CT Calcium Scoring in Suspected Stable Angina
Condition: Coronary Disease
MeSH terms: Coronary Disease; Coronary Artery Disease
Study type: Observational

Summary: 
      Patients with stable chest pain presenting to general practitioners in UK are routinely
      referred to the chest pain clinics in the hospitals. They are assessed by clinical history
      including risk factors, cardiovascular exam, resting ECG, chest x-ray, and exercise ECG. CT
      calcium scoring (CTCS) is a technique that is very sensitive in identifying and quantifying
      calcified atherosclerotic plaques. Recent guidance from the National Institute of Clinical
      Excellence (NICE, citation 1) proposes the use of CTCS in patients with stable chest pain who
      have low likelihood of coronary artery disease (CAD). They recommend that patients with low
      likelihood (10-30%) have a CTCS and if the score is 0, they can be considered to have
      non-cardiac chest pain. However, there is controversy regarding relationship of absent
      calcification with significant CAD and its prognostic value.

      At our institution, we have been performing CTCS in this patient cohort since 2003. We plan
      to retrospectively review the usefulness in CTCS in patients with different likelihood for
      significant CAD, particularly in patients with absent calcium and compare with the
      traditional assessment. We also plan to follow-up these patients for any myocardial
      infarction and death from any cause.
    

Detailed description: 
      The study seeks to determine the usefulness of CT calcium scoring (CTCS) in patients
      presenting with non-acute chest pain to the rapid access chest pain clinic (RACPC) and
      compare it with the traditional assessment in predicting significant CAD and outcome with
      respect to non-fatal MI or death. The clinical, diagnostic, and follow-up data of patients in
      last 7 years since CTCS has been performed in the hospital would be retrospectively analysed
      for the purpose.

      Background Patients with chest pain (excluding that of sudden onset) are routinely referred
      by the GPs to the RACPC centres in the hospitals. They are assessed by clinical history
      including risk factors, cardiovascular exam, resting ECG, chest x-ray, and exercise ECG. At
      our institution, we have also been performing CTCS in men more than 40 and women more than 50
      years of age since 2003. Recent NICE guidance1 recommends that patients with low pre-test
      probability (10-30%) of significant coronary artery disease (CAD) have a CT calcium scoring
      scan and if the score is 0, they can be considered to have non-cardiac chest pain. However,
      there is controversy regarding relationship of absent calcification with significant CAD and
      its prognostic value.

      This study would enable us to compare and determine the value of CTCS in patients with
      non-acute chest pain in predicting significant CAD and safety of absent coronary artery
      calcification.

      Rationale for Study

        1. To determine if CT coronary calcium scoring adds any value to the existing clinical
           assessment and exercise ECG. This is not well established in patients presenting with
           non-acute chest pain to the rapid access chest pain clinics.

        2. The study would help in determining if absence of calcification on CT can be considered
           to have low likelihood of significant coronary artery disease and a good cardiovascular
           outcome over the period of follow-up. Both these issues are currently controversial in
           the literature in this group of patients.

      STUDY OBJECTIVES

      Primary Objective To determine the prognostic value of CT coronary calcium scoring in
      patients with non-acute chest pain for non-fatal MI and death, and compare with traditional
      assessment including exercise ECG.

      Secondary Objectives To determine how CT coronary calcium scoring compare with traditional
      assessment including exercise ECG in predicting significant coronary artery disease in
      patients presenting with non-acute chest pain.

      METHODOLOGY Design This is a retrospective cross-sectional study involving analysis of
      patients' clinical, diagnostic, and management data from hospital records and follow-up
      questionnaires for outcome. The study does not require any new diagnostic, therapeutic, or
      interventional procedure.

      Data of patients who have presented to the chest pain clinic since October 2003 would be
      collected from hospital records for:

        1. Age, sex, type of chest pain, and risk factors. These would be used to calculate the
           pre-test probability of significant coronary artery disease (CAD) using Duke's score.

        2. Results of exercise ECG where performed.

        3. Results of CT calcium scoring.

        4. Results of other non-invasive investigations such as stress imaging and CT coronary
           angiography where performed.

        5. Results of invasive coronary angiography where performed. Patients with >70% diameter
           stenosis or those who underwent percutaneous stent insertion (PCI) or bypass surgery
           would be considered to have significant CAD.

      For those patients who do not undergo any PCI or surgery as a result of above evaluation, we
      will try to find out if they have subsequently suffered any heart attack or died. This would
      again be performed through hospital records and if not available, through questionnaires send
      to the patients and/or their GPs as part of standard clinical care.
    

Intervention name(s): CT calcium scoring
Intervention type(s): Other
Intervention description(s): CT Calcium scoring was performed in the patients as an imaging test in addition to the traditional assessment on the same day of patients attending the chest pain clinic on the first visit. This was performed with standard protocol and the absolute calcium score was calculated.
Intervention MeSH terms: Calcium
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients who presented to our chest pain clinic between October 2003 to March 2010 with
        stable (non-acute) chest pain and assessed with history, physical examination,
        cardiovascular risk factors, chest X-ray, 12-lead resting ECG and exercise ECG.
      
Keywords: coronary disease; tomography, x-ray computed; calcium; exercise test