Perioperative Cardiac Events In Patients Research Articles

Dipyridamole technetium-99m sestamibi myocardial tomography in patients evaluated for elective vascular surgery: Prognostic value for perioperative and late cardiac events

Dipyridamole thallium-201 myocardial imaging can provide information regarding risk of perioperative cardiac events in patients being considered for vascular surgery. The value for this purpose of myocardial imaging with technetium-99m sestamibi (MIBI), a radiotracer with biokinetic and imaging properties different from thallium-201, has not been established. To this end the prognostic value of dipyridamole MIBI tomography for perioperative and late cardiac events was evaluated in 229 consecutive patients being considered for elective vascular surgery. Vascular surgery was done ≤3 months after testing in 197 of these patients. Perioperative cardiac events (cardiac death, nonfatal myocardial infarction, unstable angina, or ischemic pulmonary edema) occurred in 9 (5%) patients. The rate of such events was 3% in patients with normal MIBI results, 5% in those with abnormal results, and 6% in patients with a reversible MIBI defect (both p = NS). When patients with abnormal MIBI results who had preoperative cardiac interventions (coronary revascularization or an increase in antiischemic medical therapy) were compared with those who did not, no significant differences in the occurrence of perioperative cardiac events were found between these two groups either. A group of 172 medically treated patients who survived vascular surgery and did not have a nonfatal perioperative cardiac event was then monitored (mean 21 ± 14 months) for the occurrence of a serious late cardiac event (nonfatal myocardial infarction or cardiac death). Event-free survival (Mantel-Cox) was significantly less in patients with abnormal studies compared with those with normal scan results. Late cardiac events occurred in 26 (15%) patients, with those having an abnormal MIBI result showing a significantly greater event rate than those with normal results (26% vs 4%, p < 0.0001). The rate of late cardiac events was 33% in patients with a reversible MIBI defect ( p < 0.001) and 23% in those with a fixed defect ( p < 0.03). Independent Cox multivariable predictors of increased risk of late cardiac events were a history of diabetes mellitus (relative risk [RR] 2.2, 95% confidence interval [Cl] 1.0 to 4.9), an abnormal MIBI study (RR 3.7, 95% Cl 1.2 to 11.4), and a reversible MIBI defect (RR 2.7, 95% Cl 1.2 to 6.1). We conclude that, although its ability to assess increased perioperative cardiac risk remains uncertain, dipyridamole MIBI tomography does provide important prognostic information regarding the risk of serious late cardiac events in patients having vascular surgery. The presence of an abnormal MIBI result, specifically one demonstrating a reversible perfusion defect, is associated with significantly increased risk.

1013-108 Is Persantine Thallium Scintigraphy Cost Effective and Reliable in the Preoperative Evaluation of Patients Referred for Peripheral Vascular Surgery?

Asymptomatic CAD has been shown to be associated with a high risk of perioperative cardiac events in patients (pts) undergoing surgery for peripheral vascular disease (PVD). Dipyridamole thallium (SPECT) scintigraphy (DTS) is considered the most useful screening test for stratification of these pts. Comparative prospective evaluation of various noninvasive tests for detection of latent CAD in PVD pts is lacking. In this study, 100 consecutive patients referred for PVD surgery were evaluated by DTS, low work load exercise treadmill test (ETT) and ambulatory ECG monitoring (AEM). Pts with abnormal findings on any of the three noninvasive tests were evaluated with coronary angiography (angio) for further stratification. Fifty-five pts had reversible perfusion defects on DTS. Of the 55 + pts with DTS, 49 had data on AEM with 39% having evidence of ambulatory ischemia; 48 of the 55 pts performed ETT with ischemia induced in 13%. Of the 41 pts with normal DTS findings, 12 (29%) had ischemia during ETT (n = 6) or AEM (n = 6); 64% of these pts had multi-vessel CAD by angio. Statistical modeling and analysis of important clinical variables, AEM ischemia, and angio findings were compared with DTS for predicting CAD. These analyses revealed that family hx of CAD, chest pain, smoking, age ≥ 65 years, and ischemia on AEM were highly predictive of CAD with a positive predictive value of 89% and a specificity of 92%. These findings suggest that a careful evaluation of clinical parameters and AEM results can provide reliable and clinically meaningful data predictive of significant CAD in pts referred for PVD surgery. Our data have demonstrated that the findings on DTS are not always reliable and its routine use might not be warranted in preoperative evaluation of patients with asymptomatic CAD referred for peripheral vascular surgery.

Dobutamine stress echocardiography: Clinical utility and predictive value at various infusion rates

Dobutamine stress echocardiography has increasingly been used to assess patients for coronary artery disease. Despite the popularity of this test, the optimal dose of dobutamine has not been established. The objective of this study was to assess the accuracy of dobutamine stress echocardiography at various infusion doses and its utility as a predictor of perioperative risk in patients undergoing a noncardiac surgical procedure. One hundred thirteen consecutive patients underwent dobutamine stress echocardiography, subsequent cardiac catheterization, and/or a noncardiac surgical procedure. Three patient groups were analyzed on the basis of peak dobutamine infusion rates (17 ± 4, 29 ± 2, and 40 ± 0 μg/kg/min, respectively). The three groups were comparable with regard to age, sex, ejection fraction, and severity of coronary artery disease. In group I, the sensitivity and specificity of dobutamine stress echocardiography were 74% and 33%, respectively, with a positive predictive value of 78%. In group II, the sensitivity and specificity improved to 84% and 78%, with a positive predictive value of 89%. In group III, the sensitivity and specificity were 86% and 80%, respectively, with a positive predictive value of 86%. In the noncardiac surgical group there was only one nonfatal cardiac complication among the 50 patients with a dobutamine echocardiogram, which was negative for evidence of inducible ischemia. In conclusion, this study demonstrates that dobutamine stress echocardiography should use an infusion rate of ≥ 30 μg/kg/min to optimize diagnostic accuracy relative to angiographic coronary artery disease. A test that shows no evidence of new, inducible ischemia predicts a low risk of perioperative cardiac events in patients undergoing noncardiac surgery, even at an infusion rate as low as 20 μg/kg/min.

Extent of jeopardized viable myocardium determined by myocardial perfusion imaging best predicts perioperative cardiac events in patients undergoing noncardiac surgery : Brown KA, Rowen M: J Am Coll Cardiol 21:325–330,1993

Extent of jeopardized viable myocardium determined by myocardial perfusion imaging best predicts perioperative cardiac events in patients undergoing noncardiac surgery : Brown KA, Rowen M: J Am Coll Cardiol 21:325–330,1993

Extent of jeopardized viable myocardium determined by myocardial perfusion imaging best predicts perioperative cardiac events in patients undergoing noncardiac surgery

Objectives. This study was undertaken to test the hypothesis that the risk of perioperative cardiac events is not simply determined by the presence of myocardium at risk, but is directly related to the extent of myocardium at risk as reflected in thallium-201 myocardial imaging.Background. The risk of perioperative cardiac events in patients undergoing noncardiac surgery has been related to the presence of transient defects on dipyridamole thallium-201 myocardial imaging, reflecting jeopardized viable myocardium.Methods. The study cohort consisted of 231 consecutive patients who underwent noncardiac surgery and had a preoperative dipyridamole thallium-201 imaging study. Patients with vascular reconstruction or bypass constituted the largest surgical subgroup (n = 140). For thallium-201 imaging data, each of three planar projections was divided into three segments (total nine segments) and each segment was interpreted as normal or showing a transient or fixed defect. The ability of clinical and thallium-201 imaging data to predict perioperative cardiac events was compared with stepwise multivariate logistic regression analysis.Results. Perioperative cardiac events occurred in 19 patients, including 5 with cardiac death, 7 with nonfatal myocardial infarction and 7 with unstable angina. For cardiac death or nonfatal myocardial infarction, the only significant multivariate predictors were the number of myocardial segments with transient thallium·201 defects (p < 0.0005) and a history of diabetes mellitus (p < 0.05). For all cardiac events, the only significant multivariate predictors were the number of myocardial segments with transient defects (p < 0.0001), diabetes mellitus (p < 0.05) and calcium channel blocker use (p < 0.05).Conclusions. The probability of important cardiac events in patients undergoing noncardiac surgery is best predicted by the extent of myocardium at risk as reflected on thallium·201 myocardial perfusion imaging. A history of diabetes mellitus also has a significant influence on perioperative risk.

Determination of perioperative cardiac risk by adenosine thallium-201 myocardial imaging

To determine the predictive value of adenosine thallium-201 myocardial imaging for perioperative cardiac events, 60 consecutive patients referred for preoperative cardiac evaluation were studied before vascular ( n = 25), orthopedic ( n = 14), or general ( n = 21) surgery. Tomographic ( n = 52) and planar ( n = 8) thallium-201 imaging was performed after adenosine infusion at a rate of 140 μg/kg/min for 6 minutes. Two blinded expert observers graded results of adenosine thallium-201 studies as normal (33%), fixed defect only (2%), reversible defect only (48%), and combined (fixed and reversible) defects (17%). After 8 ± 3 months of follow-up, 81% proceeded to surgery and 43% underwent preoperative coronary angiography. Clinical variables that correlated with perioperative cardiac events were a history of diabetes mellitus ( p = 0.05), left bundle branch block ( p = 0.02), and left ventricular hypertrophy ( p = 0.06) on the resting ECG. This clinically “high-risk” group had an event rate of 22% as compared with no cardiac events in patients in the “low-risk” group without these clinical characteristics ( p = 0.005). Stepwise logistic regression analysis revealed that the presence of a combined (fixed and reversible) adenosine thallium-201 defect ( p = 0.0007), three-vessel coronary artery disease ( p = 0.001), and left bundle branch block ( p = 0.02) was predictive of subsequent cardiac events with relative risk ratios of 4.9, 2.9, and 2.2, respectively. Therefore the presence of an adenosine thallium-201 perfusion defect is correlated with and predictive of an increased risk of perioperative cardiac events in patients referred for preoperative risk evaluation.

Silent myocardial ischemia monitoring predicts late as well as perioperative cardiac events in patients undergoing vascular surgery.

In a previous study we have shown that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at significantly increased risk for perioperative myocardial infarction. In the present study a group of 385 patients undergoing peripheral vascular surgery was studied long-term as well as short-term to determine whether perioperative monitoring for silent ischemia can identify those patients who are at significantly increased risk of late cardiac death or late cardiac complications as well as those patients at increased risk of perioperative myocardial infarction. All patients were monitored before, during, and after operation and were divided into two groups on the basis of results of monitoring: patients whose total duration of silent ischemia as a percentage of the total duration of perioperative monitoring was 1% or greater (group I, n = 120) and those for whom this value was less than 1% (group II, n = 265). Among patients in group I 13.3% (16 of 120) suffered a perioperative myocardial infarction in contrast to only 1.1% (3 of 265) patients in group II (p less than 0.001). Multivariate logistic regression analysis of preoperative and perioperative characteristics showed that the presence of a total perioperative percent time ischemic 1% or greater and age were the only significant predictors of perioperative myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Silent myocardial ischemia monitoring predicts late as well as perioperative cardiac events in patients undergoing vascular surgery

In a previous study we have shown that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at significantly increased risk for perioperative myocardial infarction. In the present study a group of 385 patients undergoing peripheral vascular surgery was studied long-term as well as short-term to determine whether perioperative monitoring for silent ischemia can identify those patients who are at significantly increased risk of late cardiac death or late cardiac complications as well as those patients at increased risk of perioperative myocardial infarction. All patients were monitored before, during, and after operation and were divided into two groups on the basis of results of monitoring: patients whose total duration of silent ischemia as a percentage of the total duration of perioperative monitoring was 1% or greater (group I, n = 120) and those for whom this value was less than 1% (group II, n = 265). Among patients in group I 13.3% (16 of 120) suffered a perioperative myocardial infarction in contrast to only 1.1% (3 of 265) patients in group II (p < 0.001). Multivariate logistic regression analysis of preoperative and perioperative characteristics showed that the presence of a total perioperative percent time ischemic 1% or greater and age were the only significant predictors of perioperative myocardial infarction. Actuarial freedom at 24 months after operation for group I compared with group II was, respectively, 89.1% versus 98.4% for late myocardial infarction (p < 0.001), 89.5% versus 99.2% for late cardiac death (p < 0.001), and 58.7% versus 69.4% for late cardiac death or late cardiac complication (angina, myocardial infarction, cardiac evaluation, or cardiac revascularization) (p < 0.02). Cox proportional hazards analysis showed that only the occurrence of a total perioperative percent time ischemic 1% or greater and age were significant independent predictors of early or late myocardial infarction and early or late cardiac death as combined end points. These results show that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for late cardiac death or complication as well as perioperative myocardial infarction.