An estimated 4.2 million people die within 30 days of surgery worldwide each year. A new study, published in the European Heart Journal [1] today (Thursday), suggests that deaths and serious heart disease might be prevented if some patients see a specialist heart doctor as part of their post-surgery care.
In this observational study, researchers studied a group of patients who had suffered heart damage during or immediately after non-cardiac surgery. A proportion were evaluated by a cardiologist, but the rest were not. Patients who saw a cardiologist were less likely to die in the following year and they were less likely to suffer a second serious heart condition such as a heart attack, heart failure or irregular heartbeat.
The study was by Dr Christian Puelacher, Dr Noemi Glarner and a team from the University of Basel, Switzerland, led by Professor Christian Müller. Dr Puelacher said: "With our aging population, surgery is increasingly common. Even when surgery is not on the heart, the heart is challenged by the stress of surgery, including anesthesia, blood loss, inflammation and changes in blood pressure. This can lead to perioperative myocardial infarction/injury, or PMI for short.
"In high-risk patients, such as those with pre-existing heart or vascular conditions, or those aged over 65, PMI occurs in approximately 15% of patients, usually without any symptoms. Despite its often-silent presentation, PMI is a strong predictor for complications and death in the days and months after surgery."
To investigate whether post-surgery complications and deaths could be prevented, the researchers made use of a 'natural experiment'; whether or not a cardiologist was available to assess patients as part of their care.
The study included a group of 14,294 patients who were having non-cardiac surgery, such as orthopaedic surgery, at University Hospital Basel or Cantonal Hospital Aarau, Switzerland, and were considered high risk for PMI because they were aged 65 or older or already had cardiovascular disease.
Following surgery, patients were given a blood test for their levels of troponin, a protein that is released when the heart is damaged, such as during a heart attack. The study then focussed on 1048 patients whose tests showed that they had suffered a heart attack or damage around the time of their operation, and who were treated on the surgical ward.
Of these, 614 patients (58.6%) were evaluated by a cardiologist. For the remaining 434 (41.4%), a cardiologist was not available, this could be because it was the weekend or a public holiday when fewer specialists are at work, or because care for more urgent patients had been prioritised. Although this type of study means that other factors could influence the outcomes for patients, researchers did all they could to take these factors into account.
A comparison of the two groups showed that patients who were seen by a cardiologist were 35% less likely to die within a year of their surgery and 46% less likely to suffer any serious heart problems, including heart attack, sudden heart failure, dangerously irregular heart rhythm or death from heart disease. These patients were also more likely to get heart imaging tests and to be prescribed stronger medications.
Dr Puelacher said: "Our study shows that having a cardiologist involved in a patient's care after PMI is associated with fewer serious heart problems and better survival one year later. Our results suggest that close teamwork between surgical and heart teams can improve outcomes after major surgery."
Dr Glarner added: "No prior research has examined this specific intervention with comparable rigor or sample size. However, this is an observational study, which cannot prove cause-and-effect, even with strong adjustments for other factors. As gold-standard, a randomised controlled trial is needed to ultimately confirm the results.
"Surgery is only carried out for good reason and following careful assessment of the risks, but complications do still occur. It's vital to screen for PMI in patients who are risk. Where signs of heart injury are found, a cardiologist can ensure patients get the monitoring and treatment they need."
The researchers are now running an implementation study of screening for PMI in hospitals across Switzerland and Austria, including work at Dr Puelacher's current institution, the Medical University Innsbruck.
In an accompanying editorial [2] Professor William Weintraub from Georgetown University, Washington DC, USA, and colleague said: "This is a valuable study concerning an important and potentially modifiable management issue in patients who sustain a PMI in hospital after non-cardiac surgery. The study was conducted rigorously, with careful prospective data collection and appropriate evaluation of outcomes using well-validated statistical analyses.
"While the statistical approaches to reduce bias were appropriate, it is not possible to account for unmeasured confounding variables. Though the hazard ratios for reduced MACE and all-cause mortality are impressive, they remain in a range (e.g. perhaps >0.5) where unmeasured confounders could account for the observed association.
"The authors were judicious in their conclusions, noting that this was an association and that the employment of a more systematic evaluation by cardiologists in the setting of PMI may be of clinical benefit.
"In summary, given these limitations and inevitable uncertainties, do the findings of this study provide sufficient justification to recommend that a cardiology consult be undertaken in the setting of post-surgical post-operative MI? The answer is, at least provisionally, yes. This study provides evidence of clinical benefit and there is no evidence of harm. It is highly likely that all stakeholders, including healthcare professionals, healthcare systems, and especially patients will favour a structured consultation by a cardiologist in this setting."
