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■ Left ventricular hypertrophy (see Figure 2.6)

■ May mimic or obscure ACS

■ Characterized by a large S wave in V 1 , V 2 , and tall R wave in V 5 , V 6

■ “Strain” pattern with asymmetrically inverted T waves in inferior and

lateral leads may also be present.

■ Pericarditis

■ Diffuse ST elevations in multiple regions

■ PR depression

Serum Markers

■ May be normal early despite ongoing ischemia

■ Become elevated in NSTEMI and STEMI (see Table 2.3)

■ Myoglobin

■ Early rise but poor specificity

■ Rises in 1–2 hours

■ Peaks in 4–6 hours

■ Normalizes in 24 hours

■ CK-MB

■ Not as sensitive or specific as troponin

■ Rises in 3–4 hours

■ Peaks in 12–24 hours

■ Normalizes in 1–2 days

■ May also be elevated in pericarditis, myocarditis, and skeletal muscle disease

CARDIOVASCULAR EMERGENCIES

FIGURE 2.12. Early repolarization ECG findings.

(Reproduced, with permission, from Fuster V, Alexander RW, O’Rourke, RA. Hurst’s The

Heart, 12th ed. New York: McGraw-Hill, 2008:303.)

TABLE 2.3. Timeline for Serum Markers in the Evaluation of ACS

MARKER RISES PEAKS NORMALIZES

Myoglobin 1–2 hr 4–6 hr 24 hr

CK-MB 3–4 hr 12–24 hr 1–2 d

Troponin 3–6 hr 12–24 hr 7–10 d

A normal ECG does notrule

out ACS.

The initial ECG is non-

diagnostic in the majority of

patients with MI.