Critical role of pulmonary angiography in the diagnosis of pulmonary emboli following cardiac surgery

This study was conducted to identify patients at high risk of the development of Pulmonary Embolism (PE) after open heart surgery, to evaluate pertinent diagnostic methods, and to assess the mortality associated with this complication. We evaluated the records of 2,551 consecutive patients who underwent open heart surgery over a 10-year period to identify those patients in whom PE developed. All surgical reports, ventilation/perfusion scans, pulmonary angiograms, and autopsies from the same period were also reviewed. Preoperative and postoperative risk factors for pulmonary embolism were also analyzed, as well as the outcome of this complication in each type of surgical procedure. Pulmonary embolism was identified in 69 (2.7%) patients after open heart surgery, in 43 (62.3%) of whom the diagnosis was established within the first week of surgery. Factors associated with high incidence for PE were hyperlipidemia, congestive heart failure and heparin-induced thrombocytopenia (P < 0.001); obesity and prolonged mechanical ventilation (P < 0.005); and prior right heart catheterization by the femoral approach and prior PE and/or deep vein thrombosis (P < 0.05). The diagnosis of PE was established by a high-probability ventilation/perfusion scan in 25 patients, by pulmonary angiography in 42 (29 of whom had prior V/Q scan read as intermediate or low probability for PE) and by autopsy in two patients. The mortality rate in patients who had PE was 7.2%, while in those without this complication it was 3.2%. These findings suggest that aggressive approach for the diagnosis of PE by pulmonary angiography whenever the V/Q scan is not read as high probability is crucial in patients with recent open heart surgery; such approach may identify patients with PE at an early stage and may have an impact in reducing mortality incurred by this complication. This diagnostic assessment should be emphasized in the perioperative period, especially in patients with multiple significant and identifiable risk factors for PE.