Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (8 page)

PREDISCHARGE CHECKLIST AND LONG-TERM POST-ACS MANAGEMENT

Risk stratification

• Stress test if anatomy undefined; consider stress if signif residual CAD post-PCI of culprit • Assess LVEF prior to d/c; EF ↑ ~6% in STEMI over 6 mo ( 
JACC
2007;50:149)
Medications (barring contraindications)

•
Aspirin
: 81 mg daily •
P2Y12 inhib
(eg, clopi, prasugrel or ticagrelor): ≥12 mo if stent (min 1 mo after BMS); some PPIs interfere w/ biotransformation of clopi and ∴ plt inhibition, but no convincing impact on clinical outcomes (
Lancet
2009;374:989;
NEJM
2010;363:1909); use w/PPIs if h/o GIB or multiple GIB risk factors ( 
JACC
2010;56:2051) •
β-blocker
: 23% ↓ mortality after MI •
Statin
: high-intensity lipid-lowering (eg, atorvastatin 80 mg,
NEJM
2004;350:1495) •
ACEI
: lifelong if HF, ↓ EF, HTN, DM; 4–6 wk or at least until hosp. d/c in all STEMI

? long-term benefit in CAD w/o HF (
NEJM
2000;342:145 & 2004;351:2058;
Lancet
2003;362:782)

• Aldosterone antag: 15% ↓ death if EF <40% & either DM or s/s of HF (
NEJM
2003;348:1309) • Nitrates: standing if symptomatic; SL NTG prn for all • Oral anticoagulants: if warfarin needed in addition to ASA/clopi (eg,  AF or LV thrombus), target INR 2–2.5. ? stop ASA if at high bleeding risk on triple Rx (
Lancet
2013;381:1107). Low-dose rivaroxaban (2.5 mg bid) in addition to ASA & clopi → 16% ↓ D/MI/stroke and 32% ↓ all-cause death, but ↑ major bleeding and ICH (
NEJM
2012;366:9).

ICD (
NEJM
2008;359:2245)

• If sust. VT/VF >2 d post-MI not due to reversible ischemia • Indicated in 1° prevention of SCD if post-MI w/ EF ≤30–40% (NYHA II–III) or ≤30–35% (NYHA I); need to wait ≥40 d after MI (
NEJM
2004;351:2481 & 2009;361:1427)
Risk factors and lifestyle modifications (
Circ
2011;124:2458)

• Low chol. (<200 mg/d) & fat (<7% saturated) diet; LDL goal <70 mg/dL; ? Ω;-3 FA • BP <140/90 mmHg; smoking cessation • If diabetic, tailor HbA1c goal based on Pt (avoid TZDs if HF) • Exercise (30–60 min 5–7 ×/wk); cardiac rehab; BMI goal 18.5–24.9 kg/m
²

• Influenza vaccination (
Circ
2006;114:1549); screen for depression

PA CATHETER AND TAILORED THERAPY

Rationale

• Cardiac output (CO) = SV × HR; SV depends on LV end-diastolic volume (LVEDV)
∴ manipulate LVEDV to optimize CO while minimizing pulmonary edema • Balloon at tip of catheter inflated → floats into “wedge” position. Column of blood extends from tip of catheter, through pulmonary circulation, to a point just proximal to LA. Under conditions of no flow, PCWP
LA pressure
LVEDP, which is proportional to LVEDV.

• Situations in which these basic assumptions fail:

(1) Catheter tip not in West lung zone 3 (and ∴ PCWP = alveolar pressure ≠ LA pressure); clues include lack of
a
&
v
waves and if PA diastolic pressure < PCWP

(2) PCWP > LA pressure (eg, mediastinal fibrosis, pulmonary VOD, PV stenosis)

(3) Mean LA pressure > LVEDP (eg, MR, MS)

(4) Δ LVEDP-LVEDV relationship (ie, abnl compliance, ∴ “nl” LVEDP may not be optimal)

Indications ( 
JACC
1998;32:840 &
Circ
2009;119:e391)

•
Diagnosis and evaluation

Ddx of shock (cardiogenic vs. distributive; esp. if trial of IVF failed or is high risk) and of pulmonary edema (cardiogenic vs. not; esp. if trial of diuretic failed or is high risk)

Evaluation of CO, intracardiac shunt, pulmonary HTN, MR, tamponade

Evaluation of unexplained dyspnea (PAC during provocation w/ exercise, vasodilator)

•
Therapeutics
(
Circ
2006;113:1020)

Tailored therapy to optimize PCWP, SV, S
_v
O
₂
in heart failure (incl end-stage) or shock

Guide to vasodilator therapy (eg, inhaled NO, nifedipine) in pulm HTN, RV infarction

Guide to perioperative management in some high-risk Pts, pretransplantation

•
Contraindications

Absolute
: right-sided endocarditis, thrombus/mass or mechanical valve; PE

Relative
: coagulopathy (reverse), recent PPM or ICD (place under fluoroscopy), LBBB (~5% risk of RBBB → CHB, place under fluoro), bioprosthetic R-sided valve

Efficacy concerns (
NEJM
2006;354:2213;
JAMA
2005;294:1664)

• No benefit to routine PAC use in high-risk surgery, sepsis, ARDS

• No benefit in decompensated HF ( 
JAMA
2005;294:1625); untested in cardiogenic shock • But: ~½ of CO & PCWP clinical estimates incorrect; CVP & PCWP not well correl.; ∴ use PAC to (a) answer hemodynamic ? and then remove, or (b) manage cardiogenic shock
Placement

• Insertion site:
R internal jugular
or
L subclavian veins
for “anatomic” flotation into PA •
Inflate
balloon (max 1.5 mL) when
advancing
and to
measure PCWP

• Use resistance to inflation and pressure tracing to avoid overinflation & risk of PA rupture •
Deflate
the balloon when
withdrawing
and at all other times • CXR should be obtained after placement to assess for catheter position and PTX

• If catheter cannot be successfully floated (typically if severe TR or RV dilatation) or if another relative contraindication exists, consider fluoroscopic guidance
Complications

•
Central venous access
: pneumo/hemothorax (~1%), arterial puncture (if inadvertent cannulation w/ dilation → surgical/endovasc eval), air embolism, thoracic duct injury •
Advancement
: atrial or ventricular arrhythmias (3% VT; 20% NSVT and >50% PVC), RBBB (5%), catheter knotting, cardiac perforation/tamponade, PA rupture •
Maintenance
: infection (esp. if catheter >3 d old), thrombus, pulm infarction (≤1%), valve/chordae damage, PA rupture/pseudoaneurysm (esp. w/ PHT), balloon rupture
Intracardiac pressures

• Transmural pressure (
preload) = measured intracardiac pressure – intrathoracic pressure • Intrathoracic pressure (usually slightly
) is transmitted to vessels and heart •
Always measure intracardiac pressure at end-expiration
, when intrathoracic pressure closest to 0 (“high point” in spont. breathing Pts; “low point” in Pts on
pressure vent.) • If ↑ intrathoracic pressure (eg, PEEP), measured PCWP
overestimates
true transmural pressures. Can approx by subtracting ~½ PEEP (× ¾ to convert cm H
₂
O to mmHg).

• PCWP: LV preload best estimated at
a
wave; risk of pulmonary edema from avg PCWP

Cardiac output

•
Thermodilution
: saline injected in RA. Δ in temp over time measured at thermistor (in PA) is integrated and is
1/CO. Inaccurate if ↓ CO, sev TR or shunt.