Here we reported the long-term follow-up with patients who underwent aortic prosthesis replacement with smaller prosthesis (size
21 mm) in china. A notable finding was produced that obesity (BMI
) was an independent predictor of late mortality in patients undergoing AVR with small prosthesis. Obesity group and overweight group had poor survival and higher proportion of NYHA Function III/IV compared to normal group.
Review of previous studies
There have been some different opinions in the published reports about the impact of BMI on outcomes after AVR, but specialized research on AVR with small prosthesis was scarce. Several studies demonstrated that BMI is an independent predictor of mortality and clinic events after AVR. Parwis [11
] revealed obesity as an independent predictor of hospital and longer mortality in patients who underwent valve surgery. William [12
] studied patients having AVR for AS with or without concomitant coronary artery bypass grafting and revealed a better survival in patients with low BMI compared to patients with higher BMI. On the other hand, others failed to found a significant effect of BMI on post-operative outcomes. Vinod [13
] reported patients with BMI 24 or less are at significantly increased risk of in-hospital and long-term mortality after cardiac valvular surgery. This high-risk patient population warrants careful risk stratification and options for less-invasive valve therapies. Robert [14
] found Increasing BMI has no independent association with worsened outcomes in the short or long term, and overweight patients have a survival benefit after surgery. So the relationship of BMI and long-term survival after AVR was controversial. The long-term survival research about BMI in small aortic root is rarely reported.
Impact of BMI on long-term mortality and NYHA classification
It is important to note that there may be some differences in AVR between China and Western countries; it is unknown whether this could affect the results of the research. For example, rheumatic disease accounted for the major etiology in this cohort although occurrence of degeneration was on the rise; mechanical valves were mostly used; and patients were younger and had less concomitant CABG.
In this study, we determined that obesity raised the long-term mortality, implying that higher BMI means higher risk of adverse outcomes for patients with small aortic prosthesis replacement. These results are consistent with some previous studies [11
]. In addition, a higher proportion of patients with poor cardiac function were observed in the obesity group at one year after surgery, and that distinction increased over time. These findings suggest that high BMI is a possible indicator of poor long-term quality of life for patients with small aortic roots. Numerous earlier studies [15
] concluded that NYHA class of the patients could be ameliorated within a short period after operation. Nevertheless those studies they failed to keep up with its change in subsequent years after AVR.
The long-term outcome of EOAI, LVEF, LVMI
Several factors such as EOAI, LVEF and LVMI may directly contribute to a higher class of NHYA class [17
] in obesity and overweight group. We expelled LVEF from the list due to its insignificant change along with BMI increase. In contrast, EOAI and LVMI turned out to be related with BMI in our investigation. As a result, EOAI may associate with cardiac function and influence postoperative life quality. We also found EOAI to be also an independent predictor of late mortality in this research, which was in accordance with previous researches [17
(considered as PPM) [21
] could lead to increased late mortality after AVR, and that’s why PPM should be avoided in patients with small aortic roots. It’s a challenge for surgeons to select the optimal type and size of prosthesis, so that proper EOAI could be maintained in obese patients. Although suprannular stentless valves have been applied in clinic recent years to increase EOAI and prevent PPM, there have been some discrepancies in the results [22
]. Annulus enlarging techniques, including Nicks procedure [1
], the Manouguian technique [2
] and the Konno procedure [3
], allow for the implantation of prosthetic valves 1 or 2 size larger than the original size of the aortic annulus [28
], and many studies have been frequently reported with good results, but some authors have reported increased operative mortality [28
], so there is still no agreement about annulus enlarging techniques.
Why does obesity affect the late mortality and NYHA functional class in patients with implantation of small aortic prosthesis? We attempted to throw light upon the question in the following aspects: obesity-related diseases, operation techniques and postoperative lifestyle. Being overweight or obese were associated with increased risk of underlying disease such as diabetes [29
], hypertension [30
], coronary artery disease [31
] and other chronic diseases [33
], which may increase the mortality in the long-term. We indicated in this research that diabetes, systemic hypertension and chronic lung disease were independent predictors of late morality in patients undergoing AVR with small prosthesis. So obesity-related disease should be taken into consideration in advance to evaluate risk of surgery and predict long-term outcomes for the patients.
According to the results in our study, we should reconsider the role of annulus-enlarging techniques even though they are often accompanied by increased morbidity and mortality after AVR. Such techniques may be meaningful to recommend as the best choice for the patients with obesity and relatively small aortic annulus requiring AVR, but implantation with small prosthesis, especially in younger patients [36
], can effectively increase the EOAI and improve the long-term outcome and life quality. So in the future we should work to perfect annulus-enlarging techniques, including reducing the cross-clamp time and the occurrence of complication.
It should be noted that in normal-weight group the EOAI and LVMI also worsened three years later in spite of lower later mortality. The main reason may be an increase in BSA. In this study, we were informed that many people gained weight after AVR due to being less active and an improper diet. Since height changed little after operation, accumulation of weight may bring about larger BSA. It is important to instruct patients with small prosthesis to keep fit and control weight, which could certainly benefit their health after AVR.