Preoperative diagnosis of coronary artery disease in patients with valvular heart disease using technetium-99m isonitrile tomographic imaging together with high-dose dipyridamole and handgrip exercise

Pre-operative computed tomography coronary angiography to detect significant coronary artery disease in patients referred for cardiac valve surgery

OBJECTIVES

We studied the diagnostic performance of 64-slice computed tomography coronary angiography (CTCA) to rule out or detect significant coronary stenosis in patients referred for valve surgery.

BACKGROUND

Invasive conventional coronary angiography (CCA) is recommended in most patients scheduled for valve surgery.

METHODS

During a 6-month period, 145 patients were prospectively identified from a consecutive patient population scheduled for valve surgery. Thirty-five patients were excluded because of CTCA criteria: irregular heart rhythm (n = 26), impaired renal function (n = 5), and known contrast allergy (n = 4). General exclusion criteria were: hospitalization in community hospital (n = 4), no need for CCA (n = 4), previous coronary artery bypass surgery (n = 1), or percutaneous coronary intervention (n = 4). Of the remaining 97 patients, 27 denied written informed consent. Thus, the study population comprised 70 patients (49 male, 21 female; mean age 63 +/- 11 years).

RESULTS

Prevalence of significant coronary artery disease, defined as having at least 1 > or =50% stenosis per patient, was 25.7%. Beta-blockers were administered in 71%, and 64% received lorazepam. The mean heart rate dropped from 72.5 +/- 12.4 to 59.5 +/- 7.5 beats/min. The mean scan time was 12.8 +/- 1.3 s. On a per-patient analysis, the sensitivity, specificity, and positive and negative predictive values were: 100% (18 of 18; 95% confidence interval [CI] 78 to 100), 92% (48 of 52; 95% CI 81 to 98), 82% (18 of 22; 95% CI 59 to 94), and 100% (48 of 48; 95% CI 91 to 100), respectively.

CONCLUSIONS

The diagnostic accuracy of 64-slice CTCA for ruling out the presence of significant coronary stenoses in patients undergoing valve surgery is excellent and allows CTCA implementation as a gatekeeper for invasive CCA in these patients.

High-dose dipyridamole and gated sestamibi SPECT imaging provide diagnostic resting and stress ejection fractions useful for predicting extent of coronary artery disease

A decline in ejection fraction at stress compared with rest images has been associated with increased severity of coronary artery disease (CAD) and suggests a poorer prognosis. Myocardial perfusion imaging (MPI) using high-dose dipyridamole (HDD) has been shown to more accurately detect CAD than either standard dose dipyridamole (SDD) or exercise-induced stress (EST), but has not been looked at to determine its usefulness in detecting changes in stress and rest ejection fractions. To determine the relationship between changes in left ventricular ejection fraction (LVEF) and the severity of CAD, 36 Individuals underwent gated single photon emission computed tomography (SPECT) MPI using HDD. In each case resting and stress LVEFs were determined along with MPI results. Subjects with single-vessel CAD demonstrated an increase in LVEF from 77.8% (sd +/-8.8%) to 85.6% (sd +/-8.4%) resulting in a statistically significant increase in LVEF of 7.8% (p = 0.009). Patients with two-vessel disease showed a smaller increase from 73.2% (sd + 8.3%) to 79.8% (sd + 9.8%) following HDD stress. This increase was statistically (p = 0.008) significant. Patients with triple-vessel CAD showed a reduction in LVEF from 67.4% (sd +/-14.07) to 65.1% (sd +/-16.5%) which represented a decrease in LVEF of 2.7% and approached (p = 0.25) but did not reach statistical significance. Both the resting and stress LVEFs were statistically lower (p<0.05) in patients with triple-vessel CAD. Changes in resting LVEF (REF) and HDD pharmacologically induced stress LVEF (SEF) provide a valuable diagnostic marker as to the number of significantly diseased coronary arteries and can be acquired from gated SPECT sestamibi images.

A tête-à-tête comparison of ejection fraction and regional wall motion abnormalities as measured by echocardiography and gated sestamibi SPECT

Determination of ejection fraction and regional wall motion abnormalities (RWMAs) consistent with stunned, hibernating, or infarcted myocardium can be noninvasively determined by both echocardiography and nuclear cardiac imaging. Prior comparisons between the 2 methods have been limited to Tc 99m pertechnetate or to stress images with attention to RWMAs only. To determine the relationship between results seen with echocardiography and gated single photon emission computed tomography (SPECT) using sestamibi, 26 individuals with varying degrees of coronary artery disease were prospectively studied with both techniques. Five individuals had single-vessel disease, 10 had 2-vessel disease, and 11 had triple-vessel disease. Each individual underwent 2-D, M-mode, and Doppler echocardiography (echo) as well as gated SPECT imaging using rest and stress (high-dose dipyridamole/HDD) sestamibi imaging. The results were statistically different when ejection fractions (EFs) and RWMAs were compared. There were no statistical differences between EFs determined at rest when either echo or nuclear imaging was used. However, patients with EFs <70-80% were overestimated by echo, with echo underestimating EFs >70-80% (p=0.001). There was a high correlation (r=0.76) between resting echocardiographic EFs and SPECT resting gated sestamibi images in patients with single-vessel disease, and a moderate correlation (r=0.68 and r=0.68) in patients with 2- and 3-vessel disease, respectively. Differences in the detection of RWMAs were statistically different for patients with 2-vessel disease (p=0.04) and approached significance in 3-vessel disease (p=0.56) with more RWMA being detected by resting gated SPECT imaging than by echo. Greater differences in RWMAs were seen in patients with 1-, 2-, and 3-vessel disease when resting echo was compared with HDD gated SPECT sestamibi imaging. These differences were statistically greater in 2- (p=0.0027) and 3- (p=0.0003) vessel disease. Differences between stress and resting images are expected in individuals with severe coronary artery disease. Comparison of noninvasive assessment of EFs and RWMAs by gated SPECT sestamibi and echocardiography showed different results when looking at EFs, with echo reporting greater EFs for people with EFs <70-80%. Patients with two and 3-vessel disease were statistically more likely to have RWMAs detected by gated SPECT sestamibi than by echo.

Timing of surgery in aortic stenosis

In adults with valvular stenosis, the importance of prompt aortic valve replacement once symptoms occur is well known. The operative mortality for aortic valve replacement has improved dramatically over the past 4 decades and remains the only effective therapy for severe symptomatic aortic stenosis. Aortic valve replacement in patients with left ventricular dysfunction has a high operative mortality, although those patients who do not undergo surgery at all have an even worse outcome. While issues to consider include the presence or absence of coronary artery disease and expected hemodynamics of the prosthetic valve compared with the native valve, when in doubt, one should err on the side of surgical intervention. Elderly age is not a contraindication to aortic valve replacement for severe symptomatic aortic stenosis, although there is a higher prevalence of comorbid disease and higher operative mortality. Life expectancy is significantly prolonged and quality of life is significantly improved in the elderly who survive surgery. Indications for surgery in asymptomatic patients are controversial. We do not recommend valve replacement in asymptomatic patients at this time due to the known risks of surgery and a prosthetic valve and the lack of evidence for benefit of early surgery. Patients undergoing coronary bypass surgery should be considered for concomitant aortic valve surgery for moderate aortic stenosis that is expected to progress to severe stenosis in less than 5 years.

Dobutamine-atropine stress echocardiography and dipyridamole sestamibi scintigraphy for the detection of coronary artery disease: limitations and concordance

OBJECTIVES

We sought to compare dobutamine-atropine stress echocardiography (DASE) and dipyridamole Technetium 99-m (Tc-99m) sestamibi single photon emission computed tomography (SPECT) scintigraphy (DMIBI) for detecting coronary artery disease (CAD).

BACKGROUND

Both DASE and DMIBI are effective for evaluating patients for CAD, but their concordance and limitations have not been directly compared.

METHODS

To investigate these aims, patients underwent multistage DASE, DMIBI and coronary angiography within three months. Dobutamine-atropine stress echocardiography and stress-rest DMIBI were performed according to standard techniques and analyzed for their accuracy in predicting the extent of CAD. Segments were assigned to vascular territories according to standard models. Angiography was performed using the Judkin's technique.

RESULTS

The 183 patients (mean age: 60 +/- 11 years, including 50 women) consisted of 64 patients with no coronary disease and 61 with single-, 40 with two- and 18 with three-vessel coronary disease. Dobutamine-atropine stress echocardiography and DMIBI were similarly sensitive (87%, 104/119 and 80%, 95/119, respectively) for the detection of CAD, but DASE was more specific (91%, 58/64 vs. 73%, 47/64, p < 0.01). Sensitivity was similar for the detection of CAD in patients with single-vessel disease (84%, 51/61 vs. 74%, 45/61, respectively) and multivessel disease (91%, 53/58 vs. 86%, 50/58, respectively). Multiple wall motion abnormalities and perfusion defects were similarly sensitive for multivessel disease (72%, 42/58 vs. 66%, 38/53, respectively), but, again, DASE was more specific than DMIBI (95%, 119/125 vs. 76%, 95/125, respectively, p < 0.01). Dobutamine-atropine stress echocardiography and DMIBI were moderately concordant for the detection and extent of CAD (Kappa 0.47, p < 0.0001) but were only fairly (Kappa 0.35, p < 0.001) concordant for the type of abnormalities (normal, fixed, ischemia or mixed).

CONCLUSIONS

Dobutamine-atropine stress echocardiography and DMIBI were comparable tests for the detection of CAD. Both were very sensitive for the detection of CAD and moderately sensitive for the extent of disease. The only advantage of DASE was greater specificity, especially for multivessel disease. Dobutamine-atropine stress echocardiography may be advantageous in patients with lower probabilities of CAD.

[Preoperative coronarography in heart valve disease patients. A probability analysis of coronary lesion]

INTRODUCTION AND OBJECTIVES

The indication of preoperative coronary angiography is routinely performed for patients who are going to valve replacement surgery. The need of coronary angiography is based on age, gender and previous angina, but it is not usually based on risk factors. The purpose of this study has been to find markers to predict the probability of coronary lesion in this group of patients.

PATIENTS AND METHODS

We studied retrospectively a population of 541 patients with valvular heart disease who underwent preoperative coronary angiography from 1989 to 1994. Mean age was 61.8 (range 34-82). There were 301 men and 240 women. We analyzed in each patient different variables such as age, gender, previous angina, hypertension, diabetes mellitus, tobacco and familial predisposition. We correlated these variables with the presence of coronary lesion by multivariate analysis.

RESULTS

There were 73 patients with coronary lesion greater than 50%. The prevalence of significant coronary artery disease was 13.4%. Angina was present in 34.6%. The risk of coronary lesion was defined as odds ratio: previous angina 3.3; tobacco 2.6; diabetes 2.2; hypertension 1.8 and age 1.4. The others variables were not predictor of coronary lesion. The probability of coronary lesion in patients without those variables (angina, tobacco, diabetes, hypertension) was 4%. If we analyzed age, the probability of coronary lesion was 3% in patients under 65 years and 6% above 65 years.

CONCLUSIONS

The lack of previous angina and at least the three risk factors described as predictors of coronary lesion (hypertension, tobacco and diabetes) can define a group of patients with a very low prevalence of coronary lesion, especially if they are under 65 years. It can allow us to avoid preoperatory coronary angiography in patients who undergo valve replacement.

Aortic stenosis. Clinical evaluation and optimal timing of surgery

Aortic valve disease is common in the elderly with recent data suggesting that aortic sclerosis and stenosis are the end-stage of an active disease process. Aortic atenosis may be diagnosed at symptom onset (angina, heart failure or syncope) but often the diagnosis is suspected in an asymptomatic patient with a systolic murmur. The diagnosis can be confirmed and disease severity evaluated reliably using Doppler echocardiography. Symptomatic severe aortic stenosis is treated with valve replacement, even in the elderly, due to the extremely poor prognosis without relief of outflow obstruction. Management is controversial when there is coexisting moderate aortic stenosis and left ventricular systolic dysfunction.

Preoperative assessment of coronary artery disease in aortic stenosis: a dipyridamole echocardiographic study

BACKGROUND

The aim of this study was to establish the feasibility, safety, and diagnostic accuracy of the dipyridamole echocardiography test in patients with severe aortic valve stenosis for noninvasive detection of coexisting coronary artery disease.

METHODS

The high-dose dipyridamole echocardiography test was performed in 52 patients with severe aortic stenosis; all patients also underwent coronary angiography, independent of test results, before cardiac operation.

RESULTS

The dipyridamole echocardiography test was completed without major complications. One patient had transient atrial fibrillation that was reversed by aminophylline. Thirty-one patients (60%) had a negative test result; all had normal coronary arteries. Ten of the 21 patients (48%) with a positive test result had coexisting coronary artery disease. The positive predictive value of the dipyridamole echocardiography test for detection of coronary disease in patients with severe aortic stenosis was 48%. The negative predictive value was 100%. The sensitivity was 100% and the specificity was 74%.

CONCLUSIONS

Dipyridamole echocardiography is a safe and feasible tool in patients with severe aortic stenosis eligible for a cardiac operation. A negative test result reliably rules out a significant stenosis, whereas a positive one is much less accurate in predicting coronary artery disease.