Heterogeneity of efficacy by HbA1c was observed for the primary endpoint of angina frequency ( Pinteraction = .027 ) , the key secondary endpoint of SL NTG use ( Pinteraction = .030 ) , SAQ angina frequency ( Pinteraction = .001 ) , and SAQ treatment satisfaction ( Pinteraction = .025 ) with greater efficacy of ranolazine in those with higher HbA1c values , increasing continuously from HbA1c levels > 6.5 % .