Cardiovascular disease is common in South Africa, and anaesthesia is commonly required in these patients.

Cardiovascular disease is an important cause of morbidity in South Africa. Anaesthesia is commonly required in patients with coronary artery disease, hypertension and valvular heart disease. In South Africa, morbidity associated with coronary artery disease is now more common than that in the developed world. Hypertension is the second most important risk factor for death in South Africa.

Preoperative cardiovascular assessment for elective surgery (1)

The assessment of patients with cardiovascular disease should focus on three broad categories that determine perioperative cardiac outcome (Table I).

Patients who require preoperative cardiovascular evaluation

A thorough history, physical examination and selected investigations (ECG, serum creatinine) should identify patients who require further cardiovascular evaluation and optimisation prior to surgery (Table II).

If there is no indication for immediate cardiac or medical optimisation, then attention to both the severity and the combination of the medical risk factors, functional capacity and surgical risk (as shown in Table I) may mandate further investigation.

Medical condition of the patient

Medical examination should identify the presence of established risk factors of perioperative cardiac risk (Table III). These risk factors form Lee's Revised Cardiac Risk Index, (2) which has now superseded Goldman's classification. These risk factors are additive in predicting perioperative cardiac morbidity.

Surgical risk (1)

Patients undergoing low-risk surgery rarely warrant further investigation prior to surgery if they have none of the conditions shown in Table II. Low-risk surgery includes procedures such as cataract surgery, superficial procedures and breast surgery.

Vascular surgery is high-risk surgery associated with significant cardiac risk. In addition, intermediate-risk surgery such as intra-abdominal, intra-thoracic, major orthopaedic and head and neck surgery may all pose a cardiac risk, if the surgery is prolonged and associated with significant fluid shifts.

Functional capacity (1)

Patients who are asymptomatic with a good functional capacity are generally good surgical candidates. A history of being able to climb a flight of stairs is generally accepted as a marker of acceptable functional capacity. Patients who cannot do this or who get short of breath doing light work around the house should be considered to have poor functional capacity.

The decision whether to proceed with surgery

Postponement of surgery should only occur if it will potentially change the management (and hence hopefully improve the perioperative outcome) of the patient. Guidelines for whether it is appropriate to proceed to surgery are presented in Table IV. (1)

As can be seen from Table IV, the appropriateness of deferring surgery in the intermediate-risk patient with established cardiac clinical risk factors remains controversial. In these patients, a risk-benefit analysis is necessary. The potential benefit accrued by further investigation and subsequent medical therapy needs to be balanced against the morbidity associated with further investigation, and the morbidity associated with delaying the originally planned non-cardiac surgery (Table V).

Appropriate preoperative investigations

Further preoperative investigation is only appropriate if it provides:

* diagnostic information necessary to optimise or institute further medical therapy preoperatively

* diagnostic information necessary for appropriate perioperative management

* determination of baseline morbidity, which may be needed for further perioperative risk stratification.

Investigations that may be beneficial in determining further management are shown in Table VI.

Interventions that may improve perioperative cardiovascular outcome

The majority of patients presenting for elective non-cardiac surgery will proceed to surgery without the need for further preoperative evaluation or intervention. However, in patients who have cardiac risk factors and are undergoing intermediate-risk or vascular surgery, perioperative interventions may improve cardiac outcome (Table VII).1 It is important to appreciate that the care of the cardiac patient starts in the preoperative period and continues through into the postoperative period.

Other medical considerations

Hypertension

Deferring surgery in patients with essential hypertension presenting for elective surgery is appropriate if there is a hypertensive emergency. Patients who present with cardiac clinical risk factors and associated grade 3 hypertension (SBP [greater than or equal to] 180 mmHg and DBP [greater than or equal to] 110 mmHg) need a risk-benefit analysis based on the risk associated with delaying surgery for 4--6 weeks, in order to establish an appropriate response to modification of hypertensive therapy.

Previous percutaneous coronary revascularisation (1)

Patients who have had previous percutaneous coronary interventions are potentially at significant perioperative risk, as a result of haemorrhage (secondary to anti-platelet medication), thrombosis and myocardial infarction (associated with withdrawal of anti-platelet (thienopyridine) therapy) and late coronary restenosis. Perioperative considerations in these patients are presented in Table VIII. If surgery proceeds at an optimal time following a percutaneous coronary intervention, the patient should ideally receive perioperative aspirin, provided there is no contraindication.

Valvular heart disease

The management of patients with valvular heart disease is beyond the scope of this article. However, it must be appreciated that this group of patients require specific perioperative management of heart rate, preload, afterload and myocardial contractility according to the valvular lesion present.

Emergency surgery (1)

The need for emergency surgery that does not allow adequate time for further medical investigation and optimisation in a patient at cardiac risk ideally requires appropriate perioperative surveillance and management by a specialist anaesthetist. These patients would require further investigation and management of the cardiac condition in the postoperative period.

Considerations for the generalist practitioner

Unfortunately, not all patients with major clinical predictors requiring life- or limb-saving surgery have access to specialist anaesthetists. In this situation, the generalist should attempt to obtain specialist assistance. Transferral of the patient to a specialist anaesthetist or the procedure awaiting a specialist visit is only appropriate if it can be achieved within a clinically acceptable time period after discussion with a specialist anaesthetist. In the event of the generalist needing to proceed with emergency surgery and anaesthesia, telephonic advice before, during and after the operation can be very useful. The most experienced doctors in the hospital should perform the anaesthesia and surgery.

Conclusion

Patients at cardiac risk presenting for non-cardiac surgery require a methodical approach to preoperative risk stratification. Deferring of elective non-cardiac surgery, other than in patients with established unstable cardiovascular conditions, should only be considered after an appropriate risk-benefit analysis. The importance of simple measures such as adequate pain relief, normothermia and postoperative oxygen should not be forgotten in the patient at perioperative cardiac risk.

In a nutshell

* Cardiovascular disease is a leading cause of perioperative morbidity in South Africa.

* Unstable cardiovascular conditions need to be identified preoperatively and further evaluated.

* Unstable cardiovascular conditions include unstable coronary syndromes, decompensated cardiac failure, significant arrhythmias and severe valvular heart disease.

* Perioperative cardiac morbidity is related to the medical condition and functional capacity of the patient, and the extent of the surgery.

* Cardiac clinical risk predictors include a history of ischaemic heart disease, heart failure, stroke, diabetes and renal dysfunction.

* Patients undergoing low-risk surgery and patients with good functional capacity are generally good surgical candidates.

* One should always first consider the risk versus benefit before deferring an intermediate-risk patient.

* Attention to simple perioperative factors such as analgesia, temperature and postoperative oxygen is important.

* In high-risk cases anaesthesia must be provided by the most experienced doctor possible within the limitation of the health service.

Acknowledgements

Thanks to Professor M F M James and Dr P D Gopalan for constructive criticism and advice in the preparation of this manuscript. Any shortcomings in this review are, of course, of my making.

References

(1.) Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery: Executive Summary: A Report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): Developed in Collaboration With the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, and Society for Vascular Surgery. Circulation 2007; 116(17): 1971-1996.

(2.) Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999; 100(10): 1043-1049.

(3.) Wong EY, Lawrence HP, Wong DT. The effects of prophylactic coronary revascularization or medical management on patient outcomes after noncardiac surgery--a meta-analysis. Can J Anaesth 2007; 54(9): 705-717.

(4.) Devereaux PJ, Yang H, Yusuf S, et al. POISE. Perioperative Ischemic Evaluation Trial. http:// www.ccc.mcmaster.ca/Downloads/POISEAHAPresentation-November42007.pdf. Accessed 19 December 2007.

(5.) Biccard BM, Sear JW, Foex P. The pharmacoeconomics of peri-operative beta-blocker and statin therapy in South Africa. S Afr Med J 2006; 96: 1199-1202.

B M BICCARD, MB ChB, FCA(SA), FFARCSI, MMedSci Principal Specialist, Inkosi Albert Luthuli Central Hospital, KwaZulu-Natal

Bruce Biccard's major interests include cardiovascular assessment of patients for non-cardiac surgery, risk prediction and risk modification with perioperative medical therapy. He is also interested in the epidemiology of cardiovascular disease in South African vascular surgical patients.

Table I. Determinants of perioperative outcome (1)

* The medical (or cardiac) condition of the patient

* The extent of the planned surgery

* The functional capacity of the patient

Table II. Patients who need cardiovascular
evaluation prior to surgery (1)

Condition                         Example

Unstable coronary                 Recent myocardial infarction
  syndromes                         Unstable angina
Decompensated heart               Dyspnoeic at rest
  failure                           Worsening dyspnoea
Significant arrhythmias           Symptomatic arrhythmias
                                    High-grade bradycardias
                                    Ventricular tachycardias
Severe valvular heart disease     Particularly stenotic lesions

Table III. Risk factors associated with perioperative
cardiac morbidity (2)

* History of ischaemic heart disease

* History of heart failure

* History of stroke

* Diabetes

* Renal dysfunction (serum creatinine > 180 [micro]mol.[l.sup.-1])

Table IV. A step-wise approach to surgical decision making (based on
the ACC/AHA 2007 guidelines on perioperative cardiovascular
evaluation) (1)

Pre-operative assessment                            Action

** Life-threatening conditions
   identified (Table II)                            Defer
** Low-risk surgery                                 Proceed
** Good functional capacity                         Proceed
** Intermediate-risk surgery with indeterminate
  or poor functional capacity
  *** No cardiac risk factors (Table III)           Proceed
  *** 1 or 2 cardiac risk factors                   Proceed *
  *** 3 or more cardiac risk factors                Proceed *
** Vascular surgery                                 Refer to a
                                                    specialist
                                                    anaesthetist

* Deferring surgery in these patients can only be advocated if it is
believed that the results of a non-invasive investigation will change
the medical or perioperative management of the patient.

Table V. Examples of risk-benefit considerations associated with
preoperative cardiac interventions

Intervention              Risk-benefit considerations

Preoperative coronary     Higher mortality before planned
  revascularisation         non-cardiac surgery (3)
                            Only of benefit in patients with
                            medical indications for
                            coronary revascularisation

Perioperative             Increased perioperative all-cause
  beta-blockade (4)         mortality (POISE study data)
                          Increased perioperative stroke
                            Decreased perioperative myocardial
                            infarction

Delay in planned          Progression of surgical pathology, e.g.
  non-cardiac surgery       conversion of operable cancer to
  associated with           inoperable cancer
  intervention

Table VI. Considerations for further appropriate preoperative
investigations
24.5

                   Patients in whom it
Investigation      may be informative        Considerations

Resting echo-      Dyspnoea of unknown       May identify aetiology
cardiography         aetiology                 of dyspnoea

                   Worsening dyspnoea        A low resting ejection
                                               fraction is not
                                               necessarily
                                               associated with an
                                               adverse perioperative
                                               outcome

                   Cardiac murmur            Diagnosis of a specific
                                               valvular heart lesion
                                               allows for
                                               appropriate
                                               perioperative
                                               management

ECG                Patients with cardiac     In patients without
                     clinical risk factors     established CAD, an
                                               ECG may identify CAD

                   Vascular surgical         A baseline ECG is
                     patients                  useful for subsequent
                                               risk stratification
                                               in patients who
                                               develop perioperative
                                               myocardial ischaemia

Non-invasive       Patients who fulfil       Preoperative coronary
  stress testing     current medical           revascularisation is
  or coronary        indications               only of benefit in
  angiography                                  patients with
                                               established medical
                                               indications
CAD = coronary artery disease.

Table VII. Interventions which may improve perioperative
cardiovascular outcome (1)

Intervention            In whom is it           Appropriate anaes-
                        indicated               thetist for non-
Preoperative                                    cardiac procedure
  interventions

Coronary                Only patients with      All, provided 6 weeks
  revascularisation       medical indications     have elapsed since
                          for coronary            coronary
                          revascularisation       revascularisation

Perioperative beta-     Expected major          Specialist
  blockade                cardiac morbidity       anaesthetist
                          >10%5

Perioperative statin    All patients with       All
  therapy                 medical indications
                          for statin therapy

Intraoperative
  interventions

Effective pain          All                     All
  management

Normothermia            All                     All

Tight glucose           Patients at high risk   Specialist
  control                 of perioperative        anaesthetist
                          myocardial
                          ischaemia/vascular
                          patients

Haemodynamic            Expected                Specialist
  optimisation            perioperative           anaesthetist
                          mortality >20%
Postoperative
  interventions

Postoperative oxygen    All                     All

Postoperative ECG       Any patient with        All
                          possible
                          perioperative
                          ischaemia
Postoperative           All patients with       All
  troponins               possible
                          perioperative
                          ischaemia or ECG
                          changes

Table VIII. Managing patients with previous percutaneous coronary
interventions (1)

Percutaneous      Optimal time      Risk associated   Risk associated
  intervention      to non-           with early        with late
                    cardiac           surgery           surgery
                    surgery

Angioplasty       >2-4 weeks        Vulnerable        Restenosis of
                    <8 weeks          coronary          coronary
                                      plaque and MI     artery
Bare-metal
  stent           >4-6 weeks        Stent             Restenosis of
                                      thrombosis        stent
                                      and MI

Drug-eluting      >1 year           Stentthrombosis
  stent                               and MI

MI = myocardial infarction.