Changes in QRS voltage in cardiac tamponade and pericardial effusion: Reversibility after pericardiocentesis and after anti-inflammatory drug treatment

Objectives The goal of this study was to define the association between low QRS voltage and cardiac tamponade or pericardial effusion and to assess th e reversibility of low QRS voltage after therapeutic procedures. Background It is unclear whether low QRS voltage is a sign of cardiac tampo nade or whether it is a sign of pericardial effusion per se. Methods In a prospective study design, we recorded consecutive 12-lead elec trocardiograms and echocardiograms in 43 patients who were referred to our institution for evaluation and therapy of a significant pericardial effusio n. Cardiac tamponade was present in 23 patients (53%). Low QRS voltage (def ined as maximum QRS amplitude <0.5 mV in the limb leads) was found in 14 of these 23 subjects (61%). Nine of these 14 patients were treated by pericar diocentesis (group A). Five patients received anti-inflammatory medication (group B). Group C consisted of nine patients with pericarditis and signifi cant pericardial effusion who had no clinical evidence of tamponade. Results In group A, low QRS voltage remained largely unchanged immediately after successful pericardiocentesis (0.36 <plus/minus> 0.17 mV before vs. 0 .42 +/- 0.21 mV after, p = NS), but QRS amplitude recovered within a week ( 0.78 +/- 0.33 mV, p <0.001). In group B, the maximum QRS amplitude increase d from 0.40 <plus/minus> 0.20 mV to 0.80 +/- 0.36 mV (p < 0.001) within six days. In group C, all patients had a normal QRS amplitude initially (1.09 <plus/minus> 0.55 mV) and during a seven-day follow-up (1.10 +/- 0.56 mV, p = NS). Conclusions Low QR voltage is a feature of cardiac tamponade but nt of peri cardial effusion per se. Our findings indicate that the presence and severi ty of cardiac tamponade, in addition to inflammatory mechanisms, may contri bute to the development of low QR voltage in patients with large pericardia l effusions. (J Col Cardiol 2001;38:219-26) (C) 2001 by the American Colleg e of Cardiology.