Reduced microvascular and myocardial damage in patients with acute myocardial infarction and preinfarction angina.

BACKGROUND: After acute myocardial infarction, the presence of ischemic preconditioning as a result of preinfarction angina has a protective role, limiting necrosis extent and guaranteeing greater myocardial functional recovery. The relationship between preinfarction angina, microvascular reflow, and myocardial function is poorly known. We hypothesized that after acute myocardial infarction patients with preinfarction angina have both microvascular integrity and myocardial function preservation. METHODS AND RESULTS: In 51 patients with a first acute myocardial infarction, we noninvasively assessed microvascular perfusion and coronary flow reserve with intravenous myocardial contrast echocardiography and investigated myocardial contractile recovery with low-dose dobutamine and 90-day follow-up echocardiography. Typical angina was present in 25 patients and absent in 26 patients during the 7 days preceding the myocardial infarction. Compared with those patients without preinfarction angina, patients with preinfarction angina showed a greater microvascular reflow extent and coronary flow reserve (respectively, 25.2% +/- 22.8% vs 48.3% +/- 23.3%, P <.05, and 3.44 +/- 0.75 vs 1.95 +/- 0.67, P <.0001), a better regional myocardial function, as expressed with wall motion score index in the risk area at dobutamine (1.67 +/- 0.61 vs 2.10 +/- 0.43, P <.005) and at follow-up (1.72 +/- 0.56 vs 2.22 +/- 0.40, P <.0001) echocardiogram, despite being similar in the first echocardiogram (2.60 +/- 0.28 vs 2.63 +/- 0.28, P = not significant), and significantly less pronounced left ventricular dilation at follow-up. CONCLUSION: Presence of preinfarction angina, because of the preconditioning effect, reduces myocardial damage and favors myocardial viability, limiting left ventricular remodeling. This beneficial effect seems to be at least partly mediated by the more preserved microvascular integrity and functional vasodilation after acute myocardial infarction.

Post-infarction microvascular integrity predicts myocardial viability and left ventricular remodeling after primary coronary angioplasty. A study performed with intravenous myocardial contrast echocardiography.

BACKGROUND: After acute myocardial infarction the preservation of the microvasculature is a pre-requisite for myocardial viability, limited ventricular remodeling and a better prognosis. Intracoronary myocardial contrast echocardiography after acute myocardial infarction can detect the extent of microvascular damage. We hypothesized that intravenous myocardial contrast echocardiography after acute myocardial infarction treated with primary coronary angioplasty can predict the contractile reserve at low-dose dobutamine echocardiography, myocardial functional recovery and left ventricular remodeling. METHODS: We studied 37 patients with a first acute myocardial infarction and submitted to primary coronary angioplasty. All patients underwent echocardiography on the day they had the acute myocardial infarction, intravenous myocardial contrast echocardiography with power Doppler imaging 2.9 +/- 0.5 days later and dobutamine echocardiography 3.7 +/- 1.2 days after the acute myocardial infarction. In all cases, an echocardiography was performed at 3 months of follow-up. RESULTS: At intravenous myocardial contrast echocardiography, 25 patients showed contrast enhancement (reflow) and 12 a sizeable contrast defect (no-reflow). Reflow patients were found to have a regional wall motion score index similar to that of the no-reflow patients on the first day echocardiogram (2.6 +/- 0.4 vs 2.8 +/- 0.2, p = NS), but this parameter was smaller than that of the no-reflow patients at dobutamine echocardiography (1.5 +/- 0.4 vs 2.6 +/- 0.2, p < 0.0001) and at follow-up echocardiography (1.5 +/- 0.5 vs 2.6 +/- 0.2, p < 0.0001). The sensitivity and specificity of intravenous myocardial contrast echocardiography in identifying myocardial functional recovery at follow-up were 80 and 64%, while the sensitivity and specificity of dobutamine echocardiography were 85 and 76%. In no-reflow patients the left ventricular volumes increased from the acute to the chronic phase (end-diastolic volume from 71.9 +/- 14.1 to 100.9 +/- 40.6 ml/m2, p < 0.0001, +28%; end-systolic volume from 43.1 +/- 10.1 to 61.1 +/- 30.1 ml/m2, p < 0.0001, +29%), while they remained constant in reflow patients (end-diastolic volume from 71.8 +/- 20.1 to 71.1 +/- 15.4 ml/m2, p = NS, -1%; and end-systolic volume from 39.9 +/- 11.9 to 36.3 +/- 12.8 ml/m2, p = NS, -8%). CONCLUSIONS: Intravenous myocardial contrast echocardiography is capable of identifying patients with a post-infarction contractile reserve and myocardial functional recovery; it also allows the early identification of patients prone to late left ventricular dilation, thus permitting a more aggressive diagnostic and therapeutic strategy.

[Heterozonal electrocardiographic changes in ST-elevation myocardial infarction]. / Coinvolgimento del miocardio remoto nel corso di infarto miocardico acuto con sopralivellamento del tratto ST: le alterazioni ischemiche eterozonali all'elettrocardiogramma.

BACKGROUND: It has been observed that in patients with ST-elevation myocardial infarction (STEMI) the presence of ST-segment depression (ST) in heterozonal electrocardiographic leads (remote STI) worsens the patient's prognosis. The aim of this study was to observe in an unselected population with a first STEMI the incidence of remote STI and the risk factors related to this condition. METHODS: We evaluated retrospectively 350 patients with a first STEMI; we excluded from our analysis 139 patients because no data about their coronary anatomy was available. ST-segment depression in the heterozonal myocardium was considered significant if > 0.1 mV at 60 ms from the J point, in at least two electrocardiographic leads. RESULTS: Patients were classified according to the presence (group 1, 117 patients) or absence (group II, 94 patients) of remote ST. The two groups did not differ for age, sex and coronary anatomy. In group I we found more heterozonal wall motion abnormalities than group II (32 vs. 18%, p = 0.018). In this group there was a higher incidence of smokers (56 vs. 33%, p = 0.025) and less patients were treated with statins when the STEMI occurred (6 vs. 14%, p = 0.047). Patients with remote ST had higher total cholesterol (214.6 +/- 48.9 vs. 192.3 +/- 29.8 mg/dl, p < 0.001) and low-density lipoprotein cholesterol (138.7 +/- 40.7 vs. 123.2 +/- 22.9 mg/dl, p < 0.0001) levels. Conclusions. In patients with STEMI the presence of remote ST is rather frequent, and seems to indicate a real heterozonal ischemia, independently of an epicardial coronary stenosis of the non-infarct-related artery. Remote ST. is associated with a higher incidence of risk factors related to microcirculatory dysfunction, such as cigarette smoking, a worse lipid profile and less protective factors, such as the use of statins prior to acute myocardial infarction.