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Update in perioperative cardiac medicine

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ABSTRACT

Recent studies have shed light on preoperative risk assessment, medical therapy to reduce postoperative cardiac complications (beta-blockers, statins, and angiotensin II receptor blockers [ARBs]), perioperative management of patients with coronary stents on antiplatelet therapy, and perioperative bridging anticoagulation.

KEY POINTS

  • Outcomes are worse in patients with poor functional capacity or stable angina, and these factors should be considered in preoperative risk assessment.
  • Perioperative use of beta-blockers may benefit only patients at highest risk and may harm other patients.
  • Statins seem to provide perioperative protection.
  • If an ARB is withheld for surgery, it should be restarted soon after.
  • For patients with a coronary stent, the type of stent and duration of dual antiplatelet therapy need to be considered before noncardiac surgery.
  • Bridging anticoagulant therapy should not be used in patients at intermediate or low risk of thromboembolism.


 

References

Perioperative medicine is an evolving field with a rapidly growing body of literature. Because physicians and patients are often concerned about cardiac risk, we focus this review on perioperative cardiology.

The information we present here is derived from presentations at the Perioperative Medicine Summit and the annual meetings of the Society of Hospital Medicine and Society of General Internal Medicine in 2016. We surveyed perioperative literature from January 2015 through March 2016 and chose the final articles by consensus, based on relevance to clinicians who provide preoperative evaluations and postoperative care to surgical patients.

We have divided this review into four sections:

  • Preoperative cardiac risk assessment
  • Medical therapy to reduce postoperative cardiac complications (beta-blockers, statins, and angiotensin II receptor blockers [ARBs])
  • Perioperative management of patients with a coronary stent on antiplatelet therapy
  • Perioperative bridging anticoagulation.

PREOPERATIVE ASSESSMENT OF CARDIAC RISK

Functionally independent patients do better

Visnjevac O, Davari-Farid S, Lee J, et al. The effect of adding functional classification to ASA status for predicting 30-day mortality. Anesth Analg 2015; 121:110–116.

Functional capacity is an independent predictor of perioperative death and is included in the algorithm of the current joint American College of Cardiology/American Heart Association (ACC/AHA) guidelines,1 but it is not in the Revised Cardiac Risk Index2 or the American Society of Anesthesiologists (ASA) classification.3

The study. Visnjevac et al4 performed a retrospective, observational cohort study of 12,324 patients who underwent noncardiac surgery, stratifying rates of all-cause mortality and 30-day postoperative complications based on ASA class and functional capacity.

The ASA physical status classification is defined as:

  • 1—Normal healthy patient
  • 2—Patient with mild systemic disease
  • 3—Patient with severe systemic disease
  • 4—Patient with severe systemic disease that is a constant threat to life
  • 5—Moribund patient not expected to survive without surgery.

Functional capacity was defined as the ability to perform all activities of daily living. It was prospectively assessed during the patient interview by pre-anesthesia personnel and entered into the database of the Veterans Affairs Surgical Quality Improvement Program.

Results. Within each ASA class, the mortality rate was significantly lower for functionally independent patients than for partially or fully dependent patients:

  • In class 2—odds ratio (OR) 0.14 for functionally independent patients
  • In class 3—OR 0.29 for functionally independent patients
  • In class 4—OR 0.5 for functionally independent patients.

The mortality rate was higher for dependent patients than for independent patients who were one ASA class higher, despite the higher class having greater rates of comorbidity.

Adding functional capacity to the ASA classification improved the area under the receiver operating curve from 0.811 to 0.848 (a perfect test would have a value of 1.0), suggesting that physicians should incorporate functional capacity into their preoperative evaluation, perhaps by increasing a patient’s ASA class to the next higher class if he or she is functionally dependent.

Angina portends poor outcomes

Pandey A, Sood A, Sammon JD, et al. Effect of preoperative angina pectoris on cardiac outcomes in patients with previous myocardial infarction undergoing major noncardiac surgery (data from ACS-NSQIP). Am J Cardiol 2015; 115:1080–1084.

Coronary artery disease is a risk factor for adverse perioperative outcomes, but the risk varies depending on whether the patient has had a myocardial infarction (and how long ago) and whether he or she has anginal symptoms (and how severe they are).

The study. Pandey et al5 used data from the American College of Surgeons National Surgical Quality Improvement Program to evaluate the impact of stable angina in 1,568 patients who underwent noncardiac surgery after a myocardial infarction.

Results. Postoperative myocardial infarction or cardiac arrest occurred in 5.5% of patients. The incidence was significantly greater in those who had anginal symptoms before surgery than in those without symptoms (8.4% vs 5%, P = .035); reintervention rates and length of stay were also higher in this group. In multivariate analysis, preoperative angina remained a significant predictor of postoperative myocardial infarction (OR 2.49, 95% confidence interval [CI] 1.20–5.81) and re­intervention (OR 2.4, 95% CI 1.44–3.82.

The authors cautioned against relying on predictive tools such as the Revised Cardiac Risk Index that do not consider stable angina and previous myocardial infarction as separate independent risk factors.

Implications for clinical practice. While functional capacity is an integral part of the ACC/AHA guideline algorithm,1 the findings of these two studies suggest that other current tools to calculate perioperative risk (ASA class and Revised Cardiac Risk Index) could be improved by including functional capacity and stable angina.

PERIOPERATIVE MEDICAL THERAPY

Beta-blockers help only those at high risk and may harm others

Friedell ML, Van Way CW 3rd, Freyberg RW, Almenoff PL. ß-blockade and operative mortality in noncardiac surgery: harmful or helpful? JAMA Surg 2015; 150:658–663.

Beta-blockers have been used perioperatively for nearly 2 decades to try to reduce rates of postoperative major adverse cardiovascular events. However, in view of recent trials, fewer patients are likely to benefit from this intervention than has been thought.

The study. Friedell et al6 retrospectively analyzed data from 343,645 patients in Veterans Affairs hospitals to determine the effect of beta-blockers on major adverse cardiac event rates after major noncardiac surgery. Beta-blockers were considered to have been used perioperatively if given any time between 8 hours before and 24 hours after surgery. The outcome studied was the mortality rate at 30 days.

The authors derived a novel risk score and used multivariate analysis to attempt to adjust for confounding factors. The risk score was based on four risk factors identified a priori:

  • Serum creatinine level > 2.0 mg/dL
  • Coronary artery disease
  • Diabetes
  • Surgery in a major body cavity (abdomen or chest).

Results. In this cohort, 43.2% of patients had received a beta-blocker. The unadjusted mortality rates by risk category for patients receiving or not receiving a beta-blocker were:

  • No risk factors: 1.0% with a beta-blocker vs 0.6% without
  • One or two risk factors: 1.7% vs 1.5%
  • Three or four risk factors: 2.3% vs 4.5%.

After adjustment for confounding factors, the 30-day mortality rate was higher in low-risk patients and lower in high-risk patients who received beta-blockers. Odds ratios for death in beta-blocker users (entire cohort) by risk category were:

  • No risk factors: 1.19
  • One or two risk factors 0.97
  • Three or four risk factors 0.76.

In the 3.8% of the total cohort who underwent cardiac surgery, beta-blockers had no significant effect—beneficial or harmful—in any risk group.

Jørgensen ME, Hlatky MA, Køber L, et al. ß-blocker-associated risks in patients with uncomplicated hypertension undergoing noncardiac surgery. JAMA Intern Med 2015; 175:1923–1931.

The study. Jørgensen et al7 investigated the association between chronic beta-blocker use for the treatment of hypertension and 30-day rates of mortality and major adverse cardiac events. Eligible patients (N = 55,320) were at least 20 years old and were undergoing any type of noncardiac surgery. The authors established that hypertension was present through use of an algorithm based on the International Classification of Diseases (10th edition). Patients with existing cardiovascular disease and renal disease were excluded. The authors used multivariate analysis to adjust for confounding factors.

Results. Twenty-six percent of the patients were on chronic beta-blocker therapy for hypertension. The mortality rate at 30 days was 1.93% in patients treated with a beta-blocker alone or in combination with other antihypertensive drugs; the rate was 1.32% for patients receiving any combination of renin-angiotensin system inhibitor, calcium antagonist, or thiazide, but no beta-blocker. Similarly, the 30-day major adverse cardiac event rates were 1.32% with beta-blockers and 0.84% without beta-blockers.

In subgroup analysis, each medication combination that included a beta-blocker was associated with higher rates of death and major adverse cardiac events than the same combination without a beta-blocker. Odds ratios for major adverse cardiac events with beta-blocker combinations ranged from 1.22 to 2.16 compared with regimens with no beta-blocker.

Implications for clinical practice. These two studies added to a growing chorus of concerns about the value and safety of beta-blockers in surgical patients. Friedell et al6 made an observation that was remarkably similar to one reported by Lindenauer et al8 in 2005: when patients were stratified by baseline risk of death, only those with the highest baseline risk benefited from beta-blocker therapy. Those in the lowest risk group actually were harmed by beta-blocker use, ie, the mortality rate was higher.

More interesting is the novel observation by Jørgensen et al7 that even in patients with no known cardiovascular disease who are on chronic beta-blocker therapy—presumably on stable doses and not solely for perioperative risk reduction—rates of mortality and major adverse cardiac events were higher than for patients not on chronic beta-blocker therapy.

The current studies support a cautious, selective approach to the perioperative use of beta-blockers—they should be used only in high-risk patients undergoing high-risk surgery, as has been proposed by the ACC/AHA.1

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