Distribution of pleural effusion in congestive heart failure: what is atypical?

OBJECTIVES: This study was performed to determine the distribution of pleural effusion between the right and left hemithorax in patients with uncomplicated congestive heart failure, and to determine whether left-sided pleural effusion actually constitutes an atypical distribution in congestive heart failure.
METHODS: The study group consisted of 120 consecutive patients with both clinical and radiographic evidence of uncomplicated congestive heart failure, and whose chest radiographs at the time of presentation also showed evidence of pleural effusion. The presence or absence of pleural effusion in the right and left hemithorax was recorded for each case, as was the size of each pleural effusion, and the distribution of pleural effusion in these 120 patients was entered into a 2 x 2 table and analyzed by chi2 analysis.
RESULTS: There were 207 total pleural effusions, with 105 on the right and 102 on the left. Isolated right-sided pleural effusions occurred in 18 patients, there were bilateral pleural effusions larger on the right than the left in 25, there were bilateral pleural effusions of roughly equal size on each side in 36, there were bilateral pleural effusions larger on the left side than the right in 26, and there were isolated left-sided pleural effusions in 15. The difference was not statistically significant (chi2 = 0.316; P < or = 1.0).
CONCLUSIONS: Left-sided pleural effusion is not an atypical finding in congestive heart failure and is not, in and of itself, an indication for further clinical or imaging evaluation.