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C40 Cardiology and Cardiac Surgery
Myocardial Disease
Toronto Notes 2019
Major Risks Factors for DCM
Alcohol, cocaine, family history
Abnormal Labs in DCM
• High BNP
• High Cr
• High LFTs
• Lowbicarbonate • LowNa+
Dilated Cardiomyopathy
Definition
• unexplaineddilationandimpairedsystolicfunctionofoneorbothventricles
Etiology
• idiopathic(presumedviraloridiopathic)~50%ofDCM • alcohol
• familial/genetic
• uncontrolledtachycardia(e.g.persistentrapidAFib)
• collagenvasculardisease:SLE,polyarteritisnodosa,dermatomyositis,progressivesystemicsclerosis
• infectious:viral(coxsackieB,HIV),Chagasdisease,Lymedisease,Rickettsialdiseases,acuterheumatic
fever, toxoplasmosis
• neuromusculardisease:Duchennemusculardystrophy,myotonicdystrophy,Friedreich’sataxia
• metabolic:uremia,nutritionaldeficiency(thiamine,selenium,carnitine)
• endocrine: hyper/hypothyroidism, DM, pheochromocytoma
• peripartum
• toxic:cocaine,heroin,organicsolvents
• drugs:chemotherapies(doxorubicin,cyclophosphamide),anti-retrovirals,chloroquine,clozapine,TCA • radiation
Signs and Symptoms
• maypresentas: ■ CHF
■ systemic or pulmonary emboli
■ arrhythmias
■ sudden death (major cause of mortality due to fatal arrhythmia)
Investigations
• bloodwork:CBC,electrolytes,Cr,bicarbonate,BNP,CK,troponin,LFTs,TSH,TIBC
• ECG:variableST-Twaveabnormalities,poorRwaveprogression,conductiondefects(e.g.BBB),
arrhythmias (non-sustained VT)
• CXR:globalcardiomegaly(globularheart),signsofCHF,pleuraleffusion
• echo:chamberenlargement,globalhypokinesis,depressedLVEF,MRandTR,muralthrombi
• endomyocardialbiopsy:notroutine,usedtoruleoutatreatablecause
• coronaryangiography:inselectedpatientstoexcludeischemicheartdisease
Management
• treatunderlyingdisease:e.g.abstinencefromalcohol
• treatCHF:seeHeartFailure,C34
• thromboembolismprophylaxis:anticoagulationwithwarfarin
■ indicated for: AFib, history of thromboembolism or documented thrombus
• treatsymptomaticorseriousarrhythmias
• immunizeagainstinfluenzaandS.pneumoniae
• considersurgicaloptions(e.g.LVAD,transplant,volumereductionsurgery)inappropriatecandidates
with severe, drug refractory disease
• considerICDamongpatientswithaLVEF<30%
Prognosis
• dependsonetiology
• betterwithreversibleunderlyingcause,worstwithinfiltrativediseases,HIV,drug-induced
• causeofdeathusuallyCHF(duetopumpfailure)orsuddendeath2°toventriculararrhythmias • systemicemboliaresignificantsourceofmorbidity
• 20%mortalityin1styr,10%peryearafter
Hypertrophic Cardiomyopathy
• see2011ACCF/AHAGuidelinefortheDiagnosisandTreatmentofHypertrophicCardiomyopathyfordetails
Definition
• definedasunexplainedventricularhypertrophy
• variouspatternsofHCMareclassified,butmostcausesinvolvepatternofseptalhypertrophy
Etiology and Pathophysiology
• histopathologicfeaturesincludemyocytedisarray,myocytehypertrophy,andinterstitialfibrosis
• causeisfelttobeageneticdefectinvolvingoneofthecardiacsarcomericproteins(>400mutations
associated with autosomal dominant inheritance, incomplete penetrance)
• prevalenceof1/500-1/1,000ingeneralpopulation
• generallypresentsinearlyadulthood
Hemodynamic Classification
• hypertrophicobstructivecardiomyopathy(HOCM):dynamicLVoutflowtract(LVOT)obstruction, either at rest or with provocation, defined as LVOT gradient of at least 30 mmHg
■ dynamic i.e. obstruction (and the murmur) is reduced with maneuvers that increase preload, and augmented with maneuvers that reduce preload