Interaction of systolic blood pressure and resting heart rate with clinical outcomes in takotsubo syndrome: insights from the International Takotsubo Registry. 
The present study aimed to determine the prognostic impact of resting heart rate (HR) and systolic blood pressure (SBP) in takotsubo syndrome (TTS).  Patients from the International Takotsubo Registry with complete data on HR and SBP were enrolled.  We analysed all-cause mortality and major adverse cardiac and cerebrovascular events (MACCE) in tertiles of HR (<77 b.p.m.,  77-94 b.p.m.,  >94 b.p.m.)  and SBP (<119 mmHg, 119-140 mmHg, >140 mmHg).  In addition, linear splines with interactions between HR and SBP were analysed.  The risk of all-cause mortality was higher in the second HR tertile (1.89, 1.15-3.10; P = 0.012) and the third HR tertile (3.01, 1.90-4.79; P < 0.001) than in the first tertile.  Similar effects were observed for MACCE.  Low SBP was related to an increased risk of all-cause mortality (P < 0.001) and MACCE (P = 0.002).  In a multivariable analysis of all-cause mortality, at HR >70 b.p.m.,  every 1 b.p.m.  increase in HR was associated with a 1.7% increase (P < 0.001), and every 1 mmHg increase in SBP up to 130 mmHg was associated with a 2% risk reduction (P < 0.001).  The risk of all-cause mortality thus was particularly elevated when low SBP occurred together with high HR.  High HR and low SBP are associated with an increased risk of all-cause mortality in TTS.  HR reduction might be worthy of being investigated as a therapeutic strategy for this condition and high HR and low SBP can be used to evaluate risk in this acute presentation of TTS.  ClinicalTrials.gov NCT01947621.