RESUMO
The causes of low voltage complexes on the electrocardiogram (ECG) are variable; however, they are not commonly discussed. An ECG with small QRS amplitudes may initially look unremarkable to the unwary, but some of the underlying conditions may be critical. Although imperfect, the ECG is still a useful, noninvasive and readily available tool for the screening of these underlying conditions. We present two cases with low voltage complexes in the ECG. The first case highlights how the findings on ECG and subsequent echocardiogram led to the diagnosis of a rare case of cardiac amyloidosis. In the second case, a screening electrocardiogram alerted the physicians to a life-threatening condition, that of a large pericardial effusion with cardiac tamponade.