Cardiopulmonary exercise stress testing can be useful in a variety of ways, particularly for Preventive Cardiology and Preventive Cardio-oncology. The test helps to assess for levels of fitness, causes of functional limitation, and evidence of ischemia. Test results can be used to counsel individuals, guide exercise prescriptions, and reassure, encourage, and motivate individuals for lifestyle modification and behavior change.
The exercise ECG portion of the test gives information regarding evidence of ischemia, exercise capacity, and adequacy of heart rate response, and response of blood pressure to exercise. The information of this portion of the test can help to determine whether there are any high-risk cardiac features that need to be addressed, such as evidence of ischemia or hypotensive response to exercise. Limited heart rate response is also useful to help determine whether rate-limiting medications or pacemaker settings need to be adjusted. Often, when medications like metoprolol or pacemaker heart rate response are adjusted, this can improve the function and experience of patients who are previously limited by their heart rate during activity. The exercise capacity information given by the exercise ECG, such as excellent, good, average, below average, fair, or poor can give an indication of individuals’ ability to meaningfully, safely, and successfully pursue exercise. Oftentimes, some patients who have had prior cardiovascular events may shy away from moderate or intense exercise for fear of cardiovascular injury as a result of exertion. Pursuing an exercise ECG portion of the cardiopulmonary stress test can help individuals in such cases recognize that they can perform moderate or intense exercise safely without injuring their heart. The exercise capacity reported on the test can help these individuals see that their exercise or aerobic capacity is poor because of their hesitation to pursue moderate or intense exercise. This can be motivating for individuals to recognize that they can benefit from doing more and that they can do more safely. This is particularly the case for individuals who have experienced a cardiovascular event from spontaneous coronary artery dissection, which does not have many modifiable risk factors, and understandably leads to apprehension in young women diagnosed with this condition. However, the exercise ECG portion alone lacks several informative parameters important for patient care in Preventive Cardiology and Cardio-Oncology.
The specific addition to the test provided by the ‘cardiopulmonary’ portion involves oxygen consumption. If oxygen consumption (or VO2) is below average, limited, or poor, there can be several reasons for this. The most common reasons include cardiac impairment, pulmonary impairment, deconditioning, excess weight, and limited heart rate reserve. There are various parameters in the cardiopulmonary stress test results that will indicate whether deconditioning plays a role, whether BMI plays a role, whether cardiac impairment plays a role (in which case this could be due to low flow from systolic dysfunction or due to diastolic dysfunction or even heart rate), or whether pulmonary impairment plays a role (which could be of varied etiology). This addition to the test also helps patients to objectively see data supporting the suspicion that they have become deconditioned after a cardiovascular event or after cancer therapies. They get to see that the cancer therapies or their subsequent levels of activity following their cardiovascular event could currently or potentially affect their function, and may explain any current functional limitation or in fact set them up for functional limitation going forward. The test can also help patients see the effect of any excess weight on their compromised oxygen consumption. Given that cancer therapies for breast cancer, for example, will often include radiation, surgery, and chemotherapy that can injure the heart and/or the lungs, it is helpful to determine the suggested underlying causes of functional limitation as assessed by oxygen consumption in these patients who have had treatment involving the chest. Performing the cardiopulmonary stress test at baseline before treatment helps individuals see their level of fitness, deconditioning, weight effect, cardiac impairment, or pulmonary impairment, even before ever undergoing cancer therapy. Given that fitness levels and injuries to the heart or the lungs can be affected by cancer therapies, then repeating the test after therapies can show patients the change that has occurred as a response to therapies. This can be helpful for patient to have a sense of their original baseline and goals that they can work towards to supersede even that baseline. For individuals who are not going to undergo cancer therapies, obtaining a baseline also helps individuals with a sense of how much they could potentially achieve. Then, once they have achieved a particular goal, the test can be repeated to show the improvement and continue to inspire motivation. This objective collection of evidence and data that can be used for motivation, reassurance, counseling, and exercise prescription is all key for lifestyle modification and behavior change in Preventive Cardiology and Preventive Cardio-Oncology. Thus, for all these reasons and more cardiopulmonary stress testing will evolve to play a large role in Cardio-Oncology prehabilitation, habilitation, and rehabilitation1,2,3, as we help individuals prepare for, experience well, and long outlive their cancer therapies.
References
- https://earlycareervoice.professional.heart.org/preventive-cardio-oncology-the-rise-of-prehabilitation/. Accessed April 20, 2019.
- Squires RW, Shultz AM, Herrmann J. Exercise Training and Cardiovascular Health in Cancer Patients. Curr Oncol Rep. 2018 Mar 10;20(3):27. doi: 10.1007/s11912-018-0681-2.
- Gilchrist SC, Barac A, Ades PA, Alfano CM, Franklin BA, Jones LW, La Gerche A, Ligibel JA, Lopez G, Madan K, Oeffinger KC, Salamone J, Scott JM, Squires RW, Thomas RJ, Treat-Jacobson DJ, Wright JS; American Heart Association Exercise, Cardiac Rehabilitation, and Secondary Prevention Committee of the Council on Clinical Cardiology; Council on Cardiovascular and Stroke Nursing; and Council on Peripheral Vascular Disease. Cardio-Oncology Rehabilitation to Manage Cardiovascular Outcomes in Cancer Patients and Survivors: A Scientific Statement from the American Heart Association. Circulation. 2019 Apr 8:CIR0000000000000679. doi: 10.1161/CIR.0000000000000679. [Epub ahead of print].