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N Suskin, D Massel, H Arthur, T Swabey, Ontario CR Pilot Committees

London, Ontario

PURPOSE: The Canadian Cardiovascular Society (CCS) grading scale is widely used to classify severity of effort angina. It has not traditionally included an asymptomatic category (grade 0). We explored the value of adding this new grade among a wide spectrum of patients with ischemic heart disease participating in standardized cardiac rehabilitation programmes (CRP) at 24 sites across Ontario.

METHODS: Clinical characteristics, risk profile, CCS grade (including 0), use of medications, exercise parameters (including Duke Treadmill Score) were recorded among 3518 patients at entry to the CRP. Outcomes were compared at 6 months for death and non-fatal cardiac events requiring hospitalization (recurrent MI, heart failure, angina, revascularization).

RESULTS: Compared with patients with CCS grade > 1, those with CCS 0 were more likely male (69 vs 62%, p=.0004) and post revascularization (72 vs 59%, p<.0001). Their cardiac risk profile tended to be more favourable: patients with grade 0 had more favourable Duke Treadmill Score (39 vs 29% low risk, p<.0001) and modified Framingham Risk Scores (15 vs 20% high risk, p=.001). Use of secondary prophylactic medications (aspirin, beta-blockers, ACE inhibitors and statins) was similar. After adjusting for age and sex the risk of any cardiac event was lower among those with CCS grade 0 versus 1+ (OR 0.47, 95% CI: 0.35-0.65, p<.0001) and especially for angina (OR 0.28, 95% CI: 0.17-0.48, p<.0001) and PTCA (OR 0.59, 95% CI: 0.35-0.98, p=.04). CCS class 0 remained predictive of cardiac events after adjustment for the Duke Treadmill Score.

CONCLUSIONS: The addition of CCS grade 0 to the traditional CCS scale has value in predicting a group at low risk for subsequent cardiac events among a broad range of patients with ischemic heart disease.


Ontario Ministry of Health