3: Coronary Artery Disease

Ischemic heart disease (CAD)

Mismatch between myocardial O2 supply and demand

MCC of ischemic heart disease (CAD)

Atherosclerotic disease of coronary artery resulting in regional reduction in blood flow

Degrees of atherosclerosis

50% reduction of vessel diameter → decreased ability of artery to adapt to demand (symptomatic on exertion)

80% reduction of vessel diameter → decreased flow at rest

Atherosclerosis

- Progressive

- Fat deposits in sub-intimal part of arteries

- Lumen narrows

- Loss of ability to dilate

Atherosclerotic plaque

- Fat, smooth muscle cells, fibroblasts, intracellular matrix

- STABLE, NOT thrombogenic

Rupture of atherosclerotic plaque

- Acute coronary syndrome

- Clot forms → blockage of distal blood flow → acute myocardial ischemia

Risk factors for CAD

- Diabetes

- Dyslipidema (high LDL, low HDL)

- Chronic inflammation

Assessment of chronic inflammation for CAD

High-sensitivity CRP as inflammatory marker

Family history risk for CAD

1st degree relative with MI/CVA <55 (males) or <65 (F)

Cardioprotective component

Estrogen → Post-menopausal females have increased risk of CAD

Prevention of CAD

- Control blood sugar

- Smoking cessation (risk declines 50% after 1 year)

- Statins for hyperlipidemia

Clinical presentations of CAD

- Chronic stable angina

- Acute coronary syndrome (unstable angina, NSTEMI, STEMI)

Chronic stable angina

- Episodic due to atherosclerotic plaque causing transient myocardial ischemia

- MC on exertion

- Relieved within 5 mins OR with sublingual nitroglycerin

General presentation of chronic stable angina

All symptoms intermittent, brought on by exertion, relieved with rest

Typical symptoms of chronic stable angina

- Chest discomfort localized in central/substernal

- Squeezing, crescendo-decrescendo, heaviness, pressure

- Radiation to shoulder/arm, jaw, neck, back

Which population are more prone to atypical symptoms/presentation of chronic stable angina?

Women, diabetics, elderly

Atypical symptoms of chronic stable angina

- Epigastric, back, arm, neck/jaw

- Instead of chest pain/pressure → dyspnea, N/V, general fatigue, lightheaded/syncope

HPI w/ presentation of stable angina

- Characteristics of pain, radiation

- Provoking/palliating factors

- Exercise tolerance, change from baseline

PE w/ presentation of stable angina

- Normal between episodes

- Eval for signs of vascular disease

- Palpate chest for reproducible pain (MSK, NOT cardiac)

Signs of vascular disease

BP - both arms/legs

Eye - xanthomas, AV nicking

Neck - carotid bruit

Heart - displaced PMI

Pleuritic pain

Sharp, focal, associated with deep breath

DDx of GI

- Reflux/trapped gas in colon

- Timing to meals, location, quality of pain

Initial testing for stable angina

EKG - normal at rest; observe for old MI, LVH, bundle branch block

Urine - protein, glucose, microalbumin

Blood - lipid, A1C, creatinine (BMP), CBC

CXR

When would CXR be indicated for stable angina workup?

Dyspnea with exertion

Confirmatory test for stable angina

- Stress testing to compare heart at rest and under stress

- Analyze for decreased perfusion (coronary artery stenosis marker)

Exercise stress test

- 12 lead EKG before, during, after

- Monitor VS, symptoms

- Incremental increase in workload

** Medical profession must be present with resuscitation equipment

Documentation of exercise stress test

- Duration and workload achieved

- Onset of symptoms / EKG changes and severity/location

- Time for recovery of EKG changes

Results of exercise stress test

(+) → Chest discomfort, SOB, ST segment depression >2 mm, sBP drop >10 mmHg, development of ventricular arrhythmia

(-) → 85% of maximal predicted HR

**Discontinue once positive

Contraindications for exercise stress test

- Rest angina within 48 hrs

- Unstable baseline rhythm

- Acute myocarditis

Alternative to exercise stress test

Pharmacological stress test

Pharmacological stress test

- Vasodilator (adenosine/dipyridamole) to increase flow to non-diseased coronary arteries → decrease flow to diseased

- Diseased segments CANNOT dilate

- Used with myocardial perfusion imaging

Cardiac perfusion imaging

- Nuclear med/PET scan with nuclear marker injected during stress test

- Images during stress, then at rest

Common types of nuclear markers for cardiac perfusion imaging

IV thallium or technetium sestamibi

Results of stress and rest scans in cardiac perfusion imaging

Reversible perfusion changes → ischemia

Irreversible perfusion changes → infarction

Stress echocardiogram

- Used with exercise stress test or dobutamine

- Observe for dysfunction and regional wall abnormalities of LV

Results of stress echocardiogram

Abnormal during stress, normal at rest → suggests CAD

Coronary Ca score

- CT to evaluate Ca in coronary arteries

- High score → higher risk for future coronary event

Evaluation of pt with known or suspected CAD

- Uncertain of CAD dx

- Assess functional capacity

- Assess adequacy of treatment

- Abnormal calcium score on EBCT

Gold standard for assessment of coronary vasculature

Cardiac catheterization/coronary angiography

Indications for cardiac catheterization

- Eval severity of CAD in symptomatic pt, determine if intervention required

- Preop for valve placement (tests tolerance, can treat CAD simultaneously)

Preparation for cardiac catheterization

- 6 hr fasting for conscious sedation

- Suspect/known CAD → aspirin 325 mg

- Suspected intervention → additional antiplatelet agent (loading dose of clopidogrel)

- On anticoagulation: Warfarin < 1.7 / Off NOAC x 24-48 hours

Cardiac catheterization procedure

- Femoral or radial artery approach

- Catheter from aorta into LV to measure pressures and CO, assess for valve dysfunction

- Coronary angiography to eval stenosis/narrowing of vessels

Coronary angiography procedure + results

- L and R coronary injected with contrast observed with fluoroscopy

- Stenosis >50% is significant

- PCI/stenting as needed

Post-cardiac catheterization

**Monitor for bleeding

- Vascular sheath removal

- Direct compression

- Bed rest

- Fluids to rid of dye

- High risk / all PCI → overnight observation

Risks of cardiac catheterization

- Extremely low risk for MI, death, stroke

- Cardiac arryhthmia

- Access site bleeding: hematoma or pseudoaneurysm (MC)

Hematoma

Soft/firm, NON-pulsatile, NO bruit

Pseudoaneurysm

- Weak spot in artery, risk of rupture

- PULSATILE + BRUIT (unlike hematoma)

Relative contraindications for cardiac catheterization

- Advanced CKD (dye constricts and damages kidneys)

- GI bleed/aspirin sensitivity

Management of CAD

- Lifestyle modification (always)

- HTN w/ BB, nitrates

- Maintain diabetes

Pharmaceuticals for CAD

- BB for regimens of ALL CAD patients (decrease mortality with hx of MI)

Antiplatelet

- Enteric coated aspirin 81-162 mg daily

- ASA inhibits platelet activation

Pharmacological management of patients with stents placed

Dual anti-platelet therapy

Statin therapy

High intensity statin to keep LDL <70

Beta blockers

- Block beta-adrenergic activity

- Reduce HR, contractility, arterial pressure (decreased workload of heart)

- Anti-hypertensive

- Reduce myocardial O2 demand → reduces angina on exertion

Avoid beta blockers in patients with....

- Prinzmetal angina

- AV conduction disease

- Raynaud's

Adverse rxn of beta blockers

Enhanced action of hypoglycemic meds (risk of blood sugar dropping too low)

Beta blockers and bronchospasm

Metoprolol and atenolol preferred

Calcium channel blockers

- Coronary vasodilators

- Use when BB contraindicated, poorly tolerated, ineffective

- Amlodipine common addition to BB

Preferred med for prinzmetal angina

Calcium channel blockers

Medications for avoid in AV conduction disease and bradycardia

Verapamil and diltiazem (Ca channel blockers)

Function of nitrates

- Arterial and venous dilation to reduce EDP and volume, myocardial tension and O2 requirements

- Increase flow through collateral vessels

Short-acting nitroglycerin

- RAPID onset

- Use during angina episode OR prophylactic before activity known to cause angina

Long-acting nitrates

- Prevention of angina

- Isosorbide (oral), nitroglycerin patch (remove for 12 hr to prevent tolerance)

Cautions with nitrates

- Can cause orthostatic hypotension, hypotension

- DO NOT use with hypotensive or hypertrophic obstructed cardiomyopathy

Other meds to reduce MI risk

- GLP1 receptor agonists

- Ranazoline (Ranexa)

What medication is used for symptoms of chronic stable angina that is not responsive to standard therapy? What does it do?

Ranazoline (Ranexa) - acts on Na/Ca exchange in myocytes

Patients with CAD should avoid....

NSAIDs!

- If necessary, use with daily aspirin with lowest dose possible

Considerations for coronary revascularization for CAD

- Unstable angina

- Diabetes

- Impaired LV

Percutaneous coronary intervention (PCI)

Guidewire through stenosed vessels, angioplasty balloon inflated to dilate lumen, stent placed to hold vessel open

Management post-PCI

Require dual antiplatelet therapy for at least a year with strict adherence

Coronary artery bypass graft (CABG)

- New vessels byspass diseased

- Internal mammary or radial artery is anastomosed to diseased coronary artery, distal to obstruction

Conditions when CABG preferred over PCI

- L main artery disease

- 3 vessel disease in diabetics/cardiomyopathy

Acute coronary sydrome

Acute rupture of coronary artery atherosclerotic plaque

Presentations of acute coronary syndrome

1. Unstable angina

2. NSTEMI

3. STEMI

**ALLL have chest pain @ rest

Characteristics of unstable angina

- (-) cardiac enzymes

- NO EKG changes

Characteristics of NSTEMI

- (+) cardiac enzymes

- No ST elevations

Characteristics of STEMI

- (+) cardiac enzymes

- ST elevations

Keep in mind when dx ACS...

Chronic stable angina & acute coronary syndrome, symptoms generally same

Symptoms of ACS

- Severe chest pressure

- Radiate to arm(s)

- Diaphoresis, nausea

- NO improvement with rest/nitrates

- >5 mins

Initial workup of suspected MI

- VS

- EKG

- IV access

- Focused hx & PE

- Cardiac enzymes, CBC, BMP, coag

- CXR

History components for suspected MI

PMH — Diabetic, kidney disease

Meds — Anticoagulants, nitrates

Fam — CAD/sudden cardiac death

Social — Substance use (esp cocaine)

PE signs of heart failure/cardiogenic shock

- AMS

- Cool/clammy/diaphoretic skin

- Decreased peripheral pulses

- Low BP

Significant findings for NSTEMI

Two anatomic leads with either:

- Horizontal OR downscoping ST depression ≥ 0.5mm OR

- T wave inversion

Significant findings for STEMI

Two anatomic leads with either:

- New ST-elevation at J-joint ≥ 1-2 mm

- New left bundle branch block

Assessing cardiac enzymes in ACS

CPK (detectable in blood 4-6 hours)

Troponin** (detectable in blood 3-8 hours)

Check @ arrival + 4-6 hours later

Diagnostic: Rise in levels w/ at least 1 measurement >99th% of upper reference limit & evidence of ischemia

** High-sensitivity troponin detection in 1-2 hours (preferred in ED)

Cardiac enzymes in STEMI

Positive

**Can be within normal limits at diagnosis

Cardiac enzymes in NSTEMI

Positive

- Initial level & rate of change determines risk for MI

Management of ACS (all types)

- Aspirin 162-325 mg PO chewed (anti platelet)

- Nitroglycerin (vasodilation, unless BP <100)

- Heparin IV or lovenox SQ (anti-coag)

- BB (unless signs of heart failure)

Management of ACS before cath lab

Load with P2Y12 inhibitor

Reperfusion therapy for STEMI

Cath lab within 90 minutes of arrival

Reperfusion therapy for NSTEMI

Cath lab soon; STAT if sx recur after giving medications

Reperfusion therapy for unstable angina

Monitor potential stress test

Cath lab if sx/EKG changes

Fibrinolysis (thrombolysis)

- IV meds to dissolve clots

- Many contraindications w/ risk of internal bleeding

Using PCI vs. fibrinolysis (thrombolysis)

PCI — preferred

Thrombolysis — if no cath lab within 2 hours

MC complications of myocardial infarction

- Acute LV failure

- Lethal ventricular arrhythmia

Post-infarction management

Tele monitoring until stable for discharge

Post-infarcation secondary prevention

Stent → BB, dual antiplatelet therapy (w/ compliance for 12+ months)

High potency stain (lowest LDL possible)

Prinzmetal angina (AKA variant angina)

(Associations, risk factors, symptoms, presentation)

- Abrupt, transient vasospasm of coronary artery

- Symptomatic at night (rest)

- Younger people, Raynaud's, migraines

- NO symptoms → NO EKG changes

Diagnosis of prinzmetal angina

- ST elevation only during chest discomfort

- Elevated cardio enzymes

Gold standard:

Cardiac cath → ACh to induce vasospasm

Treatment of prinzmetal angina

- Smoke cessation

- CCB (diltiazem, nifedipine)

- Nitrates

- Statins (to prevent atherosclerosis)