{
  "abstract": "Background Ischaemic heart disease (IHD) is the leading cause of death and morbidity. Stress echocardiography (SE) is an established non-invasive test for the diagnosis and assessment of IHD. Patients who are unable to achieve target heart rate via exercise have an inconclusive test, whilst some patients experience side effects from the use of pharmacological agents dobutamine and atropine. There is a need for strategies to mitigate the risk of side effects while ensuring target heart rate is achieved and these strategies need to have no effect on the accuracy of stress testing when compared to the conventional methods. Studies have shown that mathematics can have a sympathomimetic effect on people causing an increase their heart rate (HR). We therefore tested this as an option for use in stress echocardiography.Methods Ninety-five patients having SE were involved in this study. Forty-five had maths used as stressor to achieve target heart rate. A baseline HR was recorded at rest and then a maths question was introduced asking the patient to subtract their age from 220 and then to calculate 85% from that answer. Data was collected on the increase in HR following maths and on the dose of dobutamine and/or atropine given. The other 50 patients did not have maths and received the standard of care. There was 4.3% (n=2) inconclusive rate in the maths group and 4% (n=2) in the non-maths group. Inconclusive tests were excluded from calculations of specificity, sensitivity and accuracy but were included in HR assessment.Results The data showed a wide range of change in HR with maths [0–25beats per minute(bpm)]. Median increase in HR observed prior to stress testing was 6 [Interquartile range 2–10bpm]. There was no significant difference in the use of dobutamine and atropine between both groups. Accuracy of stress echocardiography was assessed based on significant coronary stenoses in patients who had cardiac catheterisation. Further, to overcome potential bias of patients with negative SE not getting cardiac catheterisation, the patients were followed up over a 3-year period for adverse cardiovascular outcome. There were no deaths known to the investigators attributable to cardiovascular events. The sensitivity, specificity and accuracy of stress echo was the same at 1,2 and 3 years in both groups. Variation between groups is as follows: Sensitivity 92.3%, specificity 100%, positive predictive value 100%, negative predictive value 96.7% and accuracy 97.6% with maths vs. sensitivity 85.7%%, specificity 97.1%, positive predictive value 92.3%, negative predictive value 94.3% and accuracy 93.8% without maths.Conclusion Maths as a stressor can cause a substantial increase in the heart rate, up to 25 beats per minute. There was no significant reduction in the use of dobutamine and atropine. The use of maths does not adversely affect the accuracy of stress echocardiography which has a very high negative predictive value and overall accuracy even at 3 years.",
  "authors": [
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "J Lodge"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "A Abdullah"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "J Pradhan"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "MF Raja"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "M Hilal-Babu"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "O Assaf"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "R Argyle"
    },
    {
      "affiliations": [
        "Lancashire Cardiac Centre, Blackpool Teaching Hospitals NHS Foundation Trust"
      ],
      "name": "KYK Wong"
    }
  ],
  "title": "6-014 Mathematics helps increase heart rate for stress echocardiography",
  "uid": "a43d06a8-c459-57af-a754-4fadeac2134b"
}