Silent myocardial ischemia after myocardial infarction: severity of coronary artery disease, impact on left ventricular systolic and diastolic functions and prognosis

Impaired tissue Doppler diastolic function in patients with coronary artery disease: relationship to endothelial damage/dysfunction and platelet activation

BACKGROUND

Pulsed tissue Doppler imaging (TDI) allows direct measurement of systolic and diastolic function of the left ventricle. In patients with coronary artery disease (CAD), myocardial ischemia-related impaired diastolic function may be linked to systemic endothelial damage/dysfunction and increased thrombogenesis. We hypothesized relationships between TDI-defined diastolic dysfunction and plasma von Willebrand factor (vWf, marking endothelial damage/dysfunction), soluble P-selectin (sP-sel, reflecting platelet activation), fibrin D dimer (an index of fibrin turnover and thrombogenesis), fibrinogen, and plasma viscosity (PV) in CAD.

METHODS

Conventional 2-dimensional Doppler echocardiography and TDI were performed in 75 stable CAD patients (55 men, 59 +/- 11 years) and 40 age- and sex-matched healthy controls. Peak systolic (Sm), peak early (Em), and late (Am) diastolic mitral annular velocities measured at 4 sites (septal, lateral, inferior, and anterior) were averaged as global systolic and diastolic left ventricular function, respectively. The mean TDI velocities were dichotomized into low and high (below/above median) groups. Plasma vWf, sP-sel, D dimer (enzyme-linked immunosorbent assay), fibrinogen (modified Clauss), and PV levels were measured.

RESULTS

CAD patients had significantly lower Sm, Em, Em/Am ratio, and a higher ratio of early transmitral flow E-velocity over Em (E/Em) when compared with controls (all P < .05). On multivariate analysis, adjusted for age, ejection fraction, and clinical variables, the differences in the group means of vWf, sP-sel, and fibrinogen remained significantly different between the low and high TDI indexes. D-dimer levels were unrelated to any TDI indexes. None of the transmitral flow indexes were independently related to the research indexes.

CONCLUSIONS

In patients with CAD, diastolic dysfunction was closely associated with increased platelet activation and endothelial damage/dysfunction independent of systolic function. TDI-derived indexes are more sensitively related to plasma hemostatic markers than transmitral indexes in middle-aged patients with CAD.

Determinants of left ventricular systolic function after acute myocardial infarction: the role of residual myocardial ischaemia

BACKGROUND

Left ventricular systolic function (LVSF) is one of the major determinants of survival after acute myocardial infarction (AMI). Some factors such as the infarct size and localization, and the patency of the infarct-related artery are known determinants of LVSF. However, the long-term effect of myocardial ischaemia on LVSF has been poorly studied in clinical settings.

OBJECTIVES

To assess the acute and long-term effects of myocardial ischaemia on LVSF in patients recovering from an AMI.

METHODS

A cohort of 74 patients recovering from AMI was studied. Myocardial ischaemia was detected by means of ambulatory electrocardiogram (ECG) monitoring at recruitment (4+/-2 days after AMI), exercise ECG test and stress echocardiography at discharge (7+/-4 days after AMI). LVSF was studied by means of two-dimensional echocardiography at recruitment, at discharge, and at 1, 3, 6 and 12 months after AMI.

RESULTS

Patients with myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had worse LVSF at recruitment than those without ischaemia. The presence of myocardial ischaemia on ambulatory ECG monitoring was an independent determinant of LVSF at recruitment together with infarct localization and size (assessed by creatine kinase MB isoenzyme (CK-MB) levels). Patients with signs of myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had a progressive left ventricular dysfunction compared with those without ischaemia.

CONCLUSIONS

Residual ischaemia is an independent determinant of LVSF after AMI and its presence implied a progressive worsening of the LVSF. Because left ventricular systolic dysfunction is a major determinant of survival after AMI, its precursors, among them residual myocardial ischaemia, should be identified. Treatment of ischaemia is known to be associated with improved prognosis and improved LVSF.