Recurrent pulmonary embolism. A prospective study

We have prospectively studied a series of 121 consecutive patients with venous thromboembolism (38 with pulmonary embolism, 83 with venous thrombosis of the lower extremities) searching for recurrences of pulmonary embolism despite adequate heparin therapy. A baseline ventilation-perfusion lung scan was obtained initially in every patient, whether the original diagnosis was pulmonary embolism or venous thrombosis. Repeat chest roentgenograms and lung scans were obtained routinely at eight days of heparin treatment. The primary trial endpoints were a finding of a clinically apparent recurrent pulmonary embolism, or laboratory evidence of subclinical pulmonary embolism. Eight items of clinical and laboratory information were recorded at admission and then correlated with the lung scan results. Recurrences were seen in seven of 38 patients with an original diagnosis of pulmonary embolism, and in five of 83 patients admitted because of venous thrombosis (p = 0.034). Recurrences were also more frequent in patients with a free-floating thrombus on venography (p = 0.014). The risk of new defects in patients with venous thrombosis and without free-floating thrombus was 3.05 percent, venous thrombosis with free-floating thrombus, 13.33 percent; patients with pulmonary embolism without free-floating thrombus, 11.42 percent; and with free-floating thrombus, 38.67 percent. Venography seems thus mandatory in patients with pulmonary embolism, as it recognizes a subgroup of patients at a high risk of recurrences.