Practical significance of exercise stress test in individuals at low risk for atherosclerotic coronary artery disease

Sanjeev V Mangrulkar; Pramod Katare; Ashiwini Joshi

doi:10.4103/astrocyte.astrocyte_8_17

ORIGINAL CONTRIBUTION - CLINICS IN PREVENTIVE CARDIOLOGY

Year : 2017 | Volume : 3 | Issue : 4 | Page : 196-200

Practical significance of exercise stress test in individuals at low risk for atherosclerotic coronary artery disease

Sanjeev V Mangrulkar, Pramod Katare, Ashiwini Joshi
Department of Medicine, Deenanath Mangeshkar Hospital and Research Center, Pune, Maharashtra, India

Date of Web Publication

7-Jul-2017

Correspondence Address:
Sanjeev V Mangrulkar
Department of Medicine, Deenanath Mangeshkar Hospital and Research Center, Pune, Maharashtra
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/astrocyte.astrocyte_8_17

Abstract

Background: Despite not finding favor with a number of apex global bodies including the American Heart Association, American College of Cardiology, United States Preventive Services Task Force, exercise stress test continues to be performed customarily among asymptomatic individuals to screen for potential presence of ischemic heart disease. Materials and Methods: This retrospective study comprises a successive total of 2042 individuals who were put through a screening stress test as a part of their health checkup package. A telephonic communication was made with all the persons who had been advised further assessment such as repeat stress test, drug therapy, stress thallium testing, or coronary angiography. The compliance of this group to the advice offered was noted along with their subjective sense of satisfaction with the overall process. Based on these inputs the practical utility of stress test was calculated as either good or poor. Results: Out of 2042 individuals who underwent stress test, 183 (9%) were reported as positive. Out of these 183 individuals only 132 with positive stress test could be contacted telephonically. After a detailed analysis of their compliance with the advice offered, it was noted that the screening had best practical utility when the test report was negative. Only one person with a positive report had followed the advice to the logical end by undergoing coronary artery bypass grafting and had a likely good practical utility. In rest of the scenarios, the practical utility was poor. Conclusion: The screening exercise stress tests are sought by most individuals as means of reassurance about health. Its practical significance in all other scenarios is poor. Therefore, unless definite indications exist, stress test should not be performed as a screening test.

Keywords: Atherosclerotic heart disease, exercise stress test, myocardial ischemia screening test, silent myocardial ischemia

How to cite this article:
Mangrulkar SV, Katare P, Joshi A. Practical significance of exercise stress test in individuals at low risk for atherosclerotic coronary artery disease. Astrocyte 2017;3:196-200

How to cite this URL:
Mangrulkar SV, Katare P, Joshi A. Practical significance of exercise stress test in individuals at low risk for atherosclerotic coronary artery disease. Astrocyte [serial online] 2017 [cited 2023 Jun 4];3:196-200. Available from: http://www.astrocyte.in/text.asp?2017/3/4/196/209933

Introduction

Since a long time, exercise stress test has been taken as a useful diagnostic test to screen for ischemic heart disease (IHD). Often performed to evaluate for fitness among asymptomatic individuals, it is carried out as part of annual executive health checkup, prerequisite to employment and fresh insurance policy, and, as a part of follow-up examination following invasive coronary management. This customary practice of screening low-risk individuals with stress test has, however, never found favor with a number of apex global bodies including the American Heart Association (AHA),^[1] American College of Cardiology (ACC),^[1] United States Preventive Services Task Force,^[2] and a host of other researchers.^[3] This retrospective study dwells upon identifying the practical significance of screening stress test among asymptomatic individuals at low risk for IHD.

Materials and Methods

Conducted at Deenanath Mangeshkar Hospital, a tertiary care institution in Pune, this retrospective study comprises a total of 2042 successive individuals who had no cardiac symptoms and were referred for a screening stress test as a part of their healthcare package. All patients who had undergone the test for a valid cardiac indication were excluded from the study. Demographic parameters and the results of the tests were noted for all patients included in the study. The reporting was done by the performers of the tests, consisting of senior physicians of the hospital. The stress test reports were accepted as unchanged to avoid personal bias of the investigators in the matter.

The stress test results were classified in subgroups such as:

(The stress test reports were classified into various groups. The stress test results such as negative, false positive, etc. represent how the physicians have interpreted it and may not have true scientific meaning attached to it.)

Negative
False positive – when the physician with his personal experience felt the test to be negative though it looked apparently positive
Borderline positive – when the ECG changes were not enough and/or there was no angina
Positive – it was further subgrouped as

Technically positive – when the physician felt that post exercise ST/T changes on ECG were significantly positive but the person did not have angina or the changes were too transient showing rapid reversal and the person had low overall risk for IHD
True positive – where the stress test fulfilled all the criteria for positivity.

All individuals whose stress test report was positive were contacted telephonically. The advice offered to them was noted. An oral consent was obtained from them in a prescribed format of discussion. No communication was made to individuals with negative, false positive, or borderline positive results, since it was known from the records that a uniform advice of 'no-intervention' had been offered to them. During the telephonic enquiry, a note was made regarding any relevant medical events that had followed during the intervening period, compliance of the advice offered, or if any medical action other than the advice offered was undertaken in consultation with some other physician. Patients' overall impression about the entire process of stress test was noted, including their sense of fulfillment, sense of dejection, sense of gratitude or futility, etc.

Based on the above observations, practical significance of the test was calculated on three parameters:

Overall subjective feeling of the person who had undergone stress test, his/her sense of having fulfilled whatever objective he/she had in performing the test; sense of fulfillment, sense of dejection, etc.
Follow-up of the advice to its logical conclusion, such as any new test done or intervention done as per advice
Assessment of academic quality of advice offered based on ACC/AHA criteria.

The practical significance of the test was best when an academically sound advice had been given and followed to its logical end along with a sense of satisfaction to the performer. Any other result was poor practical utility. This included cases where the advice was not followed, when the advice did not match ACC/AHA criteria of management or the performer was dissatisfied with the entire process.

Results

The distribution of the test reports is given in [Table 1].

Table 1: Frequency distribution of various reports of stress test

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Out of the total of 2042 candidates undergoing stress test barring the 183 (9%) cases which were reported positive, rest were reported as either negative, borderline positive, false positive, or inconclusive (total 91%) in whom no further action was advised [Table 1].

An attempt was made to contact all 184 persons with positive stress test report but we failed to contact or get information from 51 among these. Their phone numbers were either not reachable, were wrong, or were not picked up and some refused to give consent for sharing their information. This left us with a total of 132 individuals with positive stress test out of total 2043 cases who underwent stress test. The advice offered to these and their compliance is presented in [Table 2].

Table 2: Type of advice offered to individuals with positive stress test along with compliance

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Among the 106 patients that were reassured, 104 felt satisfied with the reassurance, while two were not; they took independent consultations from their physicians and were finally reassured by their physicians. Four individuals who were referred to cardiologist followed the advice and were cleared by the cardiologists as normal stress tests requiring no further action. While, one of these four patients was advised medical treatment with aspirin and atorvastatin.

Two patients underwent thallium scans, which were reported as negative for inducible ischemia, following which both were given clearance and no further follow-up advised.

Five patients were advised coronary angiography (CAG). Two patients refused to undergo CAG. Out of the three patients who underwent CAG, two were reported normal and one had triple vessel disease (TVD) for which he was advised coronary artery bypass grafting (CABG) surgery, which he underwent at a later date.

An opinion was also sought during the telephone conversation regarding the subjective feeling about the whole procedure of getting a screening test done. Most patients did not have any strong feeling about the entire issue. Two patients were very dissatisfied with the process, since they had to seek multiple cardiological opinions before getting a clearance regarding their cardiac status. Both felt that the entire exercise was wasteful; timewise, moneywise, giving a lot of emotional and mental stress. It was assumed that entire group with negative stress test report must have been satisfied with the overall process of stress test. They had not been advised any further intervention which must have reassured them about their health.

The only one person, who had undergone bypass surgery, was overwhelmingly happy and had a feeling that it was only because of this test that an occult, potentially lethal heart problem could be diagnosed and treated well in time.

Discussion

The aim of this study was to find out the practical significance of the stress test when used as a screening test in general population. The concept of practical significance had to be specifically devised for this purpose. In common practice stress tests as a part of screening tests are not done as per strict academic recommendations; therefore, their clinical utility is expected to be low. The fact that these tests are still done in large numbers led us to believe that there must be a practical significance beyond clinical utility in performance of these tests. Many a time, these tests are performed because of patient's anxiousness to be reassured about his health status, or due to peer pressure. Performed in these settings stress test ceases to be a medical diagnostic test and becomes more as a saleable commodity subject to market-related parameters, wherein consumer satisfaction becomes a driving force behind their commercial success. This study tries to find out consumer satisfaction in getting this test done. Since this was a health-related issue, it would have been improper to do away with clinical utility altogether. Hence performer's perception of the test and clinical utility were compounded to estimate what we call as the 'practical significance' of this test. We assume that the practical significance of this test could be best when a clinically appropriate advice was given which was followed to its logical conclusion and along with thorough satisfaction to the performer of the test. An advice which does not fulfill all these criteria is considered to have poor practical utility.

Based on these parameters, the practical utility can be calculated for individual cases. All the cases can be grouped on the basis of advice offered to them since the satisfaction index is likely to be similar toward a particular advice offered.

Subgroup 1 (Negative stress test, Reassurance offered): This was the largest group (n = 1785). The analysis of this group is presumptive since no personal communication was made or felt necessary and it was known that all the individuals in this subgroup were offered an assurance that their hearts were healthy with no need for further intervention. The patient satisfaction index must have been highest for this group, since this gives them a certification of 'Good Heart' and ratifies their current lifestyle for at least one or more years depending upon the frequency at which these persons undergo repeat checkup. This was rated as the best practical significance of stress test, as there is good patient satisfaction and the advice too is likely to be academically correct; however, there are two points against it:
1. The advice tends to overlook some infrequent false negative test results. Dr. Aboukhoudir et al.^[4] have reported one such case where a critical left main coronary stenosis was totally missed during a stress test. Negative predictive value (NPV) of stress test may be as high as 99.3%. The false negative cases were noted through the frequency of cardiac events, angiography studies in the patients who were reported to have normal stress tests.^[5] This study was limited to locating such events through telephonic communication retrospectively. There was no standardized prospective protocol of doing angiographic evaluation in all persons even though the stress test was negative. Comparing it with the present study, 99.3% NPV would mean that about 14 individuals with occult ischemia out of 2043 individuals may be missed, giving them a false sense of satisfaction. A study in which negative test results had been confirmed by angiography could not be found. An individual with negative stress test would unlikely be willing to undertake CAG evaluation for confirmation. It is very difficult to undertake such studies because of verification bias
2. The negative stress test result is unlikely to promote positive health directives in concerned individuals. The sense of satisfaction from negative stress test result may in fact strengthen their belief in current lifestyle, hence a smoker may continue with his smoking; a sedentary person in unlikely to take up to exercise. Physician's aim to promote healthy way of life through such periodic health checkups may not be achieved

Subgroup 2 (Technically/Borderline/False positive, Reassured): These three groups have been taken together (n = 112) for purpose of analysis since the interpretation logic and advice offered are the same for this group. Given the overall low risk of IHD in this group, all such reports were treated as negative for advice and were offered only reassurance. Statistically this could be a good advice but the negative points mentioned for Subgroup 1 remain valid for this group also. The patient satisfaction index, however, may not be all that good for this group, as this report leaves some unpleasant doubts in the mind of the individual. He may seek multiple opinions and have to undergo further investigations, which might be unrewarding and lead to untoward financial and psychological consequences. This would mark low practical significance for the test. In this study, there were two such persons who were dissatisfied with their stress test result and had to seek multiple opinions to be reassured
Subgroup 3 (Technical/Borderline/False positive, Medicines started): This group (n = 1) is difficult to categorize. The advice may not be academically sound, since the risk of IHD is low and hence the use of medicines such as antiplatelet agents or lipid lowering agents may be unwarranted. Such advice may expose the individual to the side effects of medicines. Patient satisfaction index in this group is likely to be low and it has all the negative points mentioned in Subgroup 2, that too on a higher scale. This would mark poor practical significance of the test
Subgroup 4 (Repeat stress test): This group comprised 14 individuals who were advised to undergo repeat stress test out of which only four complied. Repetition of stress test in all four did not alter the advice, which remained conservative. Poor compliance for this advice might be due to a sense of frustration and loss of faith in the utility of the test itself on the part of individual. This indicates poor satisfaction index for the patient and no gain for the person in terms of management, hence poor practical significance of the test
Subgroup 5 (Positive, workup advised): This is the smallest of the group. This group had seven individuals with positive test report who were advised further invasive workup in the form of Thallium scan (n = 2) and CAG (n = 5). Both the thallium scans were reported as normal, thus giving clean chit to both. However, the cost for the result was high, both financially as well as due to inordinate exposure to radiation, a risk that is hardly perceived by the person himself. This would reduce the practical and clinical significance of this approach to poor level, especially by sheer statistical wisdom since this negativity ought to have been a foregone conclusion.

Of the five persons who were advised CAG, only two complied. This is a remarkable observation. All the three persons who refused to undergo the CAG, chose not to follow-up the issue any further and expressed satisfaction for not having done anything further. None of them had any medical event in the intervening period which was more than a year post test and this they considered as a proof that their decision was correct. This behavior highlights the mindset of some persons undergoing the stress test. As many of individuals undergo this test just to confirm the normalcy of their heart, an unexpected abnormal stress test report may not be enough to convince them to undergo further costly and invasive tests. Compliance of a medical advice depends upon the perceived threat of a disease by an individual. For many persons who undertake this test for no specific indication, the anticipated disease-related risk is low. Hence an advice for invasive workup may be. The practical significance of such a test result is obviously very low.

Of the two persons who underwent CAG, one had normal coronaries. Given the enormous economic cost of the test along with it being an invasive test, an obvious normal report could be perceived as a poor buy. Thus, the practical significance of the test would be poor. Second patient who underwent CAG was found to have TVD for which CABG was advised and undertaken. The patient satisfaction index was quite good for this patient. Since the CAG showed advanced TVD, the advice of CABG is justifiable, though the data to support such invasive approach are sparse. In this study, it has been rated as good test result and good practical significance.

Thus, from the analysis of all the subgroups one can see that practical significance of the screening stress test is limited to two sets of individuals:

Largest group of individuals with low risk for IHD who undergo this test have just to be reassured about their health and in whom the test result is definite negative. These individuals are only reassured. This might be the sole reason why this test has been successful so far. However, there is always risk of missing out few false negative cases. There is another downside as this does not help in building up of good health-related practices. In a strict academic sense, this entire exercise of trying to prove what is obvious seems unwarranted
A very small group of individuals in whom a genuine occult ischemic process is diagnosed and managed before it develops into an emergency. This group being very small, hence management would not be considered as cost-effective. This may give rise to academic criticism.

Conclusion

This study clearly establishes that unless definite indications exist, stress test should not be performed as a screening test. Although this could unearth very few cases of occult ischemia requiring invasive treatment, however, these would be rare; thus devoid of statistical and economic wisdom. There is also likelihood of missing out few false negative cases which may negatively impact induction of healthy lifestyle in some individuals.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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