Pocket Medicine

CARDIOLOGY

CHEST PAIN

Initial approach

•  Focused history: quality & severity of pain; location & radiation; provoking & palliating factors; intensity at onset; duration, frequency & pattern; setting in which it occurred; associated sx; cardiac hx and risk factors

•  Targeted exam: VS (including BP in both arms), cardiac gallops, murmurs or rubs; signs of vascular disease (carotid or femoral bruits, ↓ pulses), signs of heart failure; lung & abdominal exam; chest wall exam for reproducibility of pain

•  12-lead ECG: obtain w/in 10 min; c/w priors & obtain serial ECGs; consider posterior leads (V7–V9) to reveal posterior MI if hx c/w ACS but ECG unrevealing or ST ↓ V1–V4

•  Cardiac biomarkers (Tn ± CK-MB): ✓ Tn at baseline & 3–6 h after sx onset troponin: >95% Se, 90% Sp; level >99th %ile w/ rise & fall in approp. setting is dx of MI detectable 1–6 h after injury, peaks 24 h, may remain elevated for 7–10 d in STEMI high-sens. Tn: 98% Se, 90% Sp w/in 3 h of admit, 90% Se w/in 1 h ( JAMA 2011;306:2684)

Causes for ↑ Tn other than ACS (= “type 1 MI”): (1) Supply-demand mismatch not due to Δ in CAD (= “type 2 MI”; eg, ↑↑ HR, shock, HTN crisis, spasm, HCM, severe AS), (2) non-ischemic injury (myocarditis/toxic CMP, cardiac contusion) or (3) multifactorial (PE, sepsis, severe HF, renal failure, Takotsubo, infilt dis.) (Circ 2012;126:2020)

CK-MB: less Se & Sp (skel. muscle, tongue, diaphragm, intestine, uterus, prostate), useful for dx of post-PCI/CABG MI or MI if Tn already elevated

•  CXR; other imaging (echo, PE CTA, etc.) as indicated based on H&P and initial testing

•  If low prob of ACS (eg,  ECG & Tn) & stable → noninvasive fxnal or imaging test

•  Coronary CT angio (CCTA): NPV 98% for signif CAD, but PPV 35% for ACS; helpful to r/o CAD if low-intermed prob of ACS. CCTA vs. noninv. fxnal test for ischemia → ↓ time to dx & LOS, but ↑ prob of cath/PCI, contrast exposure & ↑ radiation (NEJM 2012;366:1393 & 367:299; JACC 2013;61:880). “Triple r/o” CT angiogram for CAD, PE, AoD.