Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (11 page)

• Etiologies (impaired relaxation and/or ↑ passive stiffness): ischemia, prior MI, LVH, HCMP, infiltrative CMP, RCMP, aging, hypothyroidism • Precipitants of pulmonary edema:
volume overload
(poor compliance of LV → sensitive to even modest ↑ in volume);
ischemia
(↓ relaxation);
tachycardia
(↓ filling time in diastole),
AF
(loss of atrial boost to LV filling);
HTN
(↓ afterload → ↓ stroke volume) • Dx w/ clinical s/s of HF w/ preserved systolic fxn. Dx supported by evidence of diast dysfxn:

(1) echo: abnl MV inflow (E/A reversal and Δs in E wave deceleration time) & ↓ myocardial relax. (↑ isovol relax. time & ↓ early diastole tissue Doppler vel)

(2) exercise-induced ↑ PCWP (± ↓ response chronotropic & vasodilator reserve)

• Treatment: diuresis for vol overload, BP control, prevention of tachycardia and ischemia;

no benefit to: ACEI/ARB (
NEJM
2008;359:2456), PDE5 inhib ( 
JAMA
2013;309:1268)

spironolactone improves LV fxn, but not sx ( 
JAMA
2013;309:781)

combined ARB/neprilysin (neutral endopeptidase) inhib under study (
Lancet
2012;380:1387)

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/m
²
, may manifest late), cyclophosphamide, trastuzumab

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

amyloidosis, sarcoidosis, hemochromatosis, tumor

•
Autoimmune
:
collagen 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 V
₁
–V
₃
, 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

diffuse
,
laterally displaced PMI
,
S3
, ± 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