CAT: Therapy: Stable Angina and Surgery

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STABLE ANGINA AND THE EFFECTS OF SURGERY

Clinical Bottom Line:

For patients with stable angina without left main coronary disease and not in the "high risk" group, overall 10 yr event-free (MI or death) survival is no better, and perhaps slightly worse, with initial surgery as compared with initial medical therapy.
Angina symptoms, quality of life and mortality are initially higher with those treated by initial surgery, but this difference is not significant by 10 years.
The subgroups in which overall survival will be improved by surgery are:
1. >50% Left main stenosis (NNT = 6, 2 year mortality)
2. 3 vessel disease or angina with LVEF <50% (NNT="6-8," 10 year mortality)
3. 2/3 high risk clinical factors: resting ST Ż, hypertension, MI.

Appraised by: J. Ringash, HN Lee, November 11th 1993

The Evidence: [1,2] Two large unblinded RCTs.

Study (n) with outcome Medical Tx CABG RRR ARR (95% CI) NNT

[1] VACS (n = 686);
All patients; 11 yr mortality
3 vessel with Ż LVEF; 11 yr mort.
2/3 clin. risk. factors; 11 yr mort.
Left main stenosis > 50%; 2 yr mort. -
.43
.62
.64
.32 -
.42
.50
.51
.15 -
.02
.19
.20
.53 -
.01 (-.04 to .06)
.12 ( .07 to .17)
.13 ( .07 to .18)
.17 ( .13 to .22 -
NS
8
8
6

[2] CASS (n = 780);
All patients; 10 year mortality
Angina (5 year assessment)
23 vessel with Ż LVEF; 7 yr mortality
-
.21
.44
.43 -
.18
.30
.25 -
.14
.29
.32 -
.02 ( -.01 to .05)
.14 ( .09 to .19)
.18 ( .13 to .22) -
NS
7
6

Study (n) with outcome	Medical Tx	CABG	RRR	ARR (95% CI)	NNT
[1] VACS (n = 686); All patients; 11 yr mortality 3 vessel with Ż LVEF; 11 yr mort. 2/3 clin. risk. factors; 11 yr mort. Left main stenosis > 50%; 2 yr mort.	- .43 .62 .64 .32	- .42 .50 .51 .15	- .02 .19 .20 .53	- .01 (-.04 to .06) .12 ( .07 to .17) .13 ( .07 to .18) .17 ( .13 to .22	- NS 8 8 6
[2] CASS (n = 780); All patients; 10 year mortality Angina (5 year assessment) 23 vessel with Ż LVEF; 7 yr mortality	- .21 .44 .43	- .18 .30 .25	- .14 .29 .32	- .02 ( -.01 to .05) .14 ( .09 to .19) .18 ( .13 to .22)	- NS 7 6

Comments:

Intention to analyze subgroups were declared "a priori" and was methodologically rigorous [3].
Objective assessment of STŻ in stress testing was significantly better at 1.5 years but not at 5 years.
There was significant crossover(35-40%) from initial medical therapy to later surgery in the studies but analysis was by intention to treat.

References:

VA Cooperative group; NEJM 1984:311(21):1333 (Eleven year follow-up)
CASS.
- NEJM 1984; 310(12);750 (MI and mortality)
- NEJM 1985; 312(26):1665 (Survival with low LVEF).
- Circulation 1984; 68(5): 939 (survival data); 951 (quality of life).
- Circulation 1990; 82:1629-1648 (10 yr follow up, survival); 1649-1658 (quality of life).
Oxman A, Guyatt G. A Consumer's Guide to Subgroup Analysis. Ann Int Med 1992;116(1):78.

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