In this nationwide study, we found that patients with a history of AS who had pancreatic cancer and were admitted for PD had a higher in-hospital mortality than patients without AS. Patients with AS who need a non-cardiac surgery present a tough clinical challenge. AS is a fixed obstruction of left ventricular emptying that results in left ventricular hypertrophy, poor compliance, and increased end-diastolic pressures due to alterations in the left ventricular myocardium . Therefore, these patients are more sensitive to any alterations in hemodynamics as a result of these modifications. Thus, patients with AS have a higher chance of clinical deterioration during anesthesia and surgery . Moreover, previous studies showed that patients with AS who undergo a non-cardiac surgery had a higher rate of postoperative cardiovascular complications [14–17]. This can result in increased intraoperative and postoperative complications and possibly increased mortality.
In our study, patients with AS who underwent PD had more comorbidities than patients without AS. This could have contributed to the increased in-hospital mortality in these patients. In a study done by Kelly et al., patients with preoperative cardiac comorbidities were found to have a higher rate of perioperative mortality and morbidity when undergoing pancreatic resection. However, this study only looked at patients with CAD and heart failure, but not at patients with valvular heart disease . Therefore, we recommend that in patients with AS, it is important to do a detailed preoperative evaluation prior to undergoing PD, as these patients may have a high operative risk and may potentially have worse clinical outcomes. Another potential factor that may contributed to the increased in-hospital mortality in AS patients undergoing PD is age. In our study, we found that patients in the AS group were significantly older than patients in the non-AS group. Generally, clinical outcomes are poor in elderly patients due to multiple reasons including poor functional status, frailty, more medical comorbidities, and a higher preoperative risk than younger patients [19, 20].
Our study showed that patients with AS had a statistically significant higher chance of cardiac arrest, which is one of the common complications seen in patients with AS undergoing a non-cardiac surgery as demonstrated by previous studies [21, 22]. Moreover, patients in the AS group had a significant higher chance of requiring mechanical ventilation during hospitalization, however, there was no difference in ICU admissions between both groups. Furthermore, our study demonstrated no significant difference in the LOS and hospital charges between the two groups.
There are several limitations of this study. Due to the nature of the NIS database, our observations reflect admissions and not individual patients. Therefore, the unit of analysis is admission. Given the inability to account for multiple admissions for a given patient in the NIS, our conclusions may be confounded by the risk of repeat hospitalization. Thus, our reported rates may be viewed as over-estimates of a per-patient admission rate. Mortality rates, however, are unlikely to be affected. Under-or over-coding can lead to misclassification, although a large number of patients in the database strongly mitigates against substantial misclassification bias. NIS undergoes data quality assessment annually to ensure the internal validity of the data. Moreover, patients in the AS group were not classified based on the severity of stenosis, as this can potentially affect the outcome. Additionally, observational studies may not be able to fully adjust for unmeasured confounding factors that might affect our estimates for the reported associations between in-hospital mortality and included covariates. Therefore, conclusions based on these observational data should be viewed as associational and not causal in nature. Finally, these observations pertain to the AS population in the US and may not be generalizable to other AS populations in other countries.
As a conclusion, patients with AS had an increased hospital mortality, cardiac arrest and ICU admissions compared to non-AS patients. Therefore, patients with concurrent diagnosis of AS and pancreatic cancer undergoing PD might warrant a closer observation. A multidisciplinary approach involving oncologists, surgeons, cardiologists and anaesthesiologists should be done to jointly develop an appropriate preoperative and postoperative evaluation and management for these patients in order to prevents such complications.