Results:

Mean age was 66 years, 76% were men, and 59% were smokers. Angina at rest was present in 50%, 21% had ST elevation and 9% ST depression, 61% had no coronary stenosis, and 25% had nonsignificant and 14% significant stenosis. Spasm-positivity by provocation occurred in more than 50%. Treatment included calcium channel blockers in 93%, nitrates in 49%, antiplatelets in 47%, statins in 33%, and beta-blockers in 4%. Multivariable Cox proportional hazard model selected seven predictors of major adverse cardiac events (MACE). The integer score was assigned to each predictor proportional to their respective adjusted hazard ratio: history of out-of-hospital cardiac arrest (4 points), smoking, angina at rest alone, organic coronary stenosis, multivessel spasm (2 points each), ST-elevation during angina and beta-blocker use (1 point each). According to the total score in individual patients, three risk strata were defined: low (score 0-2, n = 598), intermediate (score 3-5, n = 639), and high (score 6 or more, n = 192). The incidence of MACE in the low-, intermediate-, and high-risk patients was 2.5%, 7.0%, and 13.0%, respectively (p < 0.001). Cox model for MACE between the three risk strata also showed prognostic utility of the scoring system in various clinical subgroups. The average prediction rate of the scoring system in the internal training and validation sets was 86.6% and 86.5%, respectively.