Intra-operative tachycardia is not associated with a composite of myocardial injury and mortality after noncardiac surgery A retrospective cohort analysis

BACKGROUND Myocardial injury after noncardiac surgery (MINS) is a major contributor to peri-operative morbidity and mortality with a reported incidence of about 8%. Tachycardia increases myocardial oxygen demand, and decreases oxygen supply, and is therefore a potential cause of MINS. OBJECTIVE We tested the hypothesis that there is an association between intra-operative area above a heart rate (HR) of 90bpm and a composite of MINS and in-hospital allcause mortality. DESIGN Retrospective analyses. SETTING Major tertiary care hospital, Cleveland, USA. PATIENTS Adults having elective or nonelective noncardiac surgery and scheduled troponin monitoring during the first 3 postoperative days between 2010 and 2015. MAIN OUTCOME MEASURES All-or-none composite of myocardial injury (MINS), defined by a peak postoperative generation 4 troponin T concentration at least 0.03 ng ml(-1), and in-hospital all-cause mortality. RESULTS Among 2652 eligible patients, 123 (4.6%) experienced MINS within 7 days after surgery and 6 (0.2%) died before discharge. Intra-operative area above HR more than 90 bpm was not associated with the all-or-none composite of MINS and in-hospital mortality, with an estimated odds ratio (95% confidence interval) of 0.99 (0.97 to 1.01) per 1 h bpm increase in area above HR more than 90 bpm. Secondary outcomes were also unrelated to the composite, with estimated odds ratios (98.3% confidence interval) of 0.99 (0.98 to 1.00) for area above HR more than 80, 0.98 (0.92 to 1.04) for area above HR more than 100 bpm, and 0.96 (0.88 to 1.05) for maximum HR. CONCLUSION There was no apparent association between various measures of tachycardia and a composite of MINS and death, a result that contradicts previously reported associations between other measures of intra-operative tachycardia and MINS/ mortality. Published online 30 November 2018