Clinical course and late prognosis of treated subacute massive, acute minor, and chronic pulmonary thromboembolism.

Thirty-eight patients with pulmonary embolic disease, other than acute massive pulmonary embolism, have been assessed clinically and by right heart catheterisation and pulmonary arteriography or pulmonary embo-lectomy. In addition, completefollow-up information was obtained in 92 per cent (35) ofpatients 1 to 8 years after their initial illness. On the basis of the history and the pulmonary arteriographic appearances, three subgroups are described-subacute massive, acute minor, and chronic pulmonary embolism. Patients with subacute massive disease rarely had a well-defined predisposing factor to thromboembolism, had pulmonary arteriograms indistinguishable from acute massive embolism, but had long histories mainly of exertional dyspnoea which contrasts with the characteristically short, dramatic histories of patients with acute massive embolism. These patients had higher pulmonary artery pressures than patients with acute massive embolism. Patients with minor embolism usually had a well-defined predisposing cause to thromboembolism and normal haemodynamic findings. Patients with chronic embolism rarely had a well-defined predisposing factor to thromboembolism, had pulmonary arteriograms easily distinguishable from other forms of embolic disease, and had the highest pulmonary artery pressures. The late prognosis of both acute minor and subacute massive embolism is good, recurrence of embolism is rare, and late pulmonary hypertension is not seen. In contrast, patients with chronic thromboembolic disease follow a progressively worsening course with persistent pulmonary hypertension, increasing right heart failure, and eventual death. Pulmonary embolic disease has a wide variety of clinical presentations. The definition of subgroups facilitates the understanding of the clinical presentation , the haemodynamic disturbance, the natural history, and the effect of therapeutic interventions. The variables which are important in defining these subgroups are the severity of embolism, which can best be assessed by pulmonary arteriography; the duration of embolism, which can only be assessed from the history; and the presence or absence of additional cardiorespiratory disease other than pulmonary embolism. We have defined four subgroups in terms of these variables; acute massive, subacute massive, acute minor, and chronic pulmonary embolism. Patients with acute massive pulmonary embolism present with a history of less than 48 hours' duration, have more than 50 per cent obstruction of major pulmonary arteries, and have usually had an acute episode of cardiovascular collapse. The clinical presentation of acute massive pulmonary embolism with and without additional cardiorespiratory disease, and the resultant haemodynamic disturbance , treatment, and long-term follow-up have previously been described (Sutton et al. This study is concerned with three further subgroups of patients with pulmonary …