By Michael H. Crawford, MD, Editor
SYNOPSIS: This Swedish national study of longevity following aortic valve surgery showed that, overall, life expectancy declined by about two years, but was higher for patients younger than 50 years of age.
SOURCES: Glaser N, Persson M, Jackson V, et al. Loss in life expectancy after surgical aortic valve replacement. J Am Coll Cardiol 2019;74:26-33.
Durko AP, Kappetein AP. Long-term survival after surgical aortic valve replacement: Expectations and reality. J Am Coll Cardiol 2019;74:34-35.
Little information exists on the prognosis of patients after aortic valve replacement (AVR) compared to the general population. Investigators from Sweden conducted a national observational study to determine the long-term relative survival and estimated loss in life expectancy after AVR in all patients who underwent AVR from 1995 until the end of 2013.
Patients who underwent cardiac procedures other than concomitant coronary artery bypass graft surgery, those with infective endocarditis, and those who underwent emergent surgery were excluded. The outcome measures were survival, relative survival, and loss of life expectancy after AVR. For the second two outcomes, the expected survival from the Swedish general population (matched for age and sex) was used for a comparison. During the study period, 23,528 patients met the entry criteria. Mean age was 71 years, 40% were women, 58% had undergone isolated AVR, and 67% had received a bioprosthesis. During a median 6.8 years (maximum 19 years) of follow-up, the observed, expected, and relative survivals were 21%, 34%, and 63%, respectively. The overall loss of life expectancy was 1.9 years, but was highest in those younger than 50 years of age (4.4 years). There was no difference in loss of life expectancy between men and women. The authors concluded that patients with AVR have a shorter life expectancy compared to the general population — and it is substantial, especially at younger ages.
Traditionally, life expectancy after AVR has been compared to patients who met criteria for surgery, but were managed conservatively. Such comparisons clearly show an early increase in mortality due to the procedure, followed shortly by a life expectancy higher than the medically treated patients and similar to the general population. However, long-term life expectancy data are scarce for AVR patients, especially younger ones. Thus, this study is of considerable interest. It showed a decrease in life expectancy that ranged from half a year for patients older than 80 years of age at the time of AVR to almost five years for patients younger than 50 years of age.
The authors concluded that this is important information for counseling patients considering AVR. However, the authors of an accompanying editorial emphasized that this is a challenge for improving life expectancy after AVR.
To take up this challenge, cardiologists need to understand why there is a difference in life expectancy. Considering that this was a registry study, there was limited granularity in the data. The investigators noted an increased mortality in those with mechanical valves. However, when this was adjusted for age, the significant difference disappeared. Also, the authors demonstrated the effect of age at the time of AVR, which was directly related to survival, in that the older the patient, the more closely the survival rate was to the age-matched general population. In addition, gender did not influence the results. Finally, the authors extrapolated that 58% of patients died of complications from their prosthetic valve, but no further details were available. Thus, their data do not identify the exact cause of the decline in life expectancy. Prosthetic valve-related complications are a likely source of some of the lost life expectancy. Thromboembolism, structural failure, and infective endocarditis are common life-threatening complications. Also, many patients with aortic stenosis have coronary artery disease and other comorbidities that may differ from the general population. The younger patients in this series had more bicuspid valves. The associated aorta pathology or other issues unique to this population may explain some of their loss in life expectancy. In my experience, some patients believe they are cured after AVR and drop out of medical care, only to return when a complication occurs. Cardiologists must emphasize to AVR patients that they have traded a rapidly lethal disease for another less lethal one that requires ongoing medical care — if patients expect to realize the full potential of an AVR procedure.
In an accompanying editorial, Durko and Kappetein raised another possibility for improving life expectancy after AVR: choosing the optional time of surgery before left ventricular fibrosis is extensive. Of course, this means replacing valves in asymptomatic patients who meet certain criteria, which is never an easy sell. Current guidelines recommend AVR in asymptomatic aortic stenosis patients with reduced left ventricular function, an abnormal exercise test, or the need for cardiac surgery for another reason. Waiting in the wings for lack of compelling data are brain natriuretic peptide, MRI for fibrosis, severe calcification on CT scans, and reductions in left ventricular strain on tissue Doppler echocardiography. However, whether earlier surgery would improve life expectancy is unknown.