ABSTRACT
BACKGROUND: Successful reperfusion therapy in patients with acute myocardial infarction (AMI) improves survival. Indeed, after AMI myocardial dysfunction may be reversible (hibernating or stunned myocardium). Low-dose dobutamine stress echocardiography (LDDSE) provides us with the possibility of evaluating viable myocardial segments, while myocardial contrast echocardiography (MCE) allows the study of the microcirculation in the same myocardial areas. The aim of our study was to compare LDDSE and MCE, in the prediction of the recovery of segments in patients with AMI who were submitted to primary coronary angioplasty (PTCA). METHODS: We studied 14 patients with AMI. Both LDDSE and MCE with Levovist were performed after primary PTCA. The viability gold standard was a recovery of contractility detected at echocardiography 2 months later. RESULTS: For LDDSE, the sensitivity was 91%, the specificity 71% and the positive and negative predictive values were 93 and 64% respectively. For MCE, the sensitivity was 94%, the specificity 44%, the positive predictive value 89%, and the negative predictive value 59%. Two tests agreed in 81% of the cases. Stress echocardiography and contrast echocardiography agreed in 81% of cases. CONCLUSIONS: LDDSE has a very good positive accuracy, it has an acceptable negative predictive value and is relatively cheap. On the other hand, MCE has a good positive accuracy, but a low negative accuracy and carries a high cost. The integration of these two tests, which are too expensive in clinical practice, could improve our comprehension of the post-PTCA pathophysiology.
Subject(s)
Angioplasty, Balloon, Coronary/methods , Echocardiography, Doppler/methods , Echocardiography, Stress/methods , Myocardial Contraction/physiology , Myocardial Infarction/diagnostic imaging , Myocardial Infarction/therapy , Aged , Angioplasty, Balloon, Coronary/adverse effects , Contrast Media , Coronary Circulation/physiology , Female , Humans , Male , Middle Aged , Monitoring, Physiologic/methods , Myocardial Infarction/mortality , Prospective Studies , Risk Assessment , Sampling Studies , Sensitivity and Specificity , Severity of Illness Index , Stents , Survival Rate , Treatment Outcome , Vascular PatencyABSTRACT
BACKGROUND: Several studies showed that there is a state of platelet hyperactivaction in patients with coronary syndrome: the aim of this study is to investigate if the platelet nitric oxide-cyclicGMP (NO-cGMP) pathway, that regulates platelet aggregation is altered in patients with unstable angina (UA) and acute myocardial infarction (AMI). METHODS AND RESULTS: Population included 11 patients with UA, 12 patients with AMI and 23 controls. Platelet cGMP was measured by a radioimmunoassay kit, under basal conditions and after stimulation with sodium nitroprusside (SNP), which maximally stimulates soluble guanylate cyclase (sGC), used as an indirect measurement of active sGC. Basal platelet cGMP values were significantly (P<0.001) higher in patients with UA and AMI than in controls (UA, 1089 +/- 412 pmol/10(10) platelets; AMI, 1071 +/- 507 pmol/10(10) platelets; controls, 492 +/- 201 pmol/10(10) platelets). The final cGMP level reached after SNP stimulation was significantly more elevated in UA, compared with both AMI (P<0.05) and controls (P<0.02) (UA, 4428 +/- 2723 pmol/10(10) platelets; AMI, 2728 +/- 655 pmol/10(10) platelets; controls, 2772 +/- 1031 pmol/10(10) platelets); on the contrary no significant difference between AMI and controls was observed. CONCLUSIONS: Basal platelet cGMP is significantly higher in both UA and AMI groups. This observation suggests that: (1) platelet-derived NO synthesis may be enhanced inUA and AMI, due to increase of intraplatelet calcium level and of platelet cNOS activation; (2) platelets from UA and AMI patients are continuously stimulated by the high-level NO production due to increased iNOS expression. As far as SNP-dependent cGMP production is concerned, UA and AMI behave as two separate conditions. SNP-stimulated activity in UA is higher than in controls, while a loss of functional sGC is observed in AMI.
