Usefulness of transesophageal atrial pacing combined with two-dimensional echocardiography (echo-pacing) in predicting the presence and site of residual jeopardized myocardium after uncomplicated acute myocardial infarction

Ischemia induced by transesophageal atrial pacing stress echocardiography predicts long-term mortality

OBJECTIVES

It was the aim of this study to investigate the long-term value of transesophageal atrial pacing in predicting death in patients with known or suspected coronary artery disease.

BACKGROUND

Exercise, dobutamine and dipyridamole stress echocardiography are all effective in predicting cardiac death. Transesophageal atrial pacing stress echocardiography (TAPSE) is a safe alternative to pharmacologic tests, but no information is available on prognosis with TAPSE.

METHODS

One thousand and ten TAPSE were performed in 975 consecutive patients. TAPSE was feasible in 970 tests (96%); after exclusion of the 35 patients with more than 1 TAPSE and those 42 lost at follow-up (mean 4.5 +/- 3.7 years, median 6 years), the final population consisted of 857 patients (675 males, 58 +/- 9 years old). The Cox model was used to analyze the association of clinical, resting and TAPSE variables with cardiac death.

RESULTS

TAPSE was abnormal in 281 (32%) patients. There were 46 cardiac-related deaths (5%), 25 among the 281 patients with an abnormal test (8.9%) and 21 among the 576 patients with a normal test (3.6%). The predictors of cardiac death were age, previous revascularization, resting wall motion score index and its variation during TAPSE. Abnormal TAPSE significantly increases the value of models predicting cardiac death. Moreover, cardiac mortality increased progressively with the extent of the induced ischemia.

CONCLUSIONS

TAPSE is a useful tool in predicting death in patients with known or suspected coronary artery disease and might be considered an alternative to pharmacologic stressors.

Systematic overview and clinical applications of pacing atrial stress echocardiography

Pacing atrial stress echocardiography (PASE) has been studied over the past 3 decades for the evaluation of myocardial ischemia. Published studies suggest that PASE may be used as an alternative to exercise or pharmacologic stress imaging. The recent introduction of improved pacing electrodes, together with use of accelerated and shortened pacing protocols and improvements in transthoracic echocardiographic imaging techniques, makes PASE an appealing stress imaging method. A critical analysis of the diagnostic accuracy of PASE shows equivalence with other imaging stress modalities. PASE has been found to be highly feasible and accurate technique that may expedite the diagnosis and risk stratification of patients with coronary artery disease. This review addresses the history, hemodynamics, protocols, accuracy, clinical utility, and cost-effectiveness of PASE as well as elucidating its place among other stress modalities.

Comparison of the long-term survival benefits associated with revascularization or medical therapy in patients with known coronary artery disease undergoing transesophageal atrial pacing stress echocardiography

Although the utility of stress echocardiography for the diagnosis and prognostic evaluation of patients with suspected coronary artery disease (CAD) has been widely reported, few studies have evaluated the role of revascularization in relation to the presence of inducible ischemia during stress in patients with known CAD. The study population consisted of 295 consecutive patients who underwent transesophageal atrial pacing stress echocardiography (TAPSE) in the echocardiographic laboratory of our division between January 1988 and September 1997, in whom coronary angiography was performed within 10 days of the test. Patients were then assigned to revascularization or medical treatment according to the treatment given within 60 days of TAPSE. Cardiac-related deaths were higher in medically treated (19 of 135) than in revascularized (8 of 160) patients (p = 0.03). Parameters measured with TAPSE, i.e., positivity of the test, change in wall motion score index (DeltaWMSI and peak WMSI) were significantly related to mortality in medically treated patients but not in revascularized patients. At multivariate analysis, DeltaWMSI remained the most powerful predictor of cardiac death in medically treated patients (p = 0.005). Mortality progressively increased with increments in extent of inducible ischemia among medically treated patients (5 of 71 patients in DeltaWMSI 0, 3 of 27 in DeltaWMSI 0 to 25, 11 of 37 patients in DeltaWMSI >25) but not among revascularized patients (3 of 58 patients in DeltaWMSI 0, 2 of 51 in DeltaWMSI 0 to 25, 3 of 51 patients in DeltaWMSI >25). The survival curve in medically treated patients with ischemia in a remote zone (24 patients, 8 deaths) was worse than in other groups of medically treated patients (41 patients, 6 deaths). In conclusion, in patients with known CAD, the presence and extent of ischemia as evaluated with TAPSE worsens survival, if revascularization is not performed. In patients without ischemia at TAPSE, revascularization or medical therapy are equally effective.

Feasibility and safety of transeophageal atrial pacing stress echocardiography in patients with known or suspected coronary artery disease

To investigate the feasibility and safety of the transesophageal atrial pacing stress test combined with echocardiography (TAPSE) 1,727 TAPSE tests were performed on 1,641 patients consecutively referred to our echocardiographic laboratory for nonexercise stress testing (1,319 men; mean age 60 +/- 9 years; 34% of whom were outpatients). Wall motion abnormalities were present at baseline echocardiography in 975 cases (56%). TAPSE was feasible in 1,648 cases (95.4%). It was not feasible in 79 patients due to failure of positioning the transnasal catheter (n=11), the patient's intolerance of esophageal stimulation (n=24), failure to obtain any or stable atrial capture (n=36), or because the echocardiogram could not be evaluated at the peak of the test (n=8). TAPSE was diagnostic in 1,584 cases (96% of the feasible tests, 92% of all attempts). TAPSE was nondiagnostic in 64 cases (4% of the feasible tests) due to second-degree atrioventricular type I block resistance to atropine administration with failure to achieve 85% of the age-predicted maximum heart rate (n=59) or due to side effects, such as arrhythmias (n=3) or hypertension (n=2), which required premature interruption of the test. There were no major complications (death, myocardial infarction, or life-threatening arrhythmias). There were 28 instances of minor complications that comprised transient arrhythmias, including atrial fibrillation (n=8), paroxysmal supraventricular tachycardia (n=6), automatic atrial tachycardia (n=1), sinus arrest (n=1), atrioventricular junctional rhythm (n=2), ectopic atrial rhythm (n=2), nonsustained ventricular tachycardia (maximum 6 beats, n=3), hypotension (n=1), and hypertension (n=4) leading to interruption of the test. Only 5 complications hampered a diagnostic result, whereas 18 occurred during or after a positive test and 5 during a negative, but diagnostic, test. Thus, TAPSE is a highly feasible and very safe stress test. It gives high percentage of diagnostic tests and may represent a valid alternative to pharmacologic stressors.

Myocardial viability independently influences left ventricular diastolic function in the early phase after acute myocardial infarction

BACKGROUND

After acute myocardial infarction, a broad range of left ventricular (LV) end-diastolic pressure (LVEDP) is expected because of chamber remodeling. However, intrinsic characteristics of the infarcted tissue (necrosis or viability) may also play a role. We aimed to evaluate whether myocardial viability (Mviab) has an influence on LVEDP.

METHODS

One hundred twenty-three consecutive patients with acute myocardial infarction underwent low-dose dobutamine echocardiography (5-10 microg/kg/min) to assess Mviab. Mviab was quantitatively evaluated by the variation of Delta wall motion score index. Patients underwent left heart catheterization with recording of LVEDP and a complete echocardiographic examination with measurement of LV volumes, ejection fraction, and mass.

RESULTS

The overall population (81% male; mean age 58 +/- 10 years) was divided into 2 groups according to the presence (group 1; 66 patients) or absence (group 2; 57 patients) of Mviab. LVEDP was higher in patients without Mviab (16 +/- 8 vs 20 +/- 7 mm Hg; P =.02). The multivariate analysis showed that Delta wall motion score index correlated with LVEDP (P =.01) independent of wall motion score index and LV end-systolic volume.

CONCLUSIONS

After acute myocardial infarction, LVEDP shows wide variability and is independently associated with Mviab.

Relationship between mitral regurgitation and myocardial viability after acute myocardial infarction: their impact on prognosis

Mitral regurgitation (MR) after acute myocardial infarction (AMI) is an important prognostic factor. Although its mechanisms are still debated, ventricular remodeling probably plays an important role. Because myocardial viability (MV) in the infarct zone reduces infarct expansion and ventricular remodeling, it is also possible that its presence counteracts the development of mitral regurgitation in infarcted patients. To evaluate this issue 191 patients with uncomplicated AMI, wall motion abnormalities (akinesis) and semiquantitative evaluation of MR were retrospectively selected from those consecutively examined at our echo-laboratory to evaluate MV using low-dose dobutamine echocardiography (DbE). Follow-up evaluation was performed at 30+/-13 months. Seventy-nine patients had no MR; 86 patients had grade 1 MR, 11 patients had grade 2 MR, nine patients had grade 3 MR, and six patients had grade 4 MR. Patients with significant MR (>grade 1) were older (63+/-7 vs. 59+/-10 years, P=0.03), had lower reduction of RWMSI (DeltaRWMSI) during DbE (0.08+/-0.11 vs. 0.22+/-0.28, P=0.01), more stenotic vessels at coronary angiography (2.35+/-0.93 vs. 1.67+/-1.12, P=0.01), and more frequently had anterior-inferior AMI (P<0.0001); they also had a non-significant tendency to higher RWMSI (2.04+/-0.38 vs. 1.92+/-0.28, P=0.06). In a multivariate regression analysis, DeltaRWMSI proved to be significantly related to the grade of MR (P=0.02). Eighteen patients died during follow-up. Death was more frequent in patients with MR (10/165 vs. 8/26, P=0.0003). At multivariate stepwise Cox regression analysis both the extent of ventricular dysfunction and the presence of MR were significantly related to mortality (P<0.0001 and P=0.01, respectively); DeltaRWMSI showed a non-significant tendency to influence mortality (P=0.09). When MR was excluded from the multivariate analysis, DeltaRWMSI remained significantly related to mortality (P=0.05). In conclusion our study suggests that the presence of MV in infarcted patients influences the development of MR. This reduction of MR may be one of the mechanisms by which MV affects mortality after AMI and should be considered in all studies that evaluate MV after myocardial infarction.

Use of stress echocardiography for risk assessment of patients after myocardial infarction

The main predictors of outcome after infarction (exercise capacity, ejection fraction, and extent of jeopardized myocardium) can all be identified using stress echocardiography. This review addresses the place of stress echocardiography in postinfarct risk evaluation, relative to clinical evaluation, and other technologies. The test is accurate for identification of multivessel disease and for predicting outcomes, is versatile, and can be used early after infarction.

Comparison of left ventricular function and volumes during transesophageal atrial pacing combined with two-dimensional echocardiography in patients with syndrome X, atherosclerotic coronary artery disease, and normal subjects

Nine patients with syndrome X were compared with 2 groups of patients known to have coronary artery disease (CAD) (8 patients who developed regional wall motion abnormalities [group ECHO+] and 6 patients who showed only ST depression at echo-pacing [group ECG+]) and with 6 healthy volunteer control subjects. Left ventricular function at rest was normal in all patients. End-diastolic and end-systolic volumes (ml/m2) and ejection fraction were calculated at baseline and at peak of echo-pacing using a Simpson's biplane method. No regional wall motion abnormalities were observed during the echo-pacing in patients with syndrome X or in the volunteers. End-diastolic volume decreased in patients with syndrome X, in the volunteers (from 47 +/- 11 to 30 +/- 12 and from 72 +/- 7 to 38 +/- 6, respectively, p <0.01 for both), and in ECG+ patients (from 48 +/- 10 to 33 +/- 6, p <0.05), whereas it did not change in ECHO+ patients. End-systolic volume decreased in patients with syndrome X and in the volunteers (from 17 +/- 5 to 11 +/- 4 and from 28 +/- 6 to 16 +/- 4, respectively, p <0.01 for both), whereas it did not change or else slightly increased in patients with CAD (from 18 +/- 10 to 16 +/- 5 for ECG+ patients and from 19 +/- 5 to 24 +/- 9 for ECHO+ patients, p = NS for both), regardless of whether regional wall motion abnormalities appeared. Ejection fraction decreased in ECG+ and ECHO+ patients (from 64 +/- 12 to 52 +/- 11 and from 62 +/- 9 to 44 +/- 13, respectively, p <0.01 for both), whereas it did not change in patients with syndrome X and in the volunteers (from 64 +/- 8 to 61 +/- 8 and from 61 +/- 7 to 58 +/- 7, respectively, p = NS for both). During echo-pacing in syndrome X patients no regional wall motion was detected. Left ventricular volumes and ejection fraction showed the same patterns of variation in these patients as they did in the healthy control subjects, in contrast with those patients with CAD, whether or not regional wall motion abnormalities appeared in the latter.

[II. Role of Doppler echocardiography in the management of chronic ischemic cardiopathy]

Doppler echocardiography is a simple, fast and non-invasive method to identify abnormal regional and global left ventricular function. One could consider this method the best application for this end within the techniques of imaging. This chapter reviews the role of Doppler echocardiography in the management of chronic coronary artery disease, as well as for studying the global and regional function at rest, as in the applications derived from their use during stress testing. Frequent techniques of stress echocardiography for the diagnosis of ischemic heart disease, their utility in the study of myocardial viability, and the establishment of recommendations for their use in clinical practice are analyzed.

Comparison of the diagnostic potential of four echocardiographic stress tests shortly after acute myocardial infarction: submaximal exercise, transesophageal atrial pacing, dipyridamole, and dobutamine-atropine

This study assessed and compared the diagnostic potential of submaximal exercise, transesophageal atrial pacing, dipyridamole, and dobutamine-atropine stress echocardiography tests shortly after acute myocardial infarction. In 121 study patients, 325 digital echocardiographic stress tests were attempted 10 to 11 days after acute myocardial infarction: 83 submaximal exercise tests, 121 high-dose dipyridamole echocardiography tests (DET), 69 transesophageal atrial pacing tests (< 150 beats/min), and 52 dobutamine tests, starting at 10 microgram/kg per minute, increasing stepwise to 40 microgram kg/min, and coadministering atropine in 12 patients (dobutamine-atropine stress echocardiography [DASE]). Results were correlated to a coronary artery diameter stenosis > or = 50% as determined by quantitative angiography. Feasibility to perform submaximal exercise echocardiography, atrial pacing echocardiography, DET, and DASE was 89%, 52%, 98%, and 88%, respectively. Atrial pacing was not tolerated by 18 patients and refused by 6 (9%). Severe but not life-threatening side effects were hypotension in DET (2%) and tachyarrhythmias in DASE (6%). Test positivity in multivessel disease with submaximal exercise, DET, and DASE was 55%, 93%, and 90%, respectively, and in 1-vessel disease 47%, 65%, 71%, and for atrial pacing, 82%, respectively. We conclude that submaximal exercise has limited sensitivity and atrial pacing limited feasibility. The pharmacologic stressors provide a useful, safe diagnostic approach: DET with slightly lower sensitivity in 1-vessel disease and DASE with insignificantly less feasibility.