Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (23 page)

cardiac: HF (↑ JVP, displ. PMI, S
₃
), murmurs, LVH (S
₄
, LV heave), PHT (RV heave, ↑ P
₂
)

vascular: ✓ for asymmetric pulses, carotid/vertebral/subclavian bruits; carotid sinus massage to assess for carotid hypersensitivity (if no bruits)

neurologic exam: focal findings, evidence of tongue biting; FOBT

•
ECG
(abnormal in
50%, but only definitively identifies cause of syncope in
10%)

Conduction: SB, sinus pauses/sinus arrhythmia, AVB, BBB/IVCD

Arrhythmia: ectopy, ↓ QT, preexcitation (WPW), Brugada, e wave (ARVC), SVT/VT

Ischemic changes (new or old): atrial or ventricular hypertrophy

Other diagnostic studies (consider based on results of H&P and ECG)

• Ambulatory ECG monitoring: if suspect arrhythmogenic syncope

Holter monitoring (continuous ECG 24–48 h): useful if
frequent
events arrhythmia + sx (4%); asx but signif. arrhythmia (13%); sx but no arrhythmia (17%)

Event recorder (activated by Pt to record rhythm strip): limited role as only useful if established prodrome (because must be Pt activated)

Loop recorders (continuously saves rhythm, ∴ can be activated
after
an event): useful for episodes (including w/o prodrome) likely to occur w/in month.

Implantable
loop recorders (inserted SC; can record up to 3 y): useful for infrequent episodes (<1/mo); recommended for recurrent syncope w/o prodrome

• Echo: consider to r/o structural heart disease (eg, CMP [incl HCMP & ARVC], valvular disease [incl AS, MS, MVP], myxoma, amyloid, PHT, ± anomalous coronaries) • ETT: esp. w/ exertional syncope; r/o ischemia-or catecholamine-induced arrhythmias • Cardiac catheterization: consider if noninvasive tests suggest ischemia • Electrophysiologic studies (EPS): consider in high-risk Pts in whom tachy or brady etiology is strongly suspected, but cannot be confirmed;

50% abnl (inducible VT, conduction abnormalities) if heart disease, but ? significance

3–20% abnl if abnl ECG; <1% abnl if normal heart and normal ECG (
Annals
1997;127:76)

• ? Tilt table testing: utility is debated due to poor Se/Sp/reproducibility; consider only if vasovagal dx suspected but can’t be confirmed by hx • Cardiac MRI: helpful to dx ARVC if suggestive ECG, echo (RV dysfxn) or
FHx of SCD

• Neurologic studies (cerebrovascular studies, CT, MRI, EEG): if H&P suggestive; low yield

Figure 1-6 
Approach to syncope

High-risk features (usually admit w/ telemetry & testing;
J Emerg Med
2012;42:345)

• Age >60 y, h/o CAD, HF/CMP, valvular or congenital heart dis., arrhythmias, FHx SCD

• Syncope c/w cardiac cause (lack of prodrome, exertional, resultant trauma) or recurrent • Complaint of chest pain or dyspnea; abnl VS or cardiac exam • ECG suggesting tachy or brady-induced syncope; Pt w/ PPM/ICD

Treatment

• Arrhythmia, cardiac mechanical or neurologic syncope: treat underlying disorder • Vasovagal syncope: no proven benefit for midodrine, fludrocortisone, disopyramide, SSRI ? 16 oz of H
₂
O before at-risk situations (
Circ
2003;108:2660)

no proven benefit w/ bB (
Circ
2006;113:1164)

? benefit w/ PPM if ≥3 episodes/2y & loop recorder w/ asystole >3 sec (
Circ
2012;125:2566)

• Orthostatic syncope: volume replete (eg, 500 mL PO q a.m.); if chronic → rise from supine to standing
slowly
, compressive stockings, midodrine, fludrocortisone, high Na diet
Prognosis (
Ann Emerg Med
1997;29:459;
NEJM
2002;347:878)

• 22% overall recurrence rate if idiopathic, else 3% recurrence • Cardiac syncope: 2-fold ↑ in mort., 20–40% 1-y SCD rate, median survival ~6 y • Unexplained syncope w/ 1.3-fold ↑ in mort., but noncardiac or unexplained syncope w/ nl

ECG, no h/o VT, no HF, age <45 → low recurrence rate and <5% 1-y SCD rate

• Vasovagal syncope: Pts not at increased risk for death, MI or stroke • ✓ state driving laws and MD reporting requirements. Consider appropriateness of Pt involvement in exercise/sport, operating machinery, high-risk occupation (eg, pilot).

INTRACARDIAC DEVICES

Cardiac resynch therapy (CRT)/Biventricular (BiV) pacing (Circ 2012;126:1784)

• 3-lead pacemaker (RA, RV, coronary sinus to LV); R>S in V
₁
suggests approp LV capture

• Synchronize & enhance LV fxn (↑ CO, ↓ adverse remodeling)

•
Indic
: LVEF ≤35% + NYHA II–IV despite med Rx + SR + LBBB ≥150 ms (also reasonable if
either
LBBB ≥120 ms
or
no LBBB but QRS ≥150 ms + NYHA III–IV); consider in AF, but rate cntl → ~100% vent capture; ? NYHA I w/ LVEF ≤30% + LBBB ≥150 ms; ? EF ≤50% w/ AVB + indic for PPM (
NEJM
2013;368:1585)

•
Benefits
: ↓ HF sx, ↓ HF hosp., ↑ survival (NEJM 2005;352:1539; 2010;363:2385)

Implantable cardiac defibrillator (ICD) (NEJM 2003;349:1836; JACC 2009;54:747)

• RV lead: defib & pacing (± antitachycardia pacing [ATP] = burst pacing > VT rate to stop VT); ± RA lead for dual chamber PPM. Wearable vest & SC ICD exist (Circ 2013;127:854).

•
Pt selection
(NEJM 2004;350:2151 & 351:2481; 2005;352:225; 2009;361:1427; Circ 2012;126:1784)

2° prevention: survivors of VF arrest, unstable VT w/o reversible cause (NEJM 1997;337:1576); structural heart disease & spontaneous sustained VT (even if asx)

1° prevention: LVEF ≤30% & post-MI
or
LVEF ≤35% & NYHA II-III (wait: ≥40 d if post-MI, ? until stabilized on meds for NICMP, or if presumed reversible)
or
LVEF ≤40% & inducible VT/VF;
life expectancy must be
>
1
y
; consider for HCM, ARVC, Brugada, sarcoid, LQTS, Chagas or congenital heart disease if risk factors for SCD

•
Benefits
: ↓ mortality from SCD c/w antiarrhythmics or placebo

•
Risks:
inapprop shock in ~15–20% at 3 y (most commonly d/t misclassified SVT); infxn

• ICD discharge: ✓ device to see if approp; r/o ischemia; 6-mo driving ban (✓ state law); if recurrent VT, ? drug Rx (eg, amio + bB, JAMA 2006;295:165) or VT ablation (NEJM 2007;357:2657); ablation at time of ICD ↓ risk of VT by 40% (Lancet 2010;375:31)

Device infection (Circ 2010;121:458; JAMA 2012;307:1727; NEJM 2012;367:842)

• Presents as
pocket infection
(warmth, erythema, tenderness) and/or
sepsis w
/
bacteremia