Pocket Medicine

CARDIOLOGY

CARDIOMYOPATHIES

Diseases with mechanical and/or electrical dysfunction of the myocardium

DILATED CARDIOMYOPATHY (DCMP)

Definition and epidemiology (Circ 2006;113:1807)

•  Ventricular dilatation and ↓ contractility ± ↓ wall thickness

•  Incidence: 5–8/100,000/yr; prevalence: 1/2500. Most common reason for heart transplant.

Etiologies (NEJM 2000;342:1077; Circ Res 2012;111:131)

•  Ischemia/infarct: systolic dysfxn & dilation due to poor remodeling post-MI

•  Valvular disease: systolic dysfxn due to chronic volume overload in MR & AI

•  Familial (~25%): mutations in cytoskeletal, nuclear and filament proteins (NEJM 1992;362:77)

•  Idiopathic (~25%): ? undiagnosed infectious, alcoholic or genetic cause

•  Infectious myocarditis (10–15%, autoimmune response; Lancet 2012;379:738)

Viruses (parvoB19 & HHV6 > coxsackie, adeno, echo, CMV, HCV): from subacute (dilated LV, mild–mod dysfxn) to fulminant (nondil., thick, edematous LV, sev dysfxn)

Bacterial, fungal, rickettsial, TB, Lyme (mild myocarditis, often with AVB)

HIV: ~8% of asx HIV ; due to HIV, other virus or antiretrovirals; HIV also associated w/ premature CAD (Circ 2008;118:e36; Heart 2009;95:1193)

Chagas: apical aneurysm ± thrombus, RBBB, megaesophagus/colon (NEJM 1993;329:639)

•  Toxic: alcohol (5%) typ. 7–8 drinks/d × >5 y, but variable; cocaine; XRT (usu RCMP);

anthracyclines (risk ↑ >550 mg/m2, may manifest late), cyclophosphamide, trastuzumab

•  Infiltrative (5%): often mix of DCMP + RCMP (qv) with thickened wall

amyloidosis, sarcoidosis, hemochromatosis, tumor

•  Autoimmunecollagen vasc. dis. (3%): PM, SLE, scleroderma, PAN, RA, Wegener’s;

peripartum (last month → 5 mo postpartum; JACC 2011;58:659): ~1:3000 preg. ↑ risk w/ multiparity, ↑ age, Afr Am; stnd HF Rx except if preg then select drugs based on safety; ? bromocriptine to ↓ prolactin; ~½ normalize EF; even if nl EF ~30% recur w/ next preg

Idiopathic giant cell myocarditis (GCM): avg age 42 y, fulminant, VT (NEJM 1997;336:1860)

Eosinophilic (variable peripheral eos): hypersensitivity (mild HF) or acute necrotizing eosinophilic myocarditis (ANEM; STE, effusion, severe HF)

•  Stress-induced (Takotsubo = apical ballooning): mimics MI (pain, ± STE & ↑ Tn; deep TWI & ↑ QT); mid/apex dyskinesis; ? Rx w/ bB, ACEI; usu. improves over wks (JAMA 2011;306:277)

•  Tachycardia: likelihood ∝ rate/duration; often resolves w/ rate cntl (Circ 2005;112:1092)

•  Arrhythmogenic right ventricular cardiomyopathy (ARVC): fibrofatty replacement of RV → dilation (dx w/ MRI); ECG: ± RBBB, TWI V1–V3, e wave; risk VT (Lancet 2009;373:1289)

•  Metab/other: hypothyroid., acromegaly, pheo, OSA, thiamine, selenium or carnitine defic

Clinical manifestations

•  Heart failure: both congestive & poor forward flow sx; signs of L- & R-sided HF

diffuselaterally displaced PMIS3, ± MR or TR (annular dilat., displaced pap. muscle)

•  Embolic events (~10%), supraventricular/ventricular arrhythmias, & palpitations

•  Chest pain can be seen w/ some etiologies (eg, myocarditis)

Diagnostic studies and workup

•  CXR: moderate to marked cardiomegaly, ± pulmonary edema & pleural effusions

•  ECG: may see PRWP, Q waves or BBB; low-voltage; AF (20%); may be normal

•  Echocardiogram: LV dilatation, ↓ EF, regional or global LV HK ± RV HK, ± mural thrombi

•  Cardiac MRI: up to 76% Se, 96% Sp for myocarditis or infiltrative dis. ( JACC 2005;45:1815); extent of midwall fibrosis correlated w/ mortality in NICMP ( JAMA 2013;309:896)

•  Laboratory evaluation: TFTs, iron studies, HIV, SPEP, ANA; others per clinical suspicion; viral serologies not recommended ( JACC 2012;59:779)

•  Family hx (20–35% w/ familial dis.), genetic counseling ± genetic testing ( JAMA 2009;302:2471)

•  Stress test: useful to r/o ischemia (low false  rate), high false  rate, even w/ imaging

•  Coronary angiography to r/o CAD if risk factors, h/o angina, Qw MI on ECG, equivocal ETT; consider CT angiography (JACC 2007;49:2044)

•  ? Endomyocardial biopsy (JACC 2007;50:1914): yield 10% (of these, 75% myocarditis, 25% systemic disease); 40% false  rate (patchy dis.) & false  (necrosis → inflammation)no proven Rx for myocarditis; ∴ biopsy if: acute & hemodyn compromise (r/o GCM, ANEM); arrhythmia or RCMP features (r/o infiltrative); or suspect toxic, allergic, tumor

Treatment (see “Heart Failure” for standard HF Rx)

•  Implantation of devices may be tempered by possibility of reversibility of CMP

•  Immunosuppression: for giant cell myocarditis (prednisone + AZA), collagen vascular disease, peripartum (? IVIg), & eosinophilic; no proven benefit for viral myocarditis

•  Prognosis differs by etiology (NEJM 2000;342:1077): postpartum (best), ischemic/GCM (worst)

HYPERTROPHIC CARDIOMYOPATHY (HCMP)

Definition and epidemiology

•  LV (usually ≥15 mm) and/or RV hypertrophy disproportionate to hemodynamic load

•  Prevalence: 1/500; 50% sporadic, 50% familial, most asymptomatic

•  Ddx: LVH 2° to HTN, AS, elite athletes (wall usually <13 mm & symmetric and nl/↑ rates of tissue Doppler diastolic relaxation; Circ 2011;123:2723), Fabry dis. (↑ Cr, skin findings)

Pathology

•  Autosomal dominant mutations in cardiac sarcomere genes (eg, b-myosin heavy chain)

•  Myocardial fiber disarray with hypertrophy, which creates arrhythmogenic substrate

•  Morphologic hypertrophy variants: asymmetric septal; concentric; midcavity; apical

Pathophysiology

•  Subaortic outflow obstruction: narrowed tract 2° hypertrophied septum + systolic anterior motion (SAM) of ant. MV leaflet (may be fixed, variable or nonexistent) and papillary muscle displacement. Gradient (∇) worse w/ ↑ contractility (digoxin, b- agonists, exercise, PVCs), ↓ preload or ↓ afterload.

•  Mitral regurgitation: due to SAM (mid-to-late, post.-directed regurg. jet) and/or abnl

mitral leaflets and papillary muscles (pansystolic, ant.-directed regurg. jet)

•  Diastolic dysfunction: ↑ chamber stiffness + impaired relaxation

•  Ischemia: small vessel dis., perforating artery compression (bridging), ↓ coronary perfusion

•  Syncope: Δs in load-dependent CO, arrhythmias

Clinical manifestations (70% are asymptomatic at dx)

•  Dyspnea (90%): due to ↑ LVEDP, MR, and diastolic dysfunction

•  Angina (25%) even w/o epicardial CAD; microvasc. dysfxn (NEJM 2003;349:1027)

•  Arrhythmias (AF in 20–25%; VT/VF) → palpitations, syncope, sudden cardiac death

Physical exam

•  Sustained PMI, S2 paradoxically split if severe outflow obstruction,  S4 (occ. palpable)

•  Systolic murmur: crescendo-decrescendo; LLSB; ↑ w/ Valsalva & standing (↓ preload)

•  ± mid-to-late or holosystolic murmur of MR at apex

•  Bifid carotid pulse (brisk rise, decline, then 2nd rise); JVP w/ prominent a wave

•  Contrast to AS, which has murmur that ↓ w/ Valsalva and ↓ carotid pulses

Diagnostic studies

•  CXR: cardiomegaly (LV and LA)

•  ECG: LVH, anterolateral and inferior pseudo-Qw, ± apical giant TWI (apical variant)

•  Echo: no absolute cutoffs for degree of LVH but septum/post. wall ≥1.3 suggestive,

as is septum >15 mm; other findings include dynamic outflow obstruction, SAM, MR

•  MRI: hypertrophy + patchy delayed enhancement (useful for dx & prog) ( JACC CV Imag 2012;2:370)

•  Cardiac cath: subaortic pressure ∇; Brockenbrough sign = ↓ pulse pressure post-PVC (in contrast to AS, in which pulse pressure ↑ post-PVC)

•  ? Genotyping for family screening, but pathogenic mutation ID’d in <½ (Circ 2011;124:2761)

Treatment (Circ 2011;124:e783 & 2012;125:1432; Lancet 2013;381:242)

•  Heart failure

 inotropes/chronotropes: b-blockers, CCB (verapamil), disopyramide

Careful use of diuretics, as may further ↓ preload. Vasodilators only if systolic dysfxn. Avoid digoxin.

If sx refractory to drug Rx + obstructive physiology (∇ >50 mmHg):

(a) Surgical myectomy: long-term ↓ symptoms in 90% (Circ 2005;112:482)

(b) Alcohol septal ablation (Circ CV Interv 2011;4;256; JACC 2011;58:2322): gradient ↓ by ~80%, only 5–20% remain w/ NYHA III–IV sx; 14% require repeat ablation or myectomy. Good alternative for older Pts, multiple comorbidities. Complic: transient (& occ. delayed) 3° AVB w/ 10–20% req. PPM; VT due to scar formation.

No clear benefit of dual-chamber pacing ( JACC 1997;29:435; Circ 1999;99:2927)

If refractory to drug therapy and there is nonobstructive pathophysiology: transplant

•  Acute HF: can be precip. by dehydration or tachycardia; Rx w/ fluids, bB, phenylephrine

•  AF: rate control with bB, maintain SR with disopyramide, amiodarone

•  SCD: ICD ( JACC 2003;42:1687). Risk factors: h/o VT/VF,  FHx SCD, unexplained syncope, NSVT, ↓ SBP or rel HoTN (↑ SBP <20 mmHg) w/ exercise, LV wall ≥30 mm, extensive MRI delayed enhancement. EPS not useful. Risk 4%/y if high-risk (JAMA 2007;298:405).

•  Counsel to avoid dehydration, extreme exertion

•  Endocarditis prophylaxis not recommended (Circ 2007;16:1736)

•  First-degree relatives: periodic screening w/ echo, ECG (as timing of HCMP onset variable). Genetic testing if known mutation.

RESTRICTIVE CARDIOMYOPATHY (RCMP)

Definition (Circ 2006;113:1807)

•  Impaired ventricular filling with ↓ complicance in nonhypertrophied, nondilated ventricles; normal or ↓ diastolic volumes, normal or near-normal EF; must r/o pericardial disease

Etiology ( JACC 2010;55:1769)

•  Myocardial processes

Autoimmune (scleroderma, polymyositis-dermatomyositis)

Infiltrative diseases (see primary entries for extracardiac manifestations, Dx, Rx)

Amyloidosis (CIrc 2011;124:1079): age at presentation ~60 y; : = 3:2 AL (MM, light-chain, MGUS, WM); familial (transthyretin, TTR); AA/senile (TTR, ANP) ECG: ↓ QRS amplitude (50%), pseudoinfarction pattern (Qw), AVB (10–20%),  hemiblock (20%), BBB (5–20%)

Echo: biventricular wall thickening (yet w/ low voltage on ECG), granular sparkling texture (30%), biatrial enlargement (40%), thickened atrial septum, valve thickening (65%), diastolic dysfxn, small effusions

Normal voltage & normal septal thickness has NPV ~90%

MRI: distinct late gadolinium enhancement pattern ( JACC 2008;51:1022)

Sarcoidosis: age at present. ~30 y; more common in blacks, N. Europeans, women

5% of those w/ sarcoid have overt cardiac involvement; cardiac w/o systemic in 10%

ECG: AVB (75%), RBBB (20–60%), VT; PET: ↑ FDG uptake in affected area

Echo: regional WMA (particularly basal septum) with thinning or mild hypertrophy

Nuclear imaging: gallium uptake in areas of sestaMIBI perfusion defects; cardiac MR

Hemochromatosis: in middle-aged men (esp. N. European); 15% p/w cardiac sx

Storage diseases: Gaucher’s, Fabry, Hurler’s, glycogen storage diseases

Diabetes mellitus

•  Endomyocardial processes

Chronic eosinophilic: Löffler’s endocarditis (temperate climates; ↑ eos; mural thrombi that embolize); endomyocardial fibrosis (tropical climates; var. eos; mural thrombi)

Toxins: radiation (also p/w constrictive pericarditis, valvular dis, ostial CAD), anthracyclines

Serotonin: carcinoid, serotonin agonists, ergot alkaloids

Metastatic cancer

Pathology & pathophysiology

•  Path: normal or ↑ wall thickness ± infiltration or abnormal deposition

•  ↓ myocardial compliance → nl EDV but ↑ EDP → ↑ systemic & pulm. venous pressures

•  ↓ ventricular cavity size → ↓ SV and ↓ CO

Clinical manifestations (Circ 2000;101:2490)

•  Right-sided > left-sided heart failure with peripheral edema > pulmonary edema

•  Diuretic “refractoriness”

•  Thromboembolic events

•  Poorly tolerated tachyarrhythmias; VT → syncope/sudden cardiac death

Physical exam

•  ↑ JVP, ± Kussmaul’s sign ( JVP ↑ w/ inspiration, classically seen in constrictive pericarditis)

•  Cardiac: ± S3 and S4, ± murmurs of MR and TR

•  Congestive hepatomegaly, ± ascites and jaundice, peripheral edema

Diagnostic studies

•  CXR: normal ventricular chamber size, enlarged atria, ± pulmonary congestion

•  ECG: low voltage, pseudoinfarction pattern (Qw), ± arrhythmias

•  Echo: symmetric wall thickening, biatrial enlarge., ± mural thrombi, ± cavity oblit. w/ diast dysfxn: ↑ early diast (E) and ↓ late atrial (A) filling, ↑ E/A ratio, ↓ decel. time

•  Cardiac MRI/PET: may reveal inflammation or evidence of infiltration (but nonspecific)

•  Cardiac catheterization

Atria: M’s or W’s (prominent x and y descents)

Ventricles: dip & plateau (rapid ↓ pressure at onset of diastole, rapid ↑ to early plateau)

Concordance of LV and RV pressure peaks during respiratory cycle (vs. discordance in constrictive pericarditis; Circ 1996;93:2007)

•  Endomyocardial biopsy if suspect infiltrative process

•  Restrictive cardiomyopathy vs. constrictive pericarditis: see “Pericardial Disease”

Treatment (in addition to Rx’ing underlying disease)

•  Gentle diuresis. May not tolerate CCB or other vasodilators.

•  Control HR (but can ↓ CO); maintain SR (helps filling). Digoxin ↑ arrhythmias in amyloid.

•  Anticoagulation (particularly with AF or low CO)

•  Transplantation for refractory cases