Multi-Slice CT for Coronary Calcium Scoring and Coronary Angiography Gunjan Gholkar MD Metro Heart and Vascular

Objectives Show lots of pretty pictures Raise awareness of current indications and clinical scenarios for which to consider CT angiography Interpretation of reports Review strengths and limitations of MSCT

Pretest Probability Diamond – Forrester Duke clinical score

Test Selection According to Pretest Probability of CAD

Indications of Coronary CTA Ruling out significant luminal stenoses in stable patients with suspected coronary stenoses, but intermediate pretest likelihood of disease High negative predictive value and thus allows one to reliably rule out presence of coronary stenosis. Aim is to avoid unnecessary invasive testing Most useful in low to intermediate risk High false positive rate in very low risk patients. Sensitivity decreases in very high pretest probability patients.

Indications of Coronary CTA Ruling out coronary artery disease in acute chest pain ER patients with normal enzymes , ekg and low likelihood of CAD. Patient with new LBBB

Special situations- Emergency department chest pain >60% ED chest pain is noncardiac. Numerous studies Show high NPV 97-100% Show poor PPV 47-52% Versus nuclear imaging is faster/cheaper/less repeat presentations.

Indications of Coronary CTA 3. Equivocal stress test or persistent symptoms despite negative stress test

Indications (Contd.) Prior to non-coronary cardiac surgery (valve or congenital repair) Evaluation of coronary artery disease in new onset heart failure. Suspected coronary anomalies Cardiac transplant evaluation Determine patency of bypass grafts

Case 1 43 year old man commenced a new exercise program Left side chest discomfort on exertion Cholesterol 6.0, LDL 3.6, HDL 1.3 No smoking, diabetes, HT or family history of IHD BMI 26 kg/m2 Medications – none Resting ECG – normal What next ?

Functional Test Objectively negative stress echocardiogram – 13 minutes However, vague left sided chest pain at peak exercise “Is my heart OK ?”

LAD CIA Mar 08

Indications (Contd.) Patients to undergo electrophysiologic intervention (AF ablation, BiV pacing) Aortic diseases Pericardial disease Congenital heart diseases

Aortic Coarctation Visualized by 16-Row Detector MSCT Fröhlich, G et al. Circulation. 2005;112:e81.

Pulmonary Vein Stenosis Vasamreddy et al. Heart Rhythm (2004) 1, 78-81.

Pericardial Calcification Multi-Slice CT Scanning Superior to MRI Hoffmann et al. Circulation 108 (7): 48e Figure IG1

Left Main Arising from right Cusp

The Great Promise of MSCT The “Triple Rule-Out”

Normal coronary arteries

Tight LAD stenosis

Indications (Contd.) Assessment of complex congenital heart disease especially in regards to both coronary/great vessels and cardiac chambers and valves.

Surgical planning The use of MDCT in surgical planning before cardiothoracic surgery, particularly for reoperations, is increasingly recognized. Preoperative scans can evaluate the proximity of mediastinal structures to the sternum( i.e. aorta, right ventricle, bypass grafts); the degree of aortic calcification( i.e. to guide cannulation sites); and concomitantly provide information about cardiac morphology( e.g. presence of a ventricular aneurysm). Ongoing studies are evaluating whether this added information might reduce intraoperative and perioperative complications.

Special Situations- Coronary Stents Core 64 trial showed PPV 57% and NPV 80% if stent < 3.0mm If left main stent > 4.0mm is 98% accurate Routine use of CTCA for instent restenosis is NOT recommended.

Cardiac morphology/function Contrast enhanced MDCT can provide high resolution morphologic images of cardiac chambers. It can also provide accurate assessment of right and left ventricular systolic function. Other imaging modalities such as echocardiography , MRI which do not require radiation exposure are preferred for cardiac morphology.

Inappropriate indications Asymptomatic patients High pretest probability including positive stress tests. Positive cardiac enzymes or ST elevation on ECG. Instent evaluation especially stents < 3.0 mm.

Contraindications

Relative contraindications

Case 2 48 yr old man Consistent exertional bilateral arm tightness “like the compression of a blood pressure cuff” Hyperlipidemia. Father and brother IHD in their 50s. On no medical therapy at time of presentation Negative Stress Echo after 12 minutes of Bruce protocol. No symptoms with stress test Worrying symptoms and CV risk factors, but negative functional test

Outcome This patient had a concerning history and risk factor profile. He declined the offer of an invasive angiogram given his negative stress test. He agreed to have a CT coronary angiogram which detected severe proximal LAD disease which required revascularisation.

Volume rendered image of Coronary CT Severe LAD and Diagonal branch stenosis

Coronary artery calcium scoring

Coronary Calcification Proven robust technique in identifying at risk population Coronary Calcium Score >100 or >75th pecentile identifies a CAD equivalent Coronary Calcium scores are given in all patients undergoing CTA except graft patients and some stent patients.

Diagnostic accuracy CTCA vs Invasive coronary angiography Visualize wall in addition to lumen ICA may not detect positive remodeling and underestimate plaque burden

2010 ACCF/AHA Guidelines for assessment of cardiovascular risk in asymptomatic adults.

Clinical applications

The Calcium Scale 1–99 mild 100–400 moderate >400 severe The calcium scale is a linear scale with 4 calcium score categories: 0 none 1–99 mild 100–400 moderate >400 severe

Interpretation of CTA Calcium score Severity of stenosis and coronary segments. Type of plaque Non-cardiac findings

Recommended Quantitative Stenosis Grading 0 Normal: Absence of plaque and no luminal stenosis 1 Minimal: Plaque with <25% stenosis 2 Mild: 25%–49% stenosis 3 Moderate: 50%–69% stenosis 4 Severe: 70%–99% stenosis 5 Occluded

CTA Limitations Rapid (>80 bpm) and irregular HR High calcium scores (>800-1000) Stents Contrast requirements (Cr > 2.0 mg/dl) Small vessels (<1.5 mm) and collaterals Obese and uncooperative patients RADIATION EXPOSURE

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