Cardiothoracic Surgery · Supplementary · from Cardiothoracic Surgery

Case 2: Coronary Artery Bypass Grafting

Patient Presentation

Demographics: 58-year-old male construction company owner

Chief Complaint: "I had a heart attack 2 weeks ago, and the cardiologist says I need bypass surgery because stents won't work for my blockages."

History of Present Illness: Mr. S.B. presented to the emergency department 2 weeks ago with acute onset crushing substernal chest pain radiating to his left arm and jaw, diaphoresis, and nausea. ECG showed ST elevation in leads V1-V4 and he was taken emergently for primary PCI. Angiography revealed a thrombotic occlusion of the mid-LAD (culprit lesion), which was stented (drug-eluting stent) with restoration of TIMI 3 flow. However, significant additional disease was identified: 80% stenosis of the proximal LAD (upstream of stent), 90% ostial circumflex stenosis, 85% stenosis of the first obtuse marginal branch, 75% stenosis of the proximal RCA, and 70% distal RCA stenosis (SYNTAX score: 33 — high).

The interventional cardiologist and Heart Team recommended surgical revascularization (CABG) for the non-culprit disease given the high SYNTAX score, left main equivalent disease pattern, diabetes mellitus, and complexity of the lesions. Mr. S.B. was stabilized medically and now presents to the cardiothoracic surgery clinic for pre-operative evaluation.

He reports no recurrent chest pain since the MI and PCI. He is anxious about surgery, particularly about the sternotomy and recovery time. He needs to return to work as his business depends on his active involvement.

Past Medical History:

• Acute anterior STEMI (2 weeks ago — treated with primary PCI to mid-LAD)
• Type 2 diabetes mellitus (15 years, on insulin)
• Hypertension (20 years)
• Hyperlipidemia
• Obesity
• Peripheral arterial disease (ABI 0.72 bilaterally, intermittent claudication)
• Obstructive sleep apnea (on CPAP)
• Former smoker (35 pack-years, quit 2 years ago)

Medications:

• Aspirin 81 mg daily
• Ticagrelor 90 mg BID (post-PCI — will be held pre-CABG)
• Atorvastatin 80 mg daily
• Metoprolol succinate 100 mg daily
• Lisinopril 20 mg daily
• Insulin glargine 32 units nightly
• Insulin lispro sliding scale with meals
• Eplerenone 25 mg daily (post-MI with reduced EF)

Social History:

• Former smoker: 35 pack-years (quit 2 years ago)
• Rare alcohol
• Married, 3 children (youngest age 16)
• Owns and operates construction company — physically demanding oversight role
• Uses CPAP nightly for OSA (AHI 32 pre-CPAP)
• High-stress lifestyle; minimal regular exercise prior to MI

Family History:

• Father: MI at age 52 (survived, died of CHF age 71)
• Mother: type 2 diabetes, died of stroke age 68
• Two brothers: both with CAD (one with prior CABG age 55)

Physical Examination

• Vital Signs: BP 126/78 mmHg, HR 68 bpm, RR 14, SpO2 97% on room air, Temp 36.7°C, BMI 33.8 kg/m², Height 178 cm, Weight 107 kg
• General: Obese, well-appearing male in no acute distress; anxious
• Cardiovascular: Regular rate and rhythm; S1, S2 normal; soft S3 gallop at apex; no murmurs; JVP 8 cm (mildly elevated); right femoral artery access site from PCI: healing well, no hematoma, no bruit
• Pulmonary: Clear to auscultation; no crackles or wheeze
• Abdomen: Obese, soft, non-tender; no hepatomegaly
• Extremities: 1+ bilateral pedal edema; diminished dorsalis pedis and posterior tibial pulses bilaterally (PAD); saphenous veins palpable bilaterally (conduit assessment)
• Neurological: Alert and oriented; no carotid bruits; no focal deficits
• Sternal/chest wall: No prior sternotomy; adequate body habitus for median sternotomy

Workup and Results

Laboratory Studies:

Imaging/Additional Studies:

• Coronary angiography (2 weeks ago): Mid-LAD: patent DES; Proximal LAD: 80% stenosis (diffuse, calcified); Ostial LCx: 90% stenosis; OM1: 85% stenosis; Proximal RCA: 75% stenosis; Distal RCA: 70% stenosis; SYNTAX score: 33 (high — favors CABG)
• Echocardiogram (post-MI, day 5): EF 40% (reduced — anterior wall hypokinesis); LV dilation (LVEDD 58 mm); mild mitral regurgitation (functional); no LV thrombus; no pericardial effusion
• Carotid duplex ultrasound: <50% stenosis bilaterally (no intervention needed)
• Lower extremity ABI: 0.72 right, 0.74 left (moderate PAD — assess conduit implications)
• Pulmonary function tests: FEV1 78% predicted, FVC 80% predicted, FEV1/FVC 0.82 (mildly reduced — acceptable for surgery)
• Bilateral saphenous vein mapping (duplex ultrasound): Right great saphenous vein: suitable caliber (3.5-4.0 mm throughout), no varicosities; Left great saphenous vein: suitable but smaller caliber (2.8-3.2 mm); bilateral radial arteries: Allen test positive bilaterally, right radial artery 2.8 mm diameter (suitable for radial artery graft)
• STS Predicted Risk of Mortality: 2.1% (low-intermediate risk)

Clinical Image

Illustration showing a typical multi-vessel CABG configuration with left internal mammary artery (LIMA) to LAD, radial artery graft to obtuse marginal, and saphenous vein graft to right coronary artery, with on-pump cardiopulmonary bypass circuit depicted. Source: Educational illustration.

Diagnosis

Multivessel Coronary Artery Disease (Three-Vessel + Left Main Equivalent Pattern) — Post-Anterior STEMI with Reduced Ejection Fraction — Indication for Surgical Revascularization (CABG)

Key Diagnostic Criteria:

• High SYNTAX score (33) — randomized trials demonstrate survival benefit of CABG over PCI for SYNTAX >32 (SYNTAX trial, EXCEL trial, NOBLE trial)
• Three-vessel disease with left main equivalent anatomy (proximal LAD + ostial circumflex)
• Diabetes mellitus — FREEDOM trial demonstrated survival benefit of CABG over PCI in diabetic patients with multivessel disease
• Complex, calcified, diffuse lesions not amenable to complete revascularization with PCI
• Reduced EF (40%) post-MI — CABG with LIMA to LAD provides survival benefit in patients with reduced LV function (STICH trial)

Treatment Plan

1. Pre-operative optimization (2-4 week window post-MI):

• Discontinue ticagrelor 5 days pre-surgery (bleeding risk reduction; aspirin continued)
• Optimize glycemic control: target glucose 110-180 mg/dL perioperatively; endocrinology consultation for insulin adjustment
• Continue statin, beta-blocker, ACE inhibitor through morning of surgery
• CPAP compliance optimization; bring CPAP to hospital for post-operative use
• Pre-operative shower with chlorhexidine night before and morning of surgery (SSI prevention)
• Incentive spirometry training pre-operatively
• Type and screen 2 units pRBCs

1. Surgical plan:

• Median sternotomy approach
• Cardiopulmonary bypass with aortic cannulation and bicaval venous cannulation
• Moderate systemic hypothermia (32°C)
• Cardioplegic arrest with antegrade and retrograde blood cardioplegia
• Graft configuration (total arterial preferred strategy):
• LIMA (left internal mammary artery) → LAD (gold standard, >95% 10-year patency)
• Right radial artery → OM1 (second arterial conduit — superior long-term patency vs. SVG in patients <70)
• SVG (right great saphenous vein) → RCA (PDA target)
• Inspect mid-LAD stent area; graft distal to stented segment
• Estimated bypass time: 90-120 minutes; cross-clamp time: 60-80 minutes

1. Intra-operative considerations:

• TEE for LV function assessment, valve competence, cannulation site evaluation, de-airing
• Epiaortic ultrasound to identify safe cannulation/cross-clamp site (minimize stroke risk)
• Strict glycemic control (insulin drip targeting 110-180 mg/dL)
• Cell saver for blood conservation

1. Post-operative management:

• ICU: mechanical ventilation (extubation within 4-8 hours if stable — enhanced recovery protocol)
• Hemodynamic targets: MAP 65-80 mmHg, HR <90 bpm, CVP 8-12 mmHg, CI >2.2 L/min/m²
• Chest tubes (mediastinal and pleural) — remove when output <200 mL/12 hr
• Temporary epicardial pacing wires (remove day 3-4)
• DVT prophylaxis: compression devices intra-op, heparin 5000 units SC TID starting 6 hours post-op
• Restart aspirin within 6 hours post-op; ticagrelor NOT resumed (replaced by aspirin for existing LAD stent)
• Sternal precautions: no lifting >5 lbs for 8 weeks; pillow splinting for cough
• CPAP use post-extubation with sternal precautions awareness

1. Discharge and rehabilitation:

• Anticipated hospital stay: 5-7 days
• Phase I cardiac rehabilitation in hospital (ambulation, stair training)
• Phase II outpatient cardiac rehabilitation starting 2-4 weeks post-discharge (12-week program)
• Return to driving: 4-6 weeks; return to full work activities: 8-12 weeks
• Aggressive secondary prevention: statin (target LDL <70), blood pressure control, diabetes management (target HbA1c <7%), smoking cessation maintenance, weight loss, Mediterranean diet
• Follow-up: surgeon at 2 weeks (wound check), cardiologist at 4 weeks, then every 3-6 months first year

Key Learning Points

• CABG provides a survival benefit over PCI in patients with multivessel disease and high SYNTAX scores (>32), left main disease, diabetes with multivessel disease, and reduced LV function — these indications are supported by Level A evidence from multiple randomized trials
• The LIMA-to-LAD graft is the cornerstone of CABG with >95% patency at 10 years; arterial grafts (radial artery, right IMA) provide superior long-term patency compared to saphenous vein grafts and should be maximized in appropriate patients (total arterial revascularization strategy)
• Timing of CABG after STEMI is optimized at 3-7 days post-MI when feasible (allows myocardial recovery and inflammation resolution while preventing recurrent events); urgent CABG (<48 hours) carries higher mortality but may be necessary for specific indications (left main disease, cardiogenic shock, mechanical complications)
• Perioperative glycemic control in diabetic patients undergoing CABG significantly reduces sternal wound infection, mediastinitis, and mortality; continuous insulin infusion targeting 110-180 mg/dL is standard of care
• Enhanced recovery after cardiac surgery (ERACS) protocols including early extubation, early mobilization, multimodal analgesia (avoiding excess opioids), and pre-operative patient education reduce hospital stay, complications, and improve patient satisfaction

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