CTCA and Functional Testing for Stable Chest Pain
CTCA and Functional Testing for Stable Chest Pain
We analysed data from August 2010 to April 2012 for patients who underwent CTCA for the investigation of chest pain after attending RACP or general cardiology clinics. There were 107 patients with moderate and high CAD scores. We also looked at 106 consecutive patients from April 2012 backwards who had undergone functional testing (DSE or MPS) and who attended these clinics. Inclusion criteria required patients to be in the moderate-to-high CAD score categories, as calculated by NICE guidelines 95. The choice of functional test in our hospital is down to the cardiologist's preference. Baseline demographic data were obtained retrospectively from clinical notes and electronic radiology and biochemistry results. Follow-up data were obtained from clinic letters. Hospital records were checked at six months for re-admissions and deaths. Baseline patient characteristics are summarised in Table 1.
Patients were beta-blocked by the referring clinician (atenolol 50 mg) and/or intravenously with metoprolol (5–30 mg) aiming to achieve a heart rate of <60 bpm. All patients received two 400 μg doses of sublingual glycerol trinitrate. All CTCA were performed with a 64-slice LightSpeed VCT XTe GE scanner (GE Healthcare) and prospective gating using the commercially available protocol (SnapShot Pulse, GE Healthcare) and the following scanning parameters: slice acquisition 64 × 0.625 mm, scan field of view (SFOV) cardiac, Z-axis detector coverage 40 mm, gantry rotation time of 350 ms. Patient's size was visually judged for adapted tube voltage; 100 kV was used for small patients, 120 kV for average size patients. Similarly, effective tube-current ranged between 500 mA and 650 mA based on patient's size judged visually. We only acquire the 75% phase or the RR-cycle. CTCA images were reconstructed with slice thickness of 0.625 mm, on an external workstation (ADW 4.5, GE Healthcare). Significant CAD on CTCA was defined as >50% diameter stenosis. The decision on further investigation was down to the cardiologist's judgment. ICA +/- proceed was chosen for the more proximal and severe stenosis.
All patients were scanned using a Philips IE33 echocardiography machine. The images were acquired by a trained cardiac physiologist with a consultant cardiologist reporting the scans. Intravenous dobutamine was administered via a syringe pump starting with 10 μg/kg/min and increased up to 40 μg/kg/min. Boluses of atropine up to a maximum of 1 mg were added if the target heart rate of 85% of maximum predicted was not achieved. Images were captured at rest, low-dose, pre-peak and peak heart rates. Sonovue contrast was used at the discretion of the cardiologist if the image quality was suboptimal.
Studies were performed under standard departmental protocols with a conventional gamma camera with sodium iodide detector and single photo emission computed tomography (SPECT) with technetium radiotracer. Images were acquired at rest and at stress, which was induced with adenosine intravenously at a rate of 140 μg/kg/min for six minutes with injection of radiotracer four minutes after the start of the infusion. All images were reviewed by a radiologist and a cardiologist.
Patients underwent ICA at King's College Hospital, and were all reviewed by a consultant interventional cardiologist. Severe CAD on ICA was defined as ≥70% diameter stenosis of at least one major epicardial artery. Functional analysis with fractional flow reserve (FFR) was used at the discretion of the interventional cardiologist before revascularisation.
A chi-squared test was used to compare the proportions of male/female patients, the presence of risk factors between the CTCA, DSE and MPS groups and the rate of revascularisations. For comparing the risk factors between the MPS, CTCA and DSE groups and the total sample an ANOVA test was used. A p value <0.05 was considered to indicate statistical significance.
Methods
Patients
We analysed data from August 2010 to April 2012 for patients who underwent CTCA for the investigation of chest pain after attending RACP or general cardiology clinics. There were 107 patients with moderate and high CAD scores. We also looked at 106 consecutive patients from April 2012 backwards who had undergone functional testing (DSE or MPS) and who attended these clinics. Inclusion criteria required patients to be in the moderate-to-high CAD score categories, as calculated by NICE guidelines 95. The choice of functional test in our hospital is down to the cardiologist's preference. Baseline demographic data were obtained retrospectively from clinical notes and electronic radiology and biochemistry results. Follow-up data were obtained from clinic letters. Hospital records were checked at six months for re-admissions and deaths. Baseline patient characteristics are summarised in Table 1.
CTCA
Patients were beta-blocked by the referring clinician (atenolol 50 mg) and/or intravenously with metoprolol (5–30 mg) aiming to achieve a heart rate of <60 bpm. All patients received two 400 μg doses of sublingual glycerol trinitrate. All CTCA were performed with a 64-slice LightSpeed VCT XTe GE scanner (GE Healthcare) and prospective gating using the commercially available protocol (SnapShot Pulse, GE Healthcare) and the following scanning parameters: slice acquisition 64 × 0.625 mm, scan field of view (SFOV) cardiac, Z-axis detector coverage 40 mm, gantry rotation time of 350 ms. Patient's size was visually judged for adapted tube voltage; 100 kV was used for small patients, 120 kV for average size patients. Similarly, effective tube-current ranged between 500 mA and 650 mA based on patient's size judged visually. We only acquire the 75% phase or the RR-cycle. CTCA images were reconstructed with slice thickness of 0.625 mm, on an external workstation (ADW 4.5, GE Healthcare). Significant CAD on CTCA was defined as >50% diameter stenosis. The decision on further investigation was down to the cardiologist's judgment. ICA +/- proceed was chosen for the more proximal and severe stenosis.
DSE
All patients were scanned using a Philips IE33 echocardiography machine. The images were acquired by a trained cardiac physiologist with a consultant cardiologist reporting the scans. Intravenous dobutamine was administered via a syringe pump starting with 10 μg/kg/min and increased up to 40 μg/kg/min. Boluses of atropine up to a maximum of 1 mg were added if the target heart rate of 85% of maximum predicted was not achieved. Images were captured at rest, low-dose, pre-peak and peak heart rates. Sonovue contrast was used at the discretion of the cardiologist if the image quality was suboptimal.
MPS
Studies were performed under standard departmental protocols with a conventional gamma camera with sodium iodide detector and single photo emission computed tomography (SPECT) with technetium radiotracer. Images were acquired at rest and at stress, which was induced with adenosine intravenously at a rate of 140 μg/kg/min for six minutes with injection of radiotracer four minutes after the start of the infusion. All images were reviewed by a radiologist and a cardiologist.
ICA
Patients underwent ICA at King's College Hospital, and were all reviewed by a consultant interventional cardiologist. Severe CAD on ICA was defined as ≥70% diameter stenosis of at least one major epicardial artery. Functional analysis with fractional flow reserve (FFR) was used at the discretion of the interventional cardiologist before revascularisation.
Statistical Analysis
A chi-squared test was used to compare the proportions of male/female patients, the presence of risk factors between the CTCA, DSE and MPS groups and the rate of revascularisations. For comparing the risk factors between the MPS, CTCA and DSE groups and the total sample an ANOVA test was used. A p value <0.05 was considered to indicate statistical significance.
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