Two causes in one patient for extremely low voltage on the electrocardiogram.

An 80-year-old woman is described with two different causes (pericardial effusion and cardiac amyloidosis) for low QRS voltage on the electrocardiogram. Total 12-lead QRS voltage (from the peak of the R wave to the nadir of either the Q or the S wave, whichever is deeper) was only 34 mm (10 mm standard in all leads), the lowest we have encountered among 331 previously reported patients with 10 different cardiac conditions.