Use of stress thallium imaging to stratify cardiac risk in patients undergoing vascular surgery

Pre-operative stress testing in the evaluation of patients undergoing non-cardiac surgery: A systematic review and meta-analysis

Background

Pre-operative stress testing is widely used to evaluate patients for non-cardiac surgeries. However, its value in predicting peri-operative mortality is uncertain. The objective of this study is to assess the type and quality of available evidence in a comprehensive and statistically rigorous evaluation regarding the effectiveness of pre-operative stress testing in reducing 30-day post -operative mortality following non -cardiac surgery.

Methods

The databases of MEDLINE, EMBASE, and CENTRAL databases (from inception to January 27, 2016) were searched for all studies in English. We included studies with pre-operative stress testing prior to 10 different non-cardiac surgery among adults and excluded studies with sample size<15. The data on study characteristics, methodology and outcomes were extracted independently by two observers and checked by two other observers. The primary outcome was 30-day mortality. We performed random effects meta-analysis to estimate relative risk (RR) and 95% confidence intervals (95% CI) in two-group comparison and pooled the rates for stress test alone. Heterogeneity was assessed using I² and methodological quality of studies using Newcastle-Ottawa Quality Assessment Scale. The predefined protocol was registered in PROSPERO #CRD42016049212.

Results

From 1807 abstracts, 79 studies were eligible (297,534 patients): 40 had information on 30-day mortality, of which 6 studies compared stress test versus no stress test. The risk of 30-day mortality was not significant in the comparison of stress testing versus none (RR: 0.79, 95% CI = 0.35–1.80) along with weak evidence for heterogeneity. For the studies that evaluated stress testing without a comparison group, the pooled rates are 1.98% (95% CI = 1.25–2.85) with a high heterogeneity. There was evidence of potential publication bias and small study effects.

Conclusions

Despite substantial interest and research over the past 40 years to predict 30-day mortality risk among patients undergoing non-cardiac surgery, the current body of evidence is insufficient to derive a definitive conclusion as to whether stress testing leads to reduced peri-operative mortality.

Reduced Morbidity and Mortality Following Carotid Endarterectomy: The Value of Preoperative Cardiac Screening

Carotid endarterectomy can be recommended for stroke prophylaxis when performed with low perioperative cardiac morbidity and mortality. In this study the authors evaluate the effectiveness of a cardiac screening protocol using dipyridamole-thallium scintig raphy to identify and treat coexistent coronary artery disease (CAD).

The authors reviewed the medical records of 164 patients undergoing carotid endarterectomy between 1988 and 1993 at the John L. Doyne Hospital and at the Zablocki Veterans Administration Hospital in Milwaukee, Wisconsin. Results of the preop erative cardiac evaluations and the incidence of perioperative cardiac events were recorded.

Forty patients without any evidence of cardiac disease by history or electrocardio gram went on to surgery without further screening. Eight patients underwent coronary catheterization without dipyridamole-thallium scan, owing to the severity of their cardiac symptoms. A cardiology consultation and dipyridamole-thallium scan were obtained preoperatively in the remaining 116 patients with a history of CAD. Of these 116 patients, 62 (53.4%) were diagnosed as normal. Thirty-five (30%) scans demonstrated reversible reperfusion defects, leading to preoperative coronary angiography in 17 patients and to cardiac revascularizations in 8. Nineteen (16.4%) scans demonstrated a fixed perfusion defect; 3 of these patients underwent coronary catheterization, leading to cardiac revas- cularization in 1 patient. Of 2 patients (1.7%) who suffered a postoperative myocardial infarction, 1 patient had a fixed perfusion defect and 1 was found to have a two-vessel disease on coronary catheterization. There were no perioperative deaths. In the follow- up period (15.9 months; range one to sixty), no cardiac deaths occurred.

With this treatment algorithm using selective dipyridamole-thallium scan evaluation, perioperative and long-term cardiac morbidity and mortality can be minimized.

Women have increased risk of perioperative myocardial infarction and higher long-term mortality rates after lower extremity arterial bypass grafting

PURPOSE

The purpose of this study was to determine the effect of gender on the immediate and long-term postoperative morbidity, mortality, and patency rates for infrainguinal autogenous vein bypass grafts.

METHODS

Data were abstracted for consecutive patients who were followed in a prospective surveillance protocol after undergoing infrainguinal autogenous vein bypass grafting during the years 1988 to 1994. There were 165 grafts constructed in 148 patients (101 in 87 men, and 64 in 61 women). Gender differences were analyzed with Student t test or chi2 test for risk factors, indications for reconstruction, and complications. The patency rates and the long-term survival rates were compared by means of life-table analysis. Eagle criteria and long-term survival rates were compared with multivariate analysis.

RESULTS

The mean follow-up period was 36 months (39 months for men, and 32 months for women), with a range of 6 to 123 months for the total follow-up period. The two groups did not differ in age at the time of operation (66.6 +/- 1.2 years for men, and 66.7 +/- 1.5 years for women) or in history of diabetes (48% for men, and 56% for women). The risks were similar for hypertension (48% for men vs 45% women), preoperative myocardial infarction (23% for men vs 26% for women), and previous coronary artery bypass grafting (9% for men vs 8% for women). The thallium stress scintigraphy results showed a diagnosis of proportionately more preoperative defects in men (reversible, 34% vs 18%, P <.05; overall, 75% vs 43%, P <.05). The 30-day limb loss rates (0.9% for men, and 0% for women) and mortality rates (2.2% for men, and 5% for women) were similar. Women had statistically more perioperative myocardial infarctions than did men (6 of 61, 9.8% vs 2 of 101, 2%; P <.05), as was documented with electrocardiography and cardiac isoenzymes. Two of these women died within a 30-day postoperative period. The 3-year primary patency rate was 85% for the men and 88% for the women, and the primary assisted patency rate was 97% for the men and 97% for the women. The secondary patency rate was 98% for the men and 97% for the women. The limb salvage rate was slightly higher for the men than for the women (93% vs 87%), although this was not statistically significant. The 5-year survival rate for women was statistically less than for men, with life-table analysis (58% for men vs 42% for women; P <.05).

CONCLUSION

After distal bypass grafting, men and women have similar rates of patency and limb salvage, but women have a higher incidence rate of perioperative myocardial infarction and a decreased 5-year survival rate. These data suggest that women have unrecognized cardiac disease that affects them adversely in the perioperative period and the long term when compared with men who undergo the same operation.

The limits of generalized cardiac screening tests for predicting cardiac complications after infrainguinal arterial reconstruction

We examined the relative efficacies of different cardiac screening strategies for infrainguinal arterial bypass. The outcomes of 205 elective leg bypass procedures over a 10-year period, including myocardial infarction (MI), total cardiac complications, and mortality were tallied. Clinical risk factors popularized by Goldman and Eagle, and the results of dipyridamole thallium myocardial imaging (DThal) were recorded. The overall mortality rate was 3.4%, with a 3.4% incidence of MI and a 5.4% total cardiac complication rate. Both abnormal DThal (p = 0.011) and Goldman class II-IV (p = 0.030) were significant predictors of MI and cardiac death, but both suffered from poor specificity and positive predictive value. Because logistic regression analysis identified a correlation between angina, CHF, and an abnormal DThal, a customized screening strategy was developed to include the presence of angina, CHF and an abnormal DThal. Eighty-eight percent of patients suffering MI or death met these criteria, while only 11% of the complication-free group did. This screening strategy provided a superior sensitivity of 88%, specificity of 89%, positive predictive value of 25%, and 99% negative predictive value. A customized screening strategy (angina, CHF, abnormal DThal), developed from a 10-year experience with a single patient group, provided better predictive accuracy than any generalized screening formula.

Does routine stress-thallium cardiac scanning reduce postoperative cardiac complications?

OBJECTIVE

Prophylactic cardiac revascularization in patients with ischemic myocardium could reduce postoperative cardiac complications after aortic reconstruction. However, the effectiveness of this approach has not been documented.

SUMMARY BACKGROUND DATA

Stress-thallium scanning can identify patients with ischemic myocardium. Morbidity and mortality after aortic reconstruction appears to be largely caused by co-existent coronary artery disease, and patients who have had recent cardiac revascularization have few postoperative cardiac complications.

METHODS

Preoperative stress-thallium scanning was evaluated prospectively in 146 patients undergoing aortic reconstruction. Patients with positive studies underwent coronary arteriography and cardiac revascularization, when appropriate. Postoperative cardiac complications and long-term survival in these patients were compared with results from 172 similar patients undergoing aortic reconstruction without stress-thallium scanning. Results also were analyzed to determine predictors of postoperative cardiac events.

RESULTS

Forty-one per cent of patients undergoing stress-thallium testing underwent coronary arteriography, and 11.6% had cardiac revascularization. In contrast, 14.7% of patients treated without stress-thallium testing had coronary arteriography, and 4.1% had revascularization (p < 0.01). Despite this, cardiac mortality, serious cardiac complications, and long-term cardiac mortality were similar in both groups. Only advanced age and intraoperative complications (but not a positive stress-thallium test) predicted postoperative cardiac events.

CONCLUSIONS

Preoperative stress-thallium testing confirmed a high incidence of significant coronary artery disease in patients undergoing aortic reconstruction, but prophylactic cardiac intervention does not reduce operative or long-term mortality. Thus, the risk and expense of routine stress-thallium testing and subsequent cardiac revascularization cannot be justified.