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The Beta Blocker and Clonidine Protocol

Lesson 3
Risk Stratification

6. Persantine Thallium as Risk Predictor, Take 2

Baron repeated the Mangano study, only with 457 patients, and found essentially the same results.

457 patients, you say? Hmm - could be statistically significant!

The most important preoperative predictors were known coronary artery disease and older age. They found that a prophylactic preoperative dipyridamole-thallium SPECT and radionuclide angiography for screening before surgery for patients at high risk for coronary artery disease, was unable to predict cardiac morbidity. So, should you spend the $9 billion dollars on a fancy test that can't predict who is going to have perioperative cardiac events?

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Baron et. al. NEJM 1994

bullet Prospective study was designed to identify predictors of cardiac risk in consecutive patients evaluated preoperatively with dipyridamole-thallium single-photon-emission computed tomography (SPECT) to assess myocardial perfusion and radionuclide angiography to measure left ventricular ejection fraction.
bullet Prospectively in 457 consecutive patients undergoing elective abdominal aortic surgery.
bullet Eighty-six patients (19 percent) had one or more of the following postoperative complications: prolonged myocardial ischemia (61 patients), myocardial infarction (22), congestive heart failure (20), and severe ventricular tachyarrhythmia (2).
bullet Twenty patients died postoperatively (4.4 percent), half of them from cardiac causes.
bullet Information about myocardial perfusion obtained from dipyridamole-thallium SPECT did not accurately predict adverse cardiac outcomes.
bullet The best correlates of cardiac complications were
definite clinical evidence of coronary artery disease
age greater than 65 years
bullet Measurement of the ejection fraction was useful only in the prediction of left ventricular failure.
bullet

CONCLUSIONS:

  • The presence of definite clinical evidence of coronary artery disease and older age were the most important preoperative predictors of an adverse cardiac outcome after abdominal aortic surgery.
  • The routine use of dipyridamole-thallium SPECT and radionuclide angiography for screening before abdominal aortic surgery may not be justified.
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Content by Art Wallace MD PhD
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