I work at cincinnati, children’s hospital in the exercise lab um for the next 20 minutes or so i’m going to go over a talk that i gave at the american college of sports medicine. It is an overview of cardiopulmonary exercise, testing indications, safety and prognostic significance. I have no disclosures other than the fact that cincinnati is a beautiful city, so in the next 20 minutes or so i’m going to hit on a variety of topics. First i’m, going to discuss. Why exercise testing is important in the congenital heart disease population then i’m, going to give a very brief overview on what cardiopulmonary exercise testing is followed by an overview of the indications for exercise testing in the congenital heart disease population. Lastly, i’m, going to go a little more in depth into notable papers, evaluating markers of potential prognostic significance for specific heart disease lesions. So, first off patients with complex congenital heart disease are now surviving longer and into adulthood. Here you can see that in the old days, complex congenital heart disease was a very difficult diagnosis to survive even the first year, but as surgery and cardiology care is improved. The survivors of these lesions are now living longer lives, and this is old data. Our survival curves have continued to improve, so we now have chd patients that make it to adulthood and can tell us both subjectively how they feel, and we can measure objectively how they perform. This study of the royal brompton hospital in london involved over two thousand patients tested.
This is an interesting study for a couple of reasons. For one, the vast majority of prepared, chd patients say they feel good, as evidenced by the large percentage of nyha1 classification. On the other hand, the majority of these nyha1 patients performed abnormally on formal exercise testing, with an average percent predicted vo2 of 78 percent. I think we can look at this two ways. One is that quote: unquote healthy and fit chd patients have a poor understanding of what normal functional capacity should actually be. On the other hand, when these patients report that they’re fatigued such as the nya ha class 2 and 3 patients they’re often quite accurate and are significantly depressed by the time they report symptoms. So if we can’t trust patients perception of their health, at least we can trust the science except the science is lacking an exercise of chd patients, not focusing on the results of the study. This slide mostly just shows the lack of studies that were able to be included in this meta analysis. The only inclusion criteria, english speaking comparison, healthy controls, complete data, not a very high bar, so some brief background into what exactly an exercise test is. It is a very useful tool to gather insight on both the cardiac and pulmonary function, as well as aerobic fitness for our patients it’s. The only widely used test that assesses the dynamic function of the heart, with all other studies, such as echo, cardiac, mri and calf.
All being performed during a resting state here is a picture of one of our three testing bays in our exercise laboratory. This space was recently renovated in 2017. Each bay has a treadmill and a cycle ergometer. We have the ability, with a ge machine here, to assess ekgs continuously during testing. We have two different metabolic carts, the med graphics and the parvo medics. We also have the ability to non invasively, assess cardiac output using using the iron core and then not picture behind us as a crash cart, which is which is available for every test on the right is just a sample of some of the common variables we measure In our lab, as a quick aside, is it safe to put these complex patients through a maximal exercise test? Maybe the best study evaluating the safety of formal cardiopulmonary exercise testing came from the boston group. Over a three year period, over 2500 patients were tested with many of them having complex, cardiac anatomy and repairs in this whole cohort, only three patients required cardioversion and all three of them had an existing icd in place. That gave an appropriate shock. I think this study helps to demonstrate if you’re well prepared, well trained and smart about who you’re testing that formal exercise testing should be safe in this population. So now i’m, going to briefly go over the indications for cardiopulmonary exercise testing in healthy children. We mostly test to determine if the symptoms they are having are tied to any pathology.
More often, it is not but it’s kind of like finding a needle in a haystack, but sometimes they are abnormal, like this teenager with palpitations, who turned out to have catecholaminergic polymorphic ventricular tachycardia i’m not going to go over every one of these. But we are getting better at looking for exercise abnormalities in other patients more often than not. When we look, we find interesting findings and frank abnormalities. So basically, this slide is just a plug to remind everyone that cardiopulmonary exercise testing isn’t just for patients with heart or lung disease. Now to the meat of the talk, cped and chd patients, there is a wide spectrum of disease, and thus the uses of cardiopulmonary exercise testing depends greatly on the individual, patient and lesion being studied. For instance, this patient on the left, who is cachectic with multiple sternotomies, is going to have a much different indication and results of a c pet than arnold or sean white or teddy boosky. As a bonus for the future trivia. Arnold had a bicuspid aortic valve sean white had tetrology of fellow and teddy boosky had a repaired, atrial septal defect, one indication for c pet and chd patients is to identify abnormal responses to exercise, for example, to evaluate the systolic blood pressure responses to exercise in hcm Patients or to evaluate for sinus no dysfunction in atrial switch patients to trend vo2 in repaired, complex chd patients or to evaluate for perfusion deficits in patients with coronary artery abnormalities.
Cpec can also identify chd patients who might benefit from therapy. For example, a tetralogy of fellow patient with severe pulmonary insufficiency, progressive right, sided chamber, dilation and worsening vo2 are often sent for pulmonary valve replacement. Fontan patients who desaturate during exercise and have a depressed vo2 might be referred for. Fenestration closure heart failure. Patients can be sent for afterload reducers cpeg can also be used to assess for the efficacy of specific treatments, for example, is a long qt patient being adequately beta blocked? Is a chd patient who’s currently undergoing cardiopulmonary rehabilitation? Improving? Is the patient with pulmonary hypertension improving on their pulmonary vasodilators? Lastly, we’re going to talk about markers of prognostic significance, despite lack of great research, there’s been a few notable studies, evaluating prognostic significance of cped for specific chd populations, and these studies are all going to be better tools to predict the future than google or the magic 8 ball and when i did this google search it was during the heart of soccer season, but i loved that number. The number two hit on google was still how to grow up and be a unicorn in general. In chd all comers lower vo2 is seen as a poor prognostic indicator. In this study from the royal brompton involving 335 total patients across a wide range of diagnoses, peak vo2 was found to be a predictor of hospitalization or death in this graph. Here you can see that the two year survival for patients with a vo2 of less than 15.
5 milliliters per kg per minute was an abysmal 50. The reverse was also true in that patients with more normal indexed vo2 values had a much more favorable morbidity and mortality curve. This other study, also from the royal brompton, looked at heart rate reserve defined here, which is something we don’t typically consider during cpet. In this study, involving 727 patients, heart rate reserve is abnormal and non survivors compared to survivors. This figure here demonstrates that patients with a lower heart rate reserve are shown to have a higher probability of death compared to patients with a larger and more normal heart rate reserves now i’m, going to transition to studies evaluating specific lesions since i’m. Assuming everyone listening to this talk is not a pediatric cardiologist when we discuss the individual lesion i’m going to have a diagram of the normal heart, followed by an unrepaired heart and then the heart after surgery. Here we have an unrepaired single ventricle patient hypoplastic left heart syndrome, with the next picture, demonstrating how the anatomy looks following the three stage: single ventricle palliation notable to the physiology is a lack of a subpulmonary ventricle, meaning that all the pulmonary blood flow arrives to the Lungs passively, through the rerouted systemic veins. This difference in physiology results in profound changes in their exercise function with the majority of these patients having rather markedly abnormal vo2. This study out of boston involved 148 fontan patients with an average age of 21 plus or minus six years old.
The average index for body rate vo2 for survivors was 21.8 milliliters per gauge per minute compared to 16.3 milliliters per kg per minute in the 16 patients that died when breaking this down further, they showed that having an indexed vo2 of greater than 16.6 milliliters per kg Per minute and a peak heart rate, greater than 122 beats per minute was protective in preventing death in fontana patients. The boston group then decided to see how the vo2 trend over time predicted death. In this study, they evaluated 130 patients, who had at least two exercise tests six to 30 months. Apart and 81 of these patients were nyha class 1., the average baseline vo2 was 22 plus or minus 6. Milliliters per kg per minute was about 61 predicted and there was a 10 incidence of death or transplant on average peak vo2 declined for patients who died or underwent transplant, but remain stable, and those who did not. This provides somewhat compelling justification for trending the vo2 over time in these patients, which is why the 2018 aha acc guidelines for the management of adult congenital heart disease recommends periodic exercise tests in asymptomatic, fontan patients. This study out of mayo mimics the results from the previous study we looked at, which is nice to add additional reproducibility to these findings. The study included 145 patients with 79 percent being nyah class 1.. The overall baseline peak vo2 was 23 plus or minus 5 milliliters per kg per minute or 63 percent of predicted, and there was a percent predicted peak vo2 decline by mean of 1.
7 plus or minus 0.9 percent per year. This graph shows that a peak vo2 decline of greater than 3 percent a year is tied to increased cardiovascular events and we’ve added this to our local fontan management guidelines, for when we interpret serial tests in these patients. So, in summary, for the boston data for every 10 decline in peak vo2, there is a doubling of the hazard for death or transplant for the mayo data, a decline in the percent predicted vo2 by greater or equal to 3 per year or 2 standard deviations from The mean was the only predictor of five year risk of cardiac event. Both of these studies add justification to the importance of serial sea pets and fontan patients. Our next lesion is ebstine’s anomaly, which seen here is downward displacement of the tricuspid valve, resulting in a smaller right ventricular cavity, an atrialized portion of the right, ventricle and often poorly functioning valve. This study, out of the royal brompton, looked at 51 patients with ebstein’s anomaly. Overall 22 patients had an unplanned event defined as tricuspid valve intervention, unplanned hospitalization or death. In this cohort, a percent predicted vo2 of less than 60 percent resulted in a rather markedly worse event rate with a 90 percent risk of event after six years, as opposed to a 30 risk and those who had a higher vo2 now to change over the transposition Of the great vessels seen here in the aorta and pulmonary arteries arise from disconcorded ventricles, the older method for palliating.
This was the atrial switch, which is seen here when the systemic venous return is rerouted to the left, ventricle and the pulmonary venous drainage. As we routed to the right ventricle as these patients age, they often have baffle leaks and stenosis ventricular dysfunction, arrhythmias and worsening exercise tolerance. In this interesting study, looking at 274 patients repaired via the atrial switch, they looked at not just the vo2, but also the ve vco2 slope. The authors are able to show that both an elevated, ve, vco2 slope of greater than 35 and a percent predicted vo2 of less than 52 percent were more powerful prognostically when paired, together than they are individually, as seen in figure 3.. The other figure provides further details and that the patients repaired via an atrial switch with markedly abnormal functional capacity and ventilatory efficiency. Don’T tend to do well with only about 20 percent of the most affected patients being free from death or cardiac events at five years. Our last lesion is tetralogy of fellow shown here. These patients have a large ventricular, septal defect, pulmonary stenosis, overriding aorta and right ventricular hypertrophy. The repair includes placing a patch across the vsd and often pulmonary valve excision, which results in severe pulmonary insufficiency and often progressive right. Ventricular dilation and exercise intolerance. This study in 221 patients evaluated risk factors for a death within 30 days of pulmonary valve replacement. There were a total of five deaths and they found that patients with a peak vo2 of less than 17 milliliters per kg per minute had a higher risk of death shortly after pulmonary valve replacement, as opposed to higher values shown here.
The last study we were going to look at is probably one of the best. This multi center study out of europe sought to determine the most useful prognostic markers for tetralogy of fellow patients long after their primary repair. They didn’t limit it to just exercise testing. Their cohort was 875 patients with follow up around four years. A total of 30 patients died or had sustained ventricular tachycardia. They were able to show that ve, vco2, slope, vo2 and qrs duration on resting ekg were able to independently predict event free survival. The cutoffs to detect an unfavorable outcome was a vo2 of less than 65 percent v evco2 slope of greater than 31 and qrs duration of greater than 170 milliseconds. Both of these graphs show that when these variables were paired together, they were able to demonstrate increased risk of events in their cohort. This study is often used to risk stratified patients prior to proceeding with pulmonary valve replacement. Thank you for listening to this talk. Please come visit us in cincinnati anytime.