DISCUSSION
The main finding of the present study is that surgery does not have a
negative impact on the basal frailty status of patients referred for
cardiac surgery. On the contrary, we have shown a significant
improvement in the overall burden of frailty 6 months after surgery.
This finding is true for both measurements that were employed to assess
frailty, the Fried frailty scale and the CFS. In this way, we can
confirm the dynamic and partially reversible nature of frailty in
patients referred for cardiac surgery.
Changes or transitions among the ordinal levels of frailty is frequent
in community-dwelling adults. As we get older, these transitions tend to
occur towards a progressively greater degree of frailty. However, in
frail patients who suffer a specific pathology for which there is an
effective treatment, we could speculate that once this pathology has
been treated effectively, the level of frailty will decrease to the
extent that this pathology was contributing to it. For example, and
focusing on cardiovascular medicine, the presence of heart failure
secondary to a certain valve disease promotes a decrease in the level of
the patient’s activity and energy consumption. These decrease in the
individual activity can favor the appearance of a certain degree of
sarcopenia, which constitutes a central etiological element in the
frailty pathophysiology. These events will have a direct negative impact
on each of the items that are evaluated by the Fried Scale, that is to
say: slow walking speed, muscle weakness, low physical activity, low
resistance to effort and weight loss. Conversely, once the valve disease
has been successfully treated and, therefore, the situation of heart
failure has been resolved, it is foreseeable that the postoperative
scores obtained in the different frailty scales will be improved
compared to the preoperative ones.
Our results are consistent with the previous arguments. Frail and
pre-frail patients showed a clear improvement in their postoperative
scores on four of the five items evaluated by the Fried scale.
Conversely, none of the 26 patients classified as robust with the Fried
scale presented significant deterioration in the scores evaluated by
this scale.
The reversibility of frailty was first shown in studies at community
level during the first years of the 21st century (27,28). As an example,
in the study of Binder et al. (27), 152 sedentary community-dwelling
people, with an average age of 83 years and with a previous screening of
mild or moderate frailty, were randomized to perform various strength,
balance and resistance exercises during 9 months. The individuals who
performed the exercises showed a marked improvement in their previous
frailty status, quantified by the modified PPT test (modified Physical
Performance Test), and in their functional capacity measured through the
basic and instrumental activities of daily life.
In the clinical setting and more specifically in the field of surgery,
very few studies have focused on changes in the patient’s frailty status
after the intervention. In 2015, McAdams et al. (29), with the aim to
“study the natural history of frailty after aggressive surgical
intervention such as kidney transplantation”, analyzed a prospective
cohort of 349 patients who were assessed for frailty using the Fried
scale before and after kidney transplant surgery. They showed that
frailty was increased during the first postoperative month (going from
19.8% to 33%), but it recovered its previous prevalence during the
second month and decreased in the third month (17.2%).
In the context of cardiac surgery, Jha et al. (20), published in 2017 a
study analyzing the preoperative and postoperative frailty status of 100
patients in whom either a heart transplant was performed, or a
ventricular assist device was implanted as a bridge to transplant.
Similarly to our study, the authors found that most frail patients who
survived the intervention showed a significant improvement in their
frailty status two months after surgery.
Therefore, considering our results, we could add a decrease in the
previous frailty status to the benefits provided by surgery, besides an
improvement in functional capacity and quality of life. This improvement
would translate into a lower risk for the occurrence of adverse
health-related outcomes, such as falls, disability, need for
hospitalization and dependency.
One limitation of the present study is the relatively low number de
patients included, however, it has been enough to demonstrate a decrease
in the global burden of frailty after surgery. Other limitation of the
study is that the follow-up period is limited to 6 months. It would have
been interesting to extend this period up to a year or more to see if
this improvement in frailty is consolidated or, on the contrary, it
tends to return to its preoperative values. As we have previously
published (19), frail patients present higher postoperative mortality
and morbidity rates. This could have led to a selection bias, as
patients who died tend to present higher levels of frailty. However,
this trend was only significative when frailty was assessed with the
Fried frailty scale.