The Study of Heart Disease

Background: Heart disease is the leading cause of death in the world according to the World Health Organization; Most morbidity and mortality from heart disease attributed to coronary heart disease (CHD), a disease characterized by a decrease in blood supply to the heart muscle caused by narrowing the internal width of one or more of the arteries that supply it with blood.

The symptoms are often related to situations where the oxygen demand increases and causes heart muscle ischemia. The most common symptom of myocardial ischemia is chest pain (also known as angina pectoris). In cases where the cause of the pain is unclear, and there is a low to moderate probability of myocardial ischemia, the patient will be referred for evaluation and understanding the reason for the formation of pain on exertion. Among the existing options, there is a stress echocardiography (SE) test and allows to detect of a change in the motility of the heart walls and thus assesses cardiac function at rest and exertion. For this test to be diagnostic, the patient must reach the target heart rate (at least 85% of the predicted maximum heart rate).

Sometimes there are situations where the subject does not reach the target heart rate for various reasons, or the imaging quality is low, and there is a limited ability of the test to produce an accurate coronary image. In these situations, it is customary to refer the subject for further imaging examination, such as Myocardial Perfusion Imaging (MPI) or Coronary Computed Tomography Angiography (CCTA).

Aim of the study: This study aimed to test the added value of performing additional imaging tests in patients with chest pain who did not reach the target heart rate, and the test did not show any signs of ischemia in the pulse obtained.

Methods: A retrospective cohort study included 830 subjects.

The sample is taken from the population of subjects who complaining of chest pains and underwent a SE at Soroka University Medical Center - in the Cardiology Department, in the period between May 2017 to April 2019, according to the inclusion criteria and divided into two equal groups - subjects who reached the target heart rate in this test compared to subjects who did not. The follow-up period defined as one year, from the date of this test, in which the frequency and findings of additional imaging tests performed and the clinical results that occurred such as Percutaneous Coronary Intervention (PCI) and/or Myocardial Infarction (MI) and bypass surgery and/or sudden cardiac death (SCD), during a follow-up year from the date of the test. The relevant information is taken from the "Clicks" and "Ofek" systems.

The data was processed and analyzed using IBM SPSS Statistics version 26 and EdrawMax version 10.0.6, which were also used to generate charts.

Results: A total of 101 additional imaging tests were performed (73 MPI tests and 28 CCTA tests), 35 diagnostic coronary angiography, and 9 PCI; There were no events of MI and/or SCD during the follow-up year.

Among the subjects who achieved the target heart rate, 28 additional imaging tests were performed after the SE test; Half of them were MPI tests. In contrast, among subjects who did not achieve the target heart rate, 73 additional imaging tests were performed; Most were MPI tests (n=59, p<0.001) while the rest were CCTA tests (n=14, p=0.25), it was also found that the number of coronary diagnostic catheterizations were performed in this group, was greater, compared to the subjects who achieved the target heart rate (n=30 different n=5, p<0.001), however, no statistically significant difference was found, between the groups, in the number of PCI performed (p=0.18).

Conclusions: The results of our study indicate that among subjects who underwent an SE due to a complaint of chest pain but did not achieve the target heart rate, the percentage of false-negative results leading to significant cardiac ischemia is tiny and within the acceptable range for this type of test, also in the population of subjects who reach the target heart rate.

These findings may contribute to the discussion regarding the sweeping recommendation of the exercise physiologist to perform additional imaging tests among these subjects, who did not achieve the target heart rate in the SE test and, on the other hand, did not show any decrease in left ventricular function during the test.

This study can be seen as a preliminary study, which can form the basis for future research such as conducting a multicenter study in order to obtain a richer and more comprehensive picture; Incorporating a qualitative methodology may also contribute to deepening and refining understanding regarding the considerations behind the decision to refer for further imaging tests.