Meta-analysis of randomized controlled trials on safety and efficacy of exercise training in patients with abdominal...

Low exercise capacity preoperatively leads to increased postoperative complications, perioperative mortality, length of stay, and inpatient costs among patients going through elective abdominal aortic aneurysm (AAA) surgery. Therefore, exercise training may be extremely important for reducing perioperative adverse events in AAA patients. This paper aimed to perform a meta-analysis of randomized controlled trials to evaluate the safety of exercise training and its effects on exercise capacity in AAA patients.

We searched for randomized controlled trials published up to December 2017 that compared exercise training vs usual care without exercise training in AAA patients. The primary outcome was safety, specifically the occurrence of cardiovascular adverse events during the study. Secondary outcomes were changes in AAA diameter, inflammation markers, and exercise capacity based on peak oxygen consumption (peak V˙o₂) and anaerobic threshold (AT).

We identified 341 trials, and after an assessment of relevance, 7 trials with a combined total of 489 participants were analyzed. There were a total of two cardiovascular adverse events during the exercise test and training, and the cardiovascular event rate and its 95% confidence interval (CI) were 0.8% and 0.2% to 3.1%. Exercise training did not tend to increase AAA diameter, and it also tended to decrease high-sensitivity C-reactive protein level in patients with AAA. All studies that evaluated the changes in AAA diameter or high-sensitivity C-reactive protein level involved patients with AAA diameter <55 mm at baseline; there was no study involving participants with AAA diameter ≥55 mm at baseline. Exercise training significantly increased peak V˙o₂ (pooled mean difference, 1.67 mL/kg/min; 95% CI, 0.69-2.65; P < .001) and AT (pooled mean difference, 1.98 mL/kg/min; 95% CI, 0.77-3.19; P < .001) in AAA patients. The result of meta-regression suggested that the effects of exercise training on peak V˙o₂ and AT were not modulated by the exercise duration.

Our analyses suggested that exercise training among AAA patients is generally safe, although future research should be carried out to further clarify the safety among patients with large AAAs. Exercise training improved peak V˙o₂ and AT in AAA patients. More data are required to identify the optimal exercise duration for improving exercise capacity in patients with AAA.