Effect of the isolated left bundle branch block on systolic and diastolic functions of left ventricle.

BACKGROUND: We planned this study to evaluate the effects of left bundle branch block (LBBB) on systolic and diastolic functions of left ventricle (LV) that have not previously been investigated in detail. MATERIAL AND METHODS: Forty-five cases diagnosed as isolated LBBB according to the standard electrocardiographic criteria (group I, mean age: 60 +/- 12 years) were taken as the case group and 65 cases with normal conduction system (group II, mean age 58 +/- 14 years) were taken as the control group. Echocardiography was performed to all patients and coronary angiography was performed to 21 patients in group I and 35 patients in group II. In addition to standard systolic and diastolic function parameters, isovolumetric relaxation time (IRT), isovolumetric contraction time (ICT), and ejection time (ET) were measured by echocardiography, and the myocardial performance index (MPI) [(IRT+ICT)/ET] was calculated. LV end-diastolic pressure was calculated for the patients undergoing coronary angiography. RESULTS: In group I, LV end-systolic diameter was greater (3.1 +/- 0.4 cm vs 2.8 +/- 0.4 cm, P <.001) and ejection fraction was lower (64% +/- 6% vs 68% +/- 6%, P <.001) than those of group II. Rapid filling deceleration time and rate was markedly different in group I (respectively, 133 +/- 50 ms vs 166 +/- 24 ms, P <.001; 608 +/- 291 cm/s(2) vs 383 +/- 116 cm/s(2), P <.001). In addition, it was found that LBBB caused shortening of LV diastolic period and ET markedly (respectively, 347 +/- 116 ms vs 394 +/- 106 ms, P =.03; 255 +/- 40 ms vs 294 +/- 21 ms, P <.001) and prolongation of IRT and ICT (respectively; 124 +/- 36 ms vs 91 +/- 16 ms, 96 +/- 35 ms vs 38 +/- 9 ms, P <.001). The MPI was predominantly higher in group I (0.89 +/- 0.29 vs 0.40 +/- 0.06, P <.001). Invasively determined LV end-diastolic pressure was found higher in group I (14 +/- 3 mm Hg vs 10 +/- 3 mm Hg, P <.001). CONCLUSION: A marked elevation of the LV MPI and end-diastolic pressure, parallel to changes of conventional echocardiographic parameters, in patients with isolated LBBB points out that LBBB causes marked deterioration on LV systolic and diastolic functions.

Importance of left anterior hemiblock development in inferior wall acute myocardial infarction.

The aim of this study was to investigate the clinical and angiographic importance of left anterior hemiblock (LAHB) during acute inferior myocardial infarction (AIMI) by comparing patient groups with and without LAHB after AIMI. One hundred seventy-two patients (141 men and 31 women) between 28 and 84 years of age (mean 55 +/-10 years) with AIMI were included in the study. Patients were divided into 2 groups according to electrocardiogram (ECG) criteria: group I comprised 25 patients in whom ECG pattern characteristic of LAHB developed, group II comprised 147 patients without this pattern. According to the electrocardiogram, patients were placed in group I if the mean QRS axis was deviated to the left < 30 degrees in the frontal plane with the following pattern: increased S-wave voltage and decreased R-wave voltage in leads II, the appearance of a deep S-wave in lead II, and a terminal positive R-wave in lead aVR. Coronary angiography was performed within 2 weeks. A coronary stenosis was considered if the vessel diameter was narrowed by > 50%. The dominant coronary artery was classified as right or left or balanced. The left ventricular ejection fraction (LVEF) was calculated from left ventriculography. The mean age of the patients in group I was significantly higher (58 vs 54 years, p = 0.007), while the risk factors were similar in both groups. Left anterior descending (LAD) and multi-vessel coronary artery disease (CAD) were found to be significantly higher in group I compared with group 11 (80% vs 38%, p=0.0001; 84% vs 52%, p=0.001, respectively). The mean LVEF was found to be lower in group I (51% vs 56%, p=0.04). Peak creatine phosphokinase MB (CKMB) values were not different (216 vs 162 IU/L, p = 0.09). The frequency of left dominant or balanced coronary artery was determined to be higher in group I (44% vs 17%, p = 0.018). LAHB development during AIMI can be an indicator of LAD lesions, multivessel coronary artery disease, and impaired left ventricular systolic function.