The novel analysis of high-frequency QRS components (HF/QRS) has been proposed in patients with chest pain (CP) referred for exercise tolerance test (ex-ECG). We sought to evaluate the prognostic role of exercise high-frequency QRS-analysis (ex-HF/QRS) in patients with recent-onset stable CP, in the emergency setting.Methods:
Patients with CP underwent ex-ECG. A decrease greater than or equal to 50% of the signal of HF/QRS intensity was considered as index of ischemia as ST-segment depression greater than or equal to 2 mm or greater than or equal to 1 mm associated with CP. Exclusion criteria were QRS duration greater than or equal to 120 milliseconds and inability to exercise. Baseline characteristics were adjusted with the propensity score matching specifying nearest-neighbor matching in cardiovascular risk factors and risk scores. The primary end point was the composite of coronary stenosis greater than or equal to 70% or acute coronary syndrome, revascularization, and cardiac death on the 6-month follow-up.Results:
Of 589 patients, 22 achieved the end point. On the univariate analysis, known cardiovascular disease, GRACE score, and ex-HF/QRS were predictors of the end point. On the multivariate analysis, only ex-HF/QRS was predictor of the end point (odd ratio, 28; 95% confidence interval [CI], 6-120; P < .001). Overall, the ex-HF/QRS when compared to ex-ECG showed higher sensitivity (91% vs 27%; P = .02), lower specificity (74% vs 86%; P = .09), and comparable negative predictive value (99% vs 97%; P = .78). Receiver operating characteristic curve analysis showed the larger area of ex-HF/QRS (0.83; 95% CI, 0.75-0.90) over ex-ECG (0.57; CI, 0.44-0.70) and GRACE score (0.65; CI, 0.54-0.76); P < .03 on C-statistic. Women showed the largest area (0.89; CI, 0.83-0.95; P < .03) vs the other clinical data.Conclusions:
In patients with CP, the novel ex-HF/QRS analysis has a valuable incremental prognostic role over ex-ECG, especially in women.