Though the ACC/AHA guidelines set up the standard algorithm for preoperative cardiac assessment in non-cardiac surgery, its adherent rate was not known. In this study, we confirmed that preoperative TTE in elderly patients with hip fracture is frequently not according to these guidelines in daily practice. A large number of patients are receiving unnecessary preoperative TTE without detecting the major cardiac abnormality. Although no significant difference in postoperative complications was identified, those patients with preoperative TTE out of guideline had the longer time to surgery and longer total hospital length of stay.
Based on the ACC/AHA guidelines, the patients who require noninvasive cardiac testing are those with active high-risk cardiac conditions. High risk patients might benefit from delaying hip fracture surgery to assess or clear the cardiac comorbidities. However, delaying surgery due to unrecommended TTE could lead to worse outcome. As our results showed, patients who had the TTE out of guidelines had higher prevalence of chronic obstructive pulmonary disease compared with the patients without TTE. However, there was no significant difference in cardiac related factors, including history of cardiovascular disease or ASA class. One possible explanation was that the indications for TTE were unclear and were rarely adherent to guidelines in clinical practice. Thus, a standardized protocol to determine which patients should undergo TTE was extremely valuable in clinical practice.
Unnecessary surgery delay(＞48h) increases the perioperative complications and mortality. Patients without preoperative TTE was closed to this target time; however, those with TTE out of guideline were delayed almost 2 days. Previous studies have also shown a growing concern with surgery delay due to preoperative cardiac test. Luttrell et al. evaluated the impact of preoperative TTE on the elderly hip fractures (131 patients with TTE, 563 patients without TTE). They concluded that the patients with preoperative TTE had obvious longer waiting time to surgery. Harun et al. reviewed the effect of preoperative non-invasive cardiac test on hip fracture patients and found that further cardiac test led to a significant delay to surgery. Cluett et al. compared the outcomes between the patients with cardiac evaluation besides electrocardiograph (22 patients) and the control group with only electrocardiograph (86 patients), which found the patients with further cardiac test had obvious surgery delay.
Therefore, we need to balance the benefits of TTE for preoperative cardiac risk assessment and the morbidity caused by surgery delay. High risk patients may benefit from delaying hip fracture surgery to undergo TTE and optimize the cardiac comorbidities. However, delaying surgery with a preoperative TTE that is not recommended or contributing may lead to worse outcome. Although ACC/AHA guideline had set up the criteria to determine which patients need preoperative TTE in non-cardiac surgery, its accuracy of acting as a screening tool to identify high risk patient with major cardiac abnormality was rarely studied. Our study demonstrated that the sensitivity of ACA/AHA guidelines for identifying patients who may have major cardiac abnormality with the potential to modify anesthesia or medical management was as high as 86.7% and the specificity was 68.7%. Our results supported those of a similar study from Chris et al, they reviewed 100 patients with preoperative TTE and found 66% was in accordance with the guideline. The sensitivity and specificity of guideline for identifying patients who may have cardiac abnormality were 100% and 40%.
These guidelines were also proved to be effective to prevent the overuse of the other cardiac test. Stitgen et al. found that only 29% of geriatric patients with hip fracture who received a cardiology consultation had met the ACC/AHA guidelines and the consultation out of guideline did not change perioperative management but caused prominent surgery delay. Smeets et al. conducted a retrospective study involving 388 patients and found the most frequent reason for incorrect preoperative cardiac screening was overscreening. In addition, the delay to surgery was increased by 9.9 h in the case of overscreening. Recently, Smeets et al. published the prospective study involving 166 hip fracture patients and 87% of patients received preoperative cardiac screening in adherence to guideline, which was associated with a diminished use of preoperative resources.
To our best knowledge, there was only one study evaluating the correspondance between guideline and TTE utilization before. However, they divided the patients into 2 groups (with TTE and without TTE) without further subdividing based on whether adhering to guidelines or not. The further subdivision could eliminate other unwanted distrubance, making the result difference more solely caused by TTE out of guideline. In addition, the pericardial effusion was not regarded as the abnormality with potentiality to change management, but it was proved to affect perioperative management in recent study. Our study showed implementation of guidelines could improve the approriate usage of preoperative TTE test, reduce unecessary surgery delay. Several limitations should be noticed when interpreting these results. Firstly, surgery delay is multifactorial not solely caused by the TTE test, however we tried to minor the bias by excluding patients with surgery delay due to the unavailability of an operating room, surgeon or anticoagulant withdrawl. Secondary, evaluating whether TTE was adherent to guideline or not was subjective, but we decreased the bias by assessing the cases by two iddependant observers (X.P.C, Y.C.M) blinded to the TTE result and disscussed with the third observer(QT.L) when they have different opinions and drawed the conclusion finally. Thridly, we mainly focused on whether TTE identify major cardiac abnnormality which was proved to change management in previous literature, this may overlook the other infromations provided on TTE.