Distribution of pleural effusion in congestive heart failure.

To the Editor: The recent article by Woodring questioned the classic statement of predominantly right-sided pleural effusions in patients with congestive heart failure (CHF), on the basis of a study of 120 patients whose cardiac pleural effusions were equally distributed between the right and the left hemithorax. (1) More importantly, the author also concluded that left-sided effusion is not an atypical finding in CHF and is not, in and of itself, an indication for further clinical or imaging workup to find alternative causes. This latter point seems to contradict Light's recommendations (2) and consensus guidelines, (3) and may possibly influence practice trends. Therefore, we present our own experience with the radiographic distribution of cardiac pleural effusions in the largest clinical series to our knowledge.

In the last 12 years, we identified 221 of 1,515 consecutive patients who underwent diagnostic thoracentesis as having CHF, at the University Hospital Arnau de Vilanova (Lleida, Spain). The diagnosis of CHF was established by clinical criteria (presentation, pleural fluid characteristics, and response to therapy). Twenty-four patients were excluded from the analysis because posteroanterior chest x-rays were not performed or available. The final analysis group of 197 patients consisted of 98 (50%) males and 99 (50%) females, with a mean age of 77 [+ or -] 9 years. As shown in the Table, we found a statistically significant difference in the distribution of pleural effusion between the right and left hemithorax (102 versus 39, [chi square] = 27.26, P < 0.001), even when considering only unilateral effusions (62 versus 18, [chi square] = 24.20, P < 0.001). Seventy-seven percent of patients had effusions that occupied a third or less of the hemithorax in the posteroanterior radiographic view. When four clinical series comprising 441 patients with CHF are combined, (1,4,5) 304 (69%) patients had bilateral pleural effusions, 95 (21%) had unilateral right-sided effusions, and 42 (9%) had unilateral left-sided effusions (Table). However, radiographic identification of pleural effusion is insensitive and detects only moderate to large amounts of pleural fluid. In a study of 60 patients with decompensated CHF, chest CT was used as the gold standard for the presence or absence of pleural effusion. (6) As many as 52 (97%) of the 60 patients had pleural effusion: of these, 23 (44%) had equally bilateral effusion, 20 (38%) had right-sided predominant bilateral effusion, 2 (4%) had left-sided predominant bilateral effusion, 5 (10%) had right-sided effusion only, and 2 (4%) had left-sided effusion only. Again, [chi square] analysis shows a statistically significant difference between the right and left hemithorax (25 versus 4, [chi square] = 15.20, P < 0.001).

To conclude, pooled data demonstrate a great preponderance of bilateral pleural effusions in CHF, and approximately double numbers of unilateral pleural effusions on the right side than on the left. For this reason, contrary to the suggestion of Woodring, we think that in the context of CHF thoracentesis is indicated if more than a minimal unilateral effusion (particularly left-sided) exists. Acting on Woodring's advice may provide clinicians false reassurance when evaluating patients with unilateral left-sided effusions in the setting of heart disease, thus missing important causes of exudative pleural effusions such as pericardial disease, postcardiac injury syndrome or postcoronary artery bypass surgery, as well as comorbid conditions such as pulmonary embolism or pneumonia.

Jose M. Porcel, MD

Department of Internal Medicine

Arnau de Vilanova University Hospital

Lleida, Spain

Manuel Vives, MD

Division of Internal Medicine

Clinica Recoletas

Albacete, Spain

References

1. Woodring JH. Distribution of pleural effusion in congestive heart failure: what is atypical? South Med J 2005;98:518-523.

2. Light RW. Pleural effusion. N Engl J Med 2002;346:1971-1977.

3. Maskell NA, Butland RJ, Pleural Diseases Group, Standards of Care Committee, British Thoracic Society. BTS guidelines for the investigation of a unilateral pleural effusion in adults. Thorax 2003;58 (Suppl 2):ii8-17.

4. Peterman TA, Brothers SK. Pleural effusions in congestive heart failure and in pericardial disease. N Engl J Med 1983;309:313.

5. Weiss JM, Spodick DH. Laterality of pleural effusions in chronic heart failure. Am J Cardiol 1984;53:951.

6. Kataoka H. Pericardial and pleural effusions in decompensated chronic heart failure. Am Heart J 2000;139:918-923.

Table. Published series on the distribution of cardiac pleural effusions
assessed by chest radiography (a)

                                       Peterman and
                 Current   Woodring,   Brothers,     Sum of previous
                 series    2005 (1)    1983 (4)      series (b)

Right             62 (31)   18 (15)     2 (4)         82 (22)
Left              18 (9)    15 (12,5)   3 (5,5)       36 (10)
Bilateral R > L   40 (20)   25 (21)    16 (30)        81 (22)
Bilateral R = L   56 (28)   36 (30)    19 (35)       111 (30)
Bilateral L > R   21 (11)   26 (22)    14 (26)        61 (16)
Total            197       120         54            371

                 Weiss and
                 Spodick,   Sum of all
                 1984 (5)   series (c)

Right            13 (19)     95 (21)
Left              6 (9)      42 (9)
Bilateral R > L
Bilateral R = L  51 (73)    304 (69)
Bilateral L > R
Total            70         441

(a) Data are presented as No. (%). R = right: L = left.
(b) Difference between the right and left side is significant (163 vs
97, [chi square] = 16.75, P<0.001).
(c) Difference between unilateral right and left side is significant (95
vs 42, [chi square] = 20.5, P<0.001).