concomitant mitral valve or papillary muscle operation, and we did not pay an outcomes penalty as it relates to doing these combined procedures.

Milind Desai, MD:
Another important thing, the crucial point we found that patients who underwent earlier surgery, their long-term survival was very similar to age and gender matched, normal United States population. As compared to the patients who we waited to reach class one indication, they did significantly worse in the longer-term. So, to summarize the findings of this paper, at an experience center like the Cleveland Clinic, were we do a high volume of cardiac surgery for hypertrophic obstructive cardiomyopathy, our short and long-term outcomes are excellent. When evaluated by experienced provider and appropriately sent for an earlier operation, our outcomes are much better compared to waiting for an operation. So, this might be a potential paradigm shift in how we approach these patients. In fact, in the most recent HCM guidelines, there is now consideration for an earlier operation, especially at an experienced center after shared decision-making incorporating various factors, including patient preference, drug intolerance, as well as exercise incapacity. Also, discuss a recent paper that we have published in the field of hypertrophic cardiomyopathy.

Milind Desai, MD:
Essentially for a long time, we have recognized that there is a group of very elderly patients with longstanding hypertension, etc., who's heart have changed shape over the years as they have aged. And, a lot of these patients present with features that mimic and look very much like the standard hypertrophic cardiomyopathy patients. So, we have been interested in this population, we wanted to study their outcomes. This study is the largest, looking at such a population. So, we studied about 1,110 patients that were evaluated at the Cleveland Clinic, between 2002 and 2018. The mean age of this population was 80 years, so very elderly patients. The youngest person in this population was 75 years of age. And, 66% in this population were women. 72% of these patients had long-standing history of hypertension. And, because this is the elderly population, we also calculated an STS score, Society of Thoracic Surgeons score, which was a very high, as would be expected at 8.6.

Milind Desai, MD:
Interestingly, about 80% of these patients in this population had no HCM related risk factors. The standard risk factors that we have come to associated with hypertrophic cardiomyopathy. What we also found, interestingly, that 54% of these patients had severe outflow tract obstruction, with a gradient greater than 30 millimeters of mercury. In this population of obstructed elderly patients, 195 patients were also offered septal reduction therapy, 79% of them underwent surgical myectomy, while the remainder underwent alcohol septal ablation. We followed them up for little over five years at a median. And what we found was, as would be expected, the primary event rate, which was death or appropriate ICD discharge, but mostly death, was observed in about 50% of the patients. When we broke it down, 53% event rate in the non-obstructive population, 55% in patients with obstructive cardiomyopathy without a septal reduction therapy. But also, we found that long-term survival, long-term outcome event rate was 32% in obstructive patients who underwent septal reduction therapy.

Milind Desai, MD:
So in short, survival was improved in obstructive cardiomyopathy patients, if they underwent appropriately septal reduction therapy, especially at an experience center like the Cleveland Clinic. Again, because this was an elderly higher than usual risk population. The expected mortality based on the STS score was 9.2%, the expected mortality, but the observed mortality at the Cleveland Clinic was only 2.5%. So to summarize, the elderly population, there is a subgroup of elderly patients who present with a clinical picture that looks very similar to the garden-variety hypertrophic cardiomyopathy, with or without LVOT obstruction. These patients, if diagnosed appropriately and managed well at an experienced center like the Cleveland Clinic, their outcomes are very good. In fact, the outcomes of the obstructive cardiomyopathy group who underwent septal reduction therapy was very similar to age and gender matched population, as opposed to the other two subgroups.

Milind Desai, MD:
If you do not have surgery with obstruction, or if you have non-obstructive cardiomyopathy, your outcomes were far worse compared to age and gender matched population. So, this is something important that needs is to be taken into consideration, and potentially offered to our patients, especially at an experienced center with experienced providers. The third paper I would like to discuss is on the completely opposite spectrum, that is pediatric patients with hypertrophic cardiomyopathy. That is patients who were less than 18 years. And in addition, to my colleagues in the adult realm of hypertrophic cardiomyopathy, including cardiac surgeons, I would also sincerely like to thank our pediatric cardiology colleagues, whom we collaborated with very closely to get this paper to fruition. So, this paper involve 398 pediatric patients all under the age of 18 years, with a median age of around 14 years. These were evaluated at our center between 2002 and 2018.

Milind Desai, MD:
And, all patients underwent extensive evaluation, including clinical visits, as well as echocardiography. A small subgroup also underwent cardiac MRI in the later part of this study. What we wanted to look at was their endpoints, and we looked at the composite endpoint of death, need for ICD, appropriate ICD, need for heart transplant, as well as need for surgical myectomy. Interestingly, what we found in this nearly 400 patients is that, only about 33% of patients were symptomatic. 33% had symptoms, and these included dyspnea, shortness of breath, chest pain, or syncope, passing out. Only 45% had a family history of hypertrophic cardiomyopathy, and about 27% were on a beta-blocker therapy. Essentially, this is a pediatric population and about 146 patients underwent genetic testing, of which only 91 were gene positive for HCM therapy. So, even though this data was obtaining pediatric population, the genetic positivity rate was not that high.

Milind Desai, MD:
And as I mentioned, we did a detailed echocardiography analysis, including measurement of Z-score of the maximum left ventricular wall thickness. what we found was that, 23% had extreme left ventricular hypertrophy with a Z-score of more than six. That would roughly correlate to an adult maximum septal thickness of greater than three centimeters. 8% of these patients had a significant outflow tract gradient, more than 30 millimeters of mercury. What we also found when we followed these folks up to a median of 5.9 years, or close to six years, what we found was the composite event rate was observed in 42 patients or 12% of the population, of which 29 of them under went myectomy. The factors that were associated with adverse outcomes included presence of VT, ventricular tachycardia, a Z-score of greater than four.

Milind Desai, MD:
So important to know, a Z-score of greater than six would roughly correlate with an adult septal wall thickness of more than three centimeters, which is considered an independent risk factor. So, perhaps in pediatric population, the threshold needs to be lower. That is one of the key findings in this paper. And of course, presence of symptoms would be expectedly associated with need for surgical myectomy. Another crucial finding is in a well-managed patient population at an experience center with comprehensive availability of pediatric adult genetic, as well as cardiac surgical services, the outcomes, the adverse event rate of this population was 0.5% per year for sudden cardiac death or appropriate ICD discharge. Which is excellent in terms and reaching towards adult HCM management like numbers.

Milind Desai, MD:
But I'm going to reiterate, the pediatric population is not just younger HCM patients. We have to look at them in a different way, work them up differently. We have to take into consideration their emotional psychosocial toll, as well as importantly, absolute number-wise, the thresholds in terms of risk stratification, we have to recognize maybe potentially lower, as compared to the adults. Especially, the wall thickness or in terms of the Z-score. So, thank you for paying attention to these great research. Thank you for paying attention to this, what I believe is practice changing research. In summary, we have demonstrated that in an experience center, like the Cleveland Clinic, we take care of the full spectrum. We are very capable of taking care of the full spectrum, right from little babies to extremely elderly individuals with excellent, excellent outcomes. Thank you.

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