Preoperative risk evaluation and stratification of long-term survival after valve replacement for aortic stenosis. Reasons for earlier operative intervention.

Predictability of prognosis was analyzed in 630 patients who were alive 30 days after valve replacement (1965-1986) for aortic stenosis. Follow-up totaled 4,072 patient-years. During the operative periods of 1965-1971 (n = 62), 1972-1976 (n = 164), 1977-1981 (n = 158), and 1982-1986 (n = 246), decreases in cardiothoracic index (0.56 +/- 0.06, 0.53 +/- 0.06, 0.52 +/- 0.06, and 0.51 +/- 0.06; p less than 0.0001), in the prevalence of functional classes III and IV (87%, 76%, 68%, and 62%; p less than 0.0001), and of left ventricular (50%, 39%, 36%, and 30%; p less than 0.05) were accompanied by improved survival (5 year/10 year +/- SE: 73 +/- 6%/53 +/- 6%, 82 +/- 3%/65 +/- 4%, 89 +/- 3%/79 +/- 4%, and 87 +/- 3%/-; p = 0.002) despite increasing age (56 +/- 9, 57 +/- 11, 59 +/- 10, and 61 +/- 11 years; p less than 0.01). A Cox regression analysis identified peak-to-peak systolic gradient (p = 0.0001; inversely related to death rate), cardiothoracic index (p = 0.0003), left ventricular failure (p = 0.0005), prosthetic orifice diameter of 15 mm or less (p = 0.001), age (p = 0.003), ventricular ectopic beats (p = 0.004), male gender (p = 0.03), and antianginal/antiarrhythmic treatment (p = 0.03) as independent risk factors. A prognostic index calculated from the final Cox model stratified the patients into eight risk groups, having observed +/- SE/predicted/expected (matched background population) 10-year survival rates of 90 +/- 7% (n = 29)/94%/91%, 84 +/- 6% (n = 61)/89%/87%, 86 +/- 3% (n = 105)/83%/81%, 75 +/- 4% (n = 165)/75%/77%, 62 +/- 6% (n = 128)/63%/74%, 51 +/- 8% (n = 84)/47%/71%, 29 +/- 9% (n = 40)/31%/67%, and 16 +/- 9% (n = 18)/14%/54% (p less than 0.000001/-/-). Excess mortality relative to the background populations prevailed predominantly in risk groups 5-8 and was mainly caused by congestive heart failure. Thus, improved long-term survival during the 22-year operative period was related to improved preoperative patient status. Earlier operation (= low prognostic index) inferred a survival rate comparable to that of a matched background population. The prognostic index was probably predominantly related to preoperative myocardial damage that caused late predictable death from congestive heart failure.