ECG
CXR
ECG
CBC
Chemistry
PT/PTT
Troponin
CXR
Consider:
BNP
D-dimer vs. CTA<unk> 
BNP
D-dimer vs. CTA<unk> 
Consider differential diagnosis (see above) and rule out emergent causes
ACS: Consider using HEART Pathway
PE: See Pulmonary embolism by pretest probability
Acute chest pain
Acute coronary syndromes 
Unstable angina
STEMI
Acute dyspnea 
Non-STEMI
Acute dyspnea
Stable angina