Incidence and predictors of postoperative deep vein thrombosis in cardiac surgery in the era of aggressive thromboprophylaxis.

BACKGROUND

Deep venous thrombosis (DVT) is a well-known complication of surgery but its significance in cardiac surgery is not well defined. We reviewed the results of a prospective observational protocol for repeated postoperative lower extremity duplex venous scans (DVS) screening starting on postoperative day 3-4 through hospital discharge.

METHODS

A total of 1,070 (88%) of the 1,219 overall unique adult cardiac surgery patients at our institution (August 2005 to December 2007) underwent DVS screening. The 149 exclusions included 15 due to early death (1.2%); 39 with a history of preoperative DVT (3.2%) and 93 missed patients (7.6%). All patients underwent maximally aggressive thromboprophylaxis as stipulated by the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition), and complemented with postoperative clopidogrel in coronary artery bypass grafting patients.

RESULTS

A positive DVS (within 30 days of surgery) for at least 1 lower extremity DVT was observed in 139 of 1,070 eligible patients (DVT: 13.0%). Incidence of DVT was similar in coronary artery bypass grafting (118 of 948; 12.4%) and valve (33 of 237; 13.9%) patients. Hemorrhagic complication requiring reexploration occurred in only 19 patients (1.8%) despite thromboprophylaxis. The DVT cohort showed significantly worse operative (in-hospital or <30 days) mortality (DVT: 9 [6.5% vs no DVT: 16 [1.7%];] p < 0.003), postoperative hospital stay (14.4 +/- 12.9 vs 8.3 +/- 7.3 days; p < 0.001), and 30-day hospital readmissions (20.9% vs 10.3%; p = 0.001). Multivariate logistic regression predictors for developing DVT were increased age (odds ratio [OR; 95% confidence interval = 1.24 (1.07 to 1.41) per 10-year increments]), blood transfusion (OR = 2.24 [1.49 to 3.39]), initial time on the ventilator/prolonged mechanical ventilation (OR = 1.02 [1.01 to 1.04] per 10-hour increments), and need for reintubation (OR = 2.57 [1.48 to 4.47]).

CONCLUSIONS

A considerable number (13%) of cardiac surgery patients develop otherwise silent DVT despite maximal thromboprophylaxis. Aggressive mechanical and pharmacologic thromboprophylaxis in this population appears safe and indicated. Whether routine postoperative DVS screening alters patients' outcomes and is cost effective remains undefined, but should be considered in case of a complicated-prolonged postoperative course.