The potential for normal long term survival and morbidity rates after valve replacement for aortic stenosis.

BACKGROUND AND AIM OF THE STUDY

The sequelae of early aortic valve replacement (AVR) for aortic stenosis (AS) are controversial, with an increasing body of opinion regarding the patient risk profile as having an influence on long term survival and prosthesis-related morbidity rates. We therefore undertook a comparison of the morbidity and mortality rates of the patients undergoing AVR at our institution over a 22 year period with those in the background population to establish whether early intervention leads to an increased incidence of either.

METHODS

A multivariate risk analysis of 630 consecutive patients with AS who were alive 30 days after AVR performed between January 1965 and December 1986 was completed. The patients had a mean age of 59 years (range 14-78 years), 98% received a mechanical prosthetic valve, and 71% were in functional classes III or IV preoperatively.

RESULTS

Relative to an age- and sex-matched background population, the patients suffered a slight excess mortality during the first postoperative year, and a significant excess mortality after the 12th year, which was primarily related to congestive heart failure (64% of deaths versus 25% during the first 12 years; p < 0.01). A multivariate Cox regression model allowed calculation of a prognostic index for each patient. The index divided the patients into three groups (from low to high index): group A (n = 195) had normal sex- and age-specific survival, group B (n = 165) had a slight late (> 12th year) excess mortality, while group C (n = 270) had significant excess mortality throughout the follow up. Multivariate risk analysis of thromboembolism (1.7%/pt-yr), anticoagulant related hemorrhage (1.5%/pt-yr), all prosthesis-related complications combined (4.2%/pt-yr), and sudden cardiac events (arrhythmia and myocardial infarct; 1.8%/pt-yr) identified variables underlying advanced preoperative heart disease, coronary artery disease and systemic hypertension as the decisive risk factors. The preoperative prevalence of these risk factors as well as the postoperative incidence of the complications differed significantly between the three patient groups; A < B < C. Incidence rates of stroke in the patients (95% confidence interval) and in sex- and age-matched background populations were: group A, 0.48 (0.13-0.83) and 0.34 %/pt-yr, respectively, group B, 1.07 (0.46-1.68) and 0.52%pt-yr, respectively, and group C, 2.28 (1.50-3.06) and 0.68%/pt-yr respectively. Similar results were obtained for incidence rates of myocardial infarct.

CONCLUSION

Operative intervention early in the course of AS, being equivalent to a favorable risk profile, may result in an age- and sex-specific normal long term survival, generally low rates of prosthesis-related complications and a normal incidence of the dominant thromboembolic and hemorrhagic events and of myocardial infarction.