In the acute phase of myocardial infarction (AMI), ischemic phenomena may affect the strength and timing of myocardial contraction.

To correlate intraventricular delays to systolic, diastolic and performance parameters of the left ventricle (LV) and to heart failure occurrence in AMI patients.

A total of 372 consecutive patients (mean age: 61.6±12.4 years) who presented with an AMI were prospectively enrolled. Echocardiographic evaluation was carried out within 24-36 hours. Six basal LV segments were explored by pulsed tissue Doppler imaging (TDI) for electromechanical delays. Intraventricular mechanical delay (IMD) was then calculated from the difference between the earliest and most delayed sites. Correlations were assessed by the nonparametric Spearman rho test, and means were compared using Kruskall-Wallis and Mann-Whitney tests were used for correlations and

The IMD (30.3ms±13.72ms) was not correlated to the location and extent of the AMI. The IMD was correlated to the cardiac output (Rho=-0.27, p=0.003) and to the mitral annular systolic velocity (lateral: Rho=0.18, p=0.027 and septal: Rho=-0.37, p<0.0001) but not significantly to the LV ejection fraction (Rho=-0.08, p=0.31). The IMD was also correlated to diastolic parameters: the mitral annular early diastolic velocity (E’) (Rho=-0.26, p=0.002) and the early diasolic mitral flow velocity/ late diastolic mitral flow velocity ratio (E/A) (Rho=-0.18, p=0.03). The IMD was correlated as well to the LV myocardial performance index measured by conventional Doppler (Rho=-0.29, p<0.0001) or by TDI method (Rho=-0.26, p=0.002). Patients with an IMD >42.5ms had a higher rate of in-hospital heart failure (35.0% versus 4.7%, p<0.0001) with a hazard ratio (HR) = 10.9 (95% confidence interval 3.2 to 37.2).

acute dyssynchrony in patients with AMI could be a marker or a factor of cardiac dysfunction.