The prognostic value of myocardial viability recognized by low dose dipyridamole echocardiography in patients with chronic ischaemic left ventricular dysfunction.

AIMS: The aim of this study was to assess the prognostic value of myocardial viability recognized as a contractile response to vasodilator stimulation in patients with left ventricular dysfunction in a large scale, prospective, multicentre, observational study. METHODS AND RESULTS: Three hundred and seven patients (mean age 60 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction and severe left ventricular dysfunction (ejection fraction <35%; mean ejection fraction: 28 +/- 7%) were enrolled in the study. Each patient underwent low dose dipyridamole echo (0.28 mg x kg(-1) in 4 min). Myocardial viability was identified as an improvement of >0.20 in the wall motion score index. By selection, all patients were followed up for a median of 36 months. One-hundred and twenty-four were revascularized either by coronary artery bypass grafting (n=83) or coronary angioplasty (n=41). The only end-point analysed was cardiac death. In the revascularized group, cardiac death occurred in one of the 41 patients with and in 16 of the 83 patients without a viable myocardium (2.4% vs 19.3%, P<0.01). Outcome, as estimated by Kaplan-Meier survival, was better for patients with, compared to patients without, a viable myocardium, who underwent coronary revascularization (97.6 vs 77.4%, P=0.01). Using a Cox proportional hazards model, the presence of myocardial viability was shown to exert a protective effect on survival (chi-square 4.6, hazard ratio 0.1, 95% CI 0.01-0.8, P<0.03). The survival rate in medically treated patients was lower than in revascularized patients irrespective of the presence of a viable myocardium (79.7% vs 86.2, P=ns). CONCLUSION: In severe left ventricular ischaemic dysfunction, myocardial viability, as assessed by low dose dipyridamole echo, is associated with improved survival in revascularized patients.

Role of stress echocardiography in risk stratification early after an acute myocardial infarction. EPIC (Echo Persantin International Cooperative) and EDIC (Echo Dobutamine International Cooperative) Study Groups.

Resting and stress echocardiography is a 'one-stop shop', which enables a wide range of information to be collected on resting function, myocardial viability, and induced ischaemia, all of which are useful for prognostic stratification. Large scale, multicentre, prospectively collected data show the prognostic failure of resting function and inducible ischaemia, both independently and combined, which are especially effective in predicting cardiac death. The GISSI data show that the increment of risk as a result of reduction in ventricular function has a hyperbolic trend, with a relatively moderate increase in mortality for ejection fraction values between 50 and 30%, but with marked increases below 30%. The EPIC data show that the 1-year risk of cardiac death is as low as 2% in patients with negative dipyridamole stress echocardiography: it doubles if the test is positive at a high dose, and is almost four times higher if it is positive at a low dose. In the field of prognostic stratification, in the absence of carefully controlled studies, the choice between coronary angiography as the only essential study, or use of a non-invasive test to discriminate access to catheterization currently reflect alternate philosophical approaches rather than scientifically based decisions. In the invasive approach, stress echocardiography offers relief from the vicious circle of chest pain-coronary angiography revascularization. In the non-invasive and physiological approach, stress echo is capable of offering, in one sitting, an insight into the main determinants of survival: function, viability, and ischaemia.

[Evaluation of myocardial viability very early after acute myocardial infarction by ultra-low dose echo-dipyridamole test]. / Valutazione ultraprecoce della vitalità dopo infarto acuto del miocardio mediante test eco-dipiridamolo a dose ultrabassa.

BACKGROUND: After an acute myocardial infarction (AMI), stunned myocardium may cause a reversible left ventricular dysfunction. Dipyridamole echocardiography (0.56 mg*kg-1 over 4' e 0.84 mg*kg-1 over 10') can identify viable myocardium but can also induce ischaemia. AIM OF THE STUDY: To evaluate the usefulness of "Infra-low" dose dipyridamole echocardiography for identification of myocardial viability. METHOD AND RESULTS: Of thirty-four consecutive in-hospital patients, thirty (26 males; mean age 59 +/- 11 years) with AMI separately underwent (40 +/- 12 hours from symptoms onset): 1. a baseline resting echo (BASELINE); 2. a low dose dobutamine (DOB) echotest (5-10 mcg*kg-1*m-1 for 5') (DOB5, DOB10); 3. an "infra-low" dose dipyridamole echotest (0.28 mg*kg-1 over 4') (DIP). A pre-discharge resting echo was performed 7 days after admission (follow-up). No patient developed echocardiographic or electrocardiographic signs of ischaemia after DIP, while 4 patients developed ischaemia after DOB. The systolic blood pressure (112 +/- 18 mmHg) did not change after both DOB and DIP. The heart rate was unchanged after DIP (BASELINE = 73 +/- 18 bpm', DIP = 75 +/- 14 bpm'), while it increased after DOB (BASELINE 69 +/- 11 bpm'; DOB5 = 71 +/- 11 bpm', p = 0.02; DOB10 = 74 +/- 12 bpm', p = 0.001). Wall motion score index (WMSI), in a 16-segment model (from 1 = normal to 4 = diskinetic) (BASELINE = 1.64 +/- 0.3), improved after DIP (1.56 +/- 0.36, p < 0.05 vs BASELINE) and after DOB10 (1.50 +/- 0.36, p < 0.05 vs BASELINE) while did not change after DOB5 (1.59 +/- 0.35, p = n.s.). WMSI decreased at follow-up (1.53 +/- 0.31, p < 0.05 vs BASELINE); DIP and DOB10, but not DOB5, correctly predicted the WMSI decrease observed at follow-up. Results of DOB5, DOB10 and DIP were fully concordant in 118 segments (67%) (kappa = 0.54): 13 (7%) with concordant positivity and 105 (60%) with concordant negativity; 58 (33%) segments showed different results. At follow-up 54 (30%) of the 178 segments with baseline dysfunction, observed in 29 survivors, showed an improvement of grade 1 or more (viable). Two patients did not undergo DOB10; therefore, of the 168 segments with baseline dysfunction, in 27 survivors who underwent all tests, 54 (32%) showed an improvement of grade 1 or more (viable) e 114 (68%) showed no improvement (not viable). Of 25 DOB5 "responders" segments, 11 (44%) showed spontaneous recovery at follow-up (true-positive); of 153 "non responders" segments, 110 (72%) showed no spontaneous recovery at follow-up (true-negative). Of 61 DOB10 "responders" segments, 29 (47%) showed spontaneous recovery at follow-up (true positive); of 107 "non responders" segments, 82 (77%) showed no spontaneous recovery at follow-up (true-negative). Of 36 DIP "responders" segments, 19 (53%) showed spontaneous recovery at follow-up (true positive); of 142 "non responders" segments, 107 (75%) showed no spontaneous recovery at follow-up (true-negative). The sensitivity of DOB5, DIP and DOB10 for predicting short-term spontaneous recovery was 20, 35 and 53% (DOB10 vs DOB5: p < 0.001), respectively; specificity was 88, 86 and 71% (DOB5 vs DOB10: p = 0.002; DIP vs DOB10: p = 0.01); the positive value was 44, 52 and 47% (p = n.s.) and the negative predictive value was 72, 75 and 76% (p = n.s.) while the diagnostic accuracy was 67, 70 and 85% (p = n.s.). CONCLUSIONS: "Infra-low" dose dipyridamole echocardiography appears to be a hemodynamically neutral stress which does not modify either heart rate or blood pressure. It allows to explore selectively the viability of stunned myocardium, without eliciting ischaemia; it shows a good overall concordance with low-dose dobutamine and a low sensitivity but an excellent specificity for predicting spontaneous recovery early after AMI.