The Clinical Impact of Cardiology Consultation Prior to Major Vascular Surgery

Annals of Surgery 2018, 267 (1): 189-195. doi: 10.1097/SLA.0000000000002014.

 Presented by: Dr S O’Beirn

Background

  • Cardiovascular complications are the leading cause of morbidity and mortality in adult patients undergoing major vascular surgery.
  • Despite the perceived benefit of preoperative Cardiology consultation in high risk patients the evidence for this and the guidance for which patients it would be of greatest benefit remain unclear.
  • This study aims to analyse the impact of pre-operative Cardiology consultation rates on the incidence of post-operative Myocardial Infarction (MI) at the individual and Hospital level.

 Design & Setting

  • Retrospective analysis of a large prospective multicentre observational registry based in 29 hospitals across the state of Michigan from Jan ’12 to Dec ’14.

Subjects

  • 5191 cases undergoing Open Peripheral Arterial Bypass (n=3037), Open Abdominal Aortic Aneurysm Repair (n=332) or Endovascular Aneurysm Repair (n=1822).
  • Cases excluded Emergency surgery, Carotid Endarterectomy or Stenting, Age <18 or BMI <10 or >80.

Intervention

  • Preoperative Cardiology consult defined as a documented Cardiology clinic or In hospital consultation within 6 months prior to the procedure.

Outcomes

  • Primary Outcome of Perioperative Myocardial Infarction (PoMI) defined as a rise in cardiac biomarkers combined with either Ischaemic symptoms, new Ischaemic ECG changes, pathological Q waves or Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.
  • Secondary Outcomes included the development of a dysrhythmia, congestive heart failure or cardiac arrest within the initial hospitalisation following the operation.

Results

  • Patients undergoing pre-operative Cardiology consultations had significantly higher rates of Perioperative MI (2.7% vs 1.47%, p=0.002).
  • No significant variation in mortality (1.57% vs 1.10%, p=0.147).
  • Huge variation in rates of Cardiology consultation across centres (6.9%-87.5%, median 53.3%).
  • Lower rate of Perioperative MI at the quartile of centres with the highest rate of consultations OR 0.52 (0.27-0.98, 95% CI, p=0.045).

Conclusions

  • Higher rate of PoMI amongst patients undergoing pre-operative Cardiology consultation, though this can likely be explained by these patients being at higher risk due to operative and patient factors.
  • No significant variation in rates of PoMI within quartiles when cases grouped according to Revised Cardiac Risk Index.
  • Reduction of PoMI seen in hospitals with higher rates of preoperative Cardiology consultation. The specific mechanism of this is unclear. Suggestion of “Hospital culture” as a factor.

Strengths

  • Large sample size at the patient level.
  • Reporting of negative results.
  • Clinically relevant question.

Weaknesses

  • Retrospective analysis of previously published data.
  • Acknowledged limited data on the outcome of preoperative consultations.
  • Significant cofounders unaccounted for (Intraoperative anaesthetic and fluid management, technical skill of the surgeon, critical care management).
  • Lack of cost analysis.
  • Potential for lack of generalisability given all centres within 1 state.
  • Significant inter-quartile variability within rates of PoMI among centres with low rates of preoperative consultation.
  • Multiple implications drawn from lower rates of PoMI amongst high preoperative consultation centres despite only just attaining significance at a 95% CI (p=0.045).

Implications

  • Based on this study, centres with higher rates of preoperative medical consultation have lower rates of perioperative complications, specifically perioperative MI amongst patients undergoing elective major Vascular surgery.
  • However, this is not demonstrated by this data on a patient level and the implication is that variation in hospital culture is a key confounder.

Potential for impact

  • Limited potential for impact as failure to demonstrate improvements in perioperative outcomes on the patient level and lack of suggestion as to which patient groups may benefit from undergoing preoperative consultation.