Postoperative myocardial injury is particularly prognostic toward predicting long-term mortality after non-cardiac surgery in patients classified as low-risk preoperatively

Author: Sunil Vasireddi, MD, Additional authors^*

See the poster.

Introduction:

• Myocardial injury even in asymptomatic patients is common after non-cardiac surgery, estimated to occur in ~12-20% of patients within 1-week of surgery, or up to 27 million patients globally each year.
• The VISION trial demonstrated that among 15,000 patients, troponin-T elevation within 3-days post-surgery was strongly associated with 2.4-10.5 fold rise in all-cause mortality at 30-days commensurate with magnitude of elevation.
• Additional studies, including a meta-analysis, have supported this idea that even a mild troponin (troponin-I or troponin-T) elevation above normal after non-cardiac surgery independently portends a high mortality risk (OR: 3.4) within the 1st year after surgery.
• Per ACC/AHA guidelines, evaluation of postoperative troponin is a grade I recommendation when signs and symptoms of myocardial ischemia are present but is a grade IIb recommendation for routine screening.
• It has been suggested that high risk patients should be screened with a postoperative troponin measurement. Current preoperative risk stratification tools, such as RCRI and NSQIP, are designed for predicting risk in the immediate perioperative period and have only shown to have moderate discrimination toward 30-day risk.
• However, the role and performance of current preoperative risk assessments, RCRI and NSQIP, toward predicting postoperative troponin elevation and long-term mortality is unknown.

Hypothesis/Goal:

• We suspect that postoperative troponin elevation forebodes a high risk of all-cause mortality even in preoperatively low-risk patients.
• Postoperative troponin screening might present an underutilized opportunity to help reclassify patients toward mitigating long-term mortality risk.

Methods:

• Single-center retrospective chart review analysis of patients that had a troponin drawn postoperatively from 2011 to 2016 at the MetroHealth Medical Center.
• Primary Endpoint: All-cause mortality up to one-year post-surgery.
• Patient data was de-identified per institutional IRB protocol.
• The Ohio Department of Health provided official death records for those patients who were lost to follow up.
• Inclusion Criteria:
  1) Patients 40-80 years of age, who underwent non-cardiac surgery requiring an overnight hospital stay, and had a postoperative troponin-I drawn within 14 days of the index surgery.
  2) Determined to be at elevated risk for CVD: defined as either at least one major criteria or two minor criteria:
  a) Major criteria: history of documented CAD, diabetes mellitus, peripheral arterial disease (documented by ABI), ischemic stroke, current smoker
  b) Minor criteria: hypertension, hyperlipidemia (LDL>160 mg/dL) or current statin use, prior smoking history (in the last decade), renal insufficiency (eGFR<59 ml/min).
  Exclusion Criteria:
  Pulmonary embolism, traumatic injury involving the chest cavity, or those who underwent neurosurgical intervention.

Analysis Methods:

• Patients were determined to have troponin elevation if they had a troponin-I level of 2 times or above the upper limit of normal at our lab, which is >0.08 ng/ml.
• Individual NSQIP and RCRI preoperative risk scores were calculated for each patient.
• Patients were classified as high-risk preoperatively if risk score determined >1% risk for MACE (RCRI) and mortality (NSQIP).
• Kaplan-Meier survival analysis and odds-ratio with sensitivity/specificity analysis were performed.

Results:

Conclusions:

• Our work adds to the growing body of evidence that patients with postoperative troponin elevations have clinically significant long-term all-cause mortality.
• This study demonstrates that currently used preoperative risk assessment tools, RCRI and NSQIP, by themselves were poor predictors of risk for postoperative troponin elevations or 1-yr mortality.
• Our results do however show that compared to the general population, post-op troponin elevation in patients classified as low-risk preoperatively by RCRI and NSQIP portended a markedly increased 1-yr mortality (10 times vs 4 times) with improved sensitivity of 0.83 and moderate specificity.
• These results support the use of postoperative troponin screening even in preoperatively low-risk patients with the appropriate cardiovascular risk factors to better identify patients with a high long-term mortality risk who might best benefit from further evaluation and risk mitigation strategies.

Clinical Relevance:

• The utility of risk stratification tools, with or without postoperative troponin elevations, for prognosticating patients at high risk has been previously uncertain toward eventual management decisions and outcomes.
• Trials such as MANAGE suggest a trend to improving CV outcomes with anti-thrombotic therapy and have also highlighted the poor utilization of primary prevention strategies such as aspirin and statin in these patients.
• Patients with “low-risk” pre-op likely stand to benefit from reclassifying their CV risk status with the identification of MINS through post-op troponin screening.

Acknowledgments/Disclosures:
This work was supported, in part, by a grant from AHA Clinical Scientist Training Program (SKV).  Authors report no conflicts of interest or disclosures. We thank the Ohio Department of Health and the IRB office at MetroHealth Medical Center for their guidance.

*Sunil K. Vasireddi¹, Erica Pivato¹, Laurence James¹, Douglas Gunzler², Peter Leo¹, Meera Kondapaneni¹

¹Heart and Vascular Center, Department of Medicine, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH, USA

²Center for Health Care Research and Policy, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH, USA

Program Director: Meera Kondapaneni, MD, FACC

Program Coordinator: Brittany Markle