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C26 Cardiology and Cardiac Surgery
Chronic stable angina is most often due to a fixed stenosis caused by an atheroma
Acute coronary syndromes are the result of plaque rupture
Canadian Cardiovascular Society (CCS) Functional Classification of Angina
• Class I: ordinary physical activity (walking,
climbing stairs) does not cause angina; angina with strenuous, rapid, or prolonged activity
• Class II: slight limitation of ordinary activity: angina brought on at >2 blocks on level or climbing >1 flight of stairs or by emotional stress
• Class III: marked limitation of ordinary activity: angina brought on at <2 blocks on level or climbing <1 flight of stairs
• Class IV: inability to carry out any physical activity without discomfort; angina may be present at rest
Ischemic Heart Disease Toronto Notes 2019 Chronic Stable Angina
Definition
• symptom complex resulting from an imbalance between oxygen supply and demand in the myocardium
Etiology and Pathophysiology
• factorsthatdecreasemyocardialoxygensupply:
■ decreased luminal diameter: atherosclerosis, vasospasm
■ decreased duration of diastole: tachycardia (decreased duration of diastolic coronary perfusion) ■ decreased hemoglobin: anemia
■ decreased SaO2: hypoxemia
■ congenital anomalies
• factors that increase myocardial oxygen demand:
■ increased heart rate: hyperthyroidism
■ increased contractility: hyperthyroidism
■ increased wall stress: myocardial hypertrophy, aortic stenosis
Signs and Symptoms
• typical
1. retrosternal chest pain, tightness or discomfort radiating to left (± right) shoulder/arm/neck/jaw,
associated with diaphoresis, nausea, anxiety
2. predictably precipitated by the “3 Es”: exertion, emotion, eating
3. brief duration, lasting <10-15 min and typically relieved by rest and nitrates
• atypical/probableangina(meets2oftheabove)
• non-cardiacchestpain(meets<1oftheabove)
• Levine’ssign:clutchingfistoversternumwhendescribingchestpain
• anginalequivalents:dyspnea,acuteLVfailure,flashpulmonaryedema
Clinical Assessment
• historyincludingdirectedriskfactorassessmentandphysicalexam
• labs:Hb,fastingglucose,fastinglipidprofile
• ECG(atrestandduringepisodeofchestpainifpossible)
• CXR(suspectedheartfailure,valvulardisease,pericardialdisease,aorticdissection/aneurysm,orsigns
or symptoms of pulmonary disease)
• stresstesting(seeStressTesting,C13)orangiography
• echo
• toassesssystolicmurmursuggestiveofaorticstenosis,mitralregurgitation,and/orHCM
• toassessLVfunctioninpatientswithHxofpriorMI,pathologicalQwaves,signsorsymptomsofCHF
Differential Diagnosis
• seeDifferentialDiagnosisofCommonPresentations,C4
Treatment of Chronic Stable Angina
1. General Measures
■ goals: to reduce myocardial oxygen demand and/or increase oxygen supply
■ lifestyle modification (diet, exercise)
■ treatment of risk factors: statins (see Endocrinology, E5, Family Medicine, FM10 for target lipid
guidelines), antihypertensives, etc
■ pharmacological therapy to stabilize the coronary plaque to prevent rupture and thrombosis
2. Antiplatelet Therapy (first-line therapy)
■ ASA
■ clopidogrel when ASA absolutely contraindicated
3. β-blockers (first-line therapy – improve survival in patients with hypertension)
■ increase coronary perfusion and decrease demand (HR, contractility) and BP (afterload)
■ cardioselective agents preferred (e.g. metoprolol, atenolol) to avoid peripheral effects (inhibition of
vasodilation and bronchodilation via β2 receptors)
■ avoid intrinsic sympathomimetics (e.g. acebutolol) which increase demand
4. Nitrates (symptomatic control, no clear impact on survival)
■ decrease preload (venous dilatation) and afterload (arteriolar dilatation), and increase coronary perfusion
■ maintain daily nitrate-free intervals to prevent tolerance (tachyphylaxis)
5. Calcium Channel Blockers (CCBs, second-line or combination)
■ increase coronary perfusion and decrease demand (HR, contractility) and BP (afterload)
■ caution: verapamil/diltiazem combined with β-blockers may cause symptomatic sinus bradycardia
or AV block