Early detection of myocardial viability by hyperbaric oxygenation in patients with acute myocardial infarction treated with thrombolysis.

Hyperbaric oxygen treatment (HBO) could transiently reverse hypoxia during acute myocardial infarction (AMI). In order to evaluate whether early HBO can identify viable segments after AMI, improvement of wall motion score index (WMSI) after HBO was compared to dobutamine stress echocardiography (DSE). Thirty-one patients with first AMI treated with thrombolysis received 100% oxygen at 2 technical atmospheres for 1 h within 24 h of the onset of chest pain. All patients underwent echocardiography before and after HBO and during DSE. Improvements in WMSI after HBO, as well as during DSE were considered as proof of viability. Total of 186 akinetic segments were detected before HBO. Functional recovery was defined at 73 after HBO and 113 segments were fixed. Eighty-one segments improved contraction with DSE. WMSI improved before HBO compared to the one after HBO (1.79 vs. 1.65, p = 0.024) and DSE (1.79 vs. 1.60, p < 0.001). Close relationship between WMSI after HBO and DSE was found (r = 0.417, p = 0.022). Sensitivity and specificity of HBO for viability were 73% and 85%, respectively. HBO may identify viable myocardium as early as day one after AMI. The highest number of responding segments was detected in patients who received HBO within shortest intervals following the onset of chest pain.

Relation of myocardial histomorphometric features and left ventricular contractile reserve assessed by high-dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: This study was designed to determine the relationship between histomorphometric features and contractile reserve assessed by high-dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy. METHODS: Twenty-four consecutive patients (21 men, aged 43.4+/-8.7 years) with idiopathic dilated cardiomyopathy underwent dobutamine stress echocardiography. Wall motion score index, ejection fraction, cardiac power output and end-systolic pressure/volume ratio were used as indices of left ventricular contractility. Left ventricular endomyocardial biopsy specimens (3-5 per patient) were routinely processed and stained with Masson trichrome, interstitial fibrosis and myocyte diameter were calculated quantitatively. RESULTS: Myocyte diameter and interstitial fibrosis showed strongest correlation with change in wall motion score index (r=-0.667, p<0.001, and r=-0.567, p=0.004, respectively), followed by change in ejection fraction (r=-0.603, p=0.002, and r=-0.467, p=0.021, respectively). Interstitial fibrosis showed no correlation with change of cardiac power output and end-systolic pressure/volume ratio, whereas myocyte diameter was associated with change of both indices (r=-0.565, p=0.004, and r=-0.455, p=0.025). CONCLUSIONS: Contractile reserve elicited by high-dose dobutamine is strongly related to the degree of histological disruption in patients with idiopathic dilated cardiomyopathy.

Adjunctive effect of hyperbaric oxygen treatment after thrombolysis on left ventricular function in patients with acute myocardial infarction.

BACKGROUND: The role of hyperbaric oxygen in patients with acute myocardial infarction is controversial, ranging from not beneficial to having a favorable effect. This randomized study was conducted to further assess the benefit of hyperbaric oxygen treatment after thrombolysis on left ventricular function and remodeling in patients with acute myocardial infarction. METHODS: Seventy-four consecutive patients with first acute myocardial infarction were randomly assigned to treatment with hyperbaric oxygen treatment combined with streptokinase (HBO+) or streptokinase alone (HBO-). RESULTS: There was a significant decrease of end-systolic volume index from the first day to the third week in HBO+ patients compared with HBO- patients (from 30.40 to 28.18 vs from 30.89 to 36.68 mL/m2, P <.05) accompanied with no changes of end-diastolic volume index in HBO+ compared with increased values in HBO- (from 55.68 to 55.10 vs from 55.87 to 63.82 mL/m2, P <.05). Ejection fraction significantly improved in the HBO+ group and decreased in the HBO- group of patients after 3 weeks of acute myocardial infarction (from 46.27% to 50.81% vs from 45.54% to 44.05 %, P <.05). CONCLUSIONS: Adjunctive hyperbaric oxygen therapy after thrombolysis in acute myocardial infarction has a favorable effect on left ventricular systolic function and the remodeling process.

Hyperbaric oxygen treatment does not affect left ventricular chamber stiffness after myocardial infarction treated with thrombolysis.

BACKGROUND: It has been shown that transient increase in left ventricular stiffness, assessed by Doppler-derived early filling deceleration time, occurs during the first 24 to 48 hours after myocardial infarction but returns to normal within several days. It has been reported that hyperbaric oxygen treatment has a favorable effect on left ventricular systolic function in patients with acute myocardial infarction treated with thrombolysis. However, there are no data on the effects of hyperbaric oxygen on diastolic function after myocardial infarction. METHODS: To assess acute and short-term effects of hyperbaric oxygen on left ventricular chamber stiffness, we studied 74 consecutive patients with first acute myocardial infarction who were randomly assigned to treatment with hyperbaric oxygen combined with streptokinase or streptokinase alone. After thrombolysis, patients in the hyperbaric oxygen group received 100% oxygen at 2 atm for 60 minutes in a hyperbaric chamber. All patients underwent 2-dimensional and Doppler echocardiography 1 (after thrombolysis), 2, 3, 7, 21, and 42 days after myocardial infarction. RESULTS: Patient characteristics, including age, sex, risk factors, adjunctive postinfarction therapy, infarct location, and baseline left ventricular volumes and ejection fraction, were similar between groups (P >.05 for all). For both groups, deceleration time decreased nonsignificantly from day 1 to day 3 and increased on day 7 (P <.001, for both groups), increasing nonsignificantly subsequently. The E/A ratio increased in the entire study group throughout the time of study (P <.001, for both groups). The pattern of changes of deceleration time was similar in both groups (P >.05 by analysis of variance), as was in subgroups determined by early reperfusion success. CONCLUSIONS: These data in a small clinical trial do not support a benefit of hyperbaric oxygen on left ventricular diastolic filling in patients with acute myocardial infarction treated with thrombolysis.

Comparative value of single-beat load-independent contractility indices in dilated cardiomyopathy and mitral regurgitation.

OBJECTIVE: We sought to compare single-beat estimates of contractility indices. METHODS: Echocardiography was performed for 6 control patients, 8 patients with dilated cardiomyopathy, and 9 patients with mitral regurgitation (MR). Left ventricular volume waveform, outflow tract velocities, and mitral annulus velocities were recorded with carotid tonometry. Numeric simulations were used to generate the same data while varying contractility, compliance, and MR. Estimates of elastance (normalized systolic and bilinearly approximated), preload-recruitable stroke work, and preload-adjusted maximal power were calculated. RESULTS: Normalized systolic and bilinearly approximated elastance were decreased in patients with dilated cardiomyopathy (P <.005 for both) and MR (P =.0002 and.02, respectively). Preload-recruitable stroke work and preload-adjusted maximal power were decreased in patients with dilated cardiomyopathy only (P <.005 for both). Simulations confirmed that these differences are a result of dissimilar behavior of estimates if MR or compliance change. CONCLUSIONS: Single-beat indices are decreased in dilated cardiomyopathy, but in MR show dissimilar behavior.

Right vs. left ventricular contractile reserve in one-year prognosis of patients with idiopathic dilated cardiomyopathy: assessment by dobutamine stress echocardiography.

AIM: To determine prognostic implications of the assessment of right (RV) vs. left ventricular (LV) contractile reserve with dobutamine echocardiography in patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Forty-eight consecutive patients (41 male, NYHA class III/IV 13 patients, LV ejection fraction 19+/-8%) were subjected to dobutamine stress echocardiography in incremental stages lasting 5 min each. Contractile reserve was defined as the difference between the values of LV ejection fraction and RV fractional area change obtained at peak dobutamine dose and the baseline values. Patients were followed for one year after enrollment for combined end-point of cardiac death, partial left ventriculectomy and hospitalization for congestive heart failure. During the follow-up 15/48 patients reached combined end-point. Patients who reached end-point had lower RV and LV contractile reserves (14+/-5 vs. 8+/-6%, p=0.0014, and 9+/-5 vs. 3+/-2%, p<0.001, respectively). Kaplan-Meier curves demonstrated that both LV and RV contractile reserves can identify patients with dismal prognosis (log rank=17.02 and log rank=14.66, respectively, p<0.001 for both). Multivariate analysis identified dobutamine induced change in LV functional reserve as the only independent predictor of combined end-point (beta=-0.63, p=0.0035). CONCLUSION: Both RV and LV contractile reserves can be used for prognostic stratification in patients with idiopathic dilated cardiomyopathy. It appears that dobutamine induced change in LV functional reserve may better identify patients with dismal prognosis.

[Comparison of prognostic value of high-dose dobutamine stress-echocardiography and exercise testing in patients with idiopathic dilated cardiomyopathy]. / [Uporedni prognosticki znacaj visokodozne dobutaminske stres-ehokardiografije i testa fizickim opterecenjem kod bolesnika s idiopatskom dilatacionom kardiomiopatijom.

INTRODUCTION: It is of the utmost importance to make an accurate assessment of prognosis in patients with idiopathic dilated cardiomyopathy. Both high-dose dobutamine stress-echocardiography and exercise testing have been used for prognostic stratification of these patients. OBJECTIVE: To make head-to-head comparison of high-dose dobutamine stress-echocardiography and exercise testing in prognostic stratification of patients with idiopathic dilated cardiomyopathy. METHODS: A total of 63 consecutive patients (55 men, mean age 50.1 +/- 9.6 years, mean ejection fraction 19.2 +/- 8.4%) with idiopathic dilated cardiomyopathy, left ventricular end-diastolic diameter >60mm, ejection fraction <35%, and adequate echocardiographic window have been studied. Dobutamine stress echocardiography was performed using 5, 10, 20, 30 and 40 mcg/kg/min infusions, in progressive stages lasting 5 minutes each. Wall motion score index and ejection fraction were considered the indices of the left ventricular contractility. Contractile reserve was defined as the difference between the values of these indices obtained at peak dobutamine dose during the test and the baseline values. Exercise testing was performed as supine bicycle ergometry in progressive stages of 25 W lasting 120 seconds each. Patients were followed one year for combined end-point consisting of cardiac death, partial left ventriculectomy and hospitalization for congestive heart failure. RESULTS: Out of 61, 19 (31%) patients met combined end-point during follow-up [cardiac death in 6/61 (10%), partial left ventriculectomy in 4/61 (7%) and hospitalization for heart failure in 9/61 (15%) patients]. Kaplan-Meier survival analysis demonstrated that dobutamine-induced change of wall motion score index was the best parameter for separation of patients in terms of prognosis during the follow-up (log rank=25.34, p<0.001), followed by change of ejection fraction (log rank=16.83, p<0.001) and duration of exercise testing (log rank 13.85, p=0.002). Cox model identified dobutamine-induced change of wall motion score index as the only independent predictor (p<0.001) of combined end-point during one-year follow-up. DISCUSSION: There is a number of studies dealing with the left ventricular contractile indices. These studies are different with respect to studied population, method used to elicit the left ventricular contractile response and the indices of contractile reserve. A number of studies has suggested that the amount of pharmacologically or physically induced change of wall motion score index and ejection fraction can identify patients with dismal prognosis. Peak oxygen consumption is traditionally considered the most accurate prognostic index, but its usefulness has been recently questioned. Our data suggest that high-dose dobutamine stress-echocardiography may be superior to exercise testing for prognostic stratification of patients with idiopathic dilated cardiomyopathy. The reasons for such observation are not clear, but it can be hypothesized that this may be due to multifactorial nature of the exercise tolerance. The most serious potential drawback of methodology is that, because of technical limitations, we did not test peak oxygen consumption in our patients, but since it has been shown that oxygen consumption correlates well with the duration of exercise, we believe that our methodology is valid. CONCLUSION: Both high-dose dobutamine stress-echocardiography and exercise testing can identify patients with dismal prognosis during one-year follow-up, but it appears that dobutamine stress-echocardiography may yield better prognostic significance.

[Effect of thrombolytic therapy on occurrence of complex ventricular arrhythmias in the late hospitalization period in acute myocardial infarct: relation with long-term remodeling of the left ventricle]. / Uticaj tromboliticke terapije na ucestalost kompleksnih komorskih aritmija u kasnoj hospitalnoj fazi akutnog infarkta miokarda: odnos sa dugorocnim remodelovanjem leve komore.

BACKGROUND: The impact of thrombolytic therapy on the incidence of complex ventricular arrhythmias is not yet clarified. The aim of this study was to investigate the impact of thrombolytic therapy on the incidence of complex ventricular arrhythmias, as well as long term association between complex ventricular arrhythmias and left ventricular remodelling, and their impact on five-year lethality. METHODS: Ninety seven consecutive patients with first acute myocardial infarction (streptokinase was administered in 58 patients), underwent 24-hours Holter monitoring at discharge. Ventricular arrhythmias were classified according to Lown classification, and patients were grouped into the group with simple ventricular arrhythmias (Lown class 0 to 2), and the group with complex ventricular arrhythmias (Lown class 3 to 5). Echocardiography was performed at discharge, and six and twelve months after the infarction. Left ventricular volume indexes and ejection fraction was determined using Simpson's biplane formula. RESULTS: In patients with complex ventricular arrhythmias left ventricular volume indexes were higher and ejection fraction was lower throughout the study, whereas wall motion score index was higher one year after the infarction. On the other hand, these variables were similar throughout the follow-up within the groups of patients with and without complex ventricular arrhythmias who received thrombolytic therapy. The incidence of complex ventricular arrhythmias was similar in thrombolyzed and non-thrombolyzed patients (11/58 vs. 5/39). There was no difference in five year lethality between patients with and without complex ventricular arrhythmias (4/16 vs. 13/81 patients). CONCLUSION: Our data indicated that left ventricular remodelling in patients with complex ventricular arrhythmias was not progressive after hospital discharge. The presence of complex ventricular arrhythmias was not associated with the increased five-year lethality, despite of more pronounced left ventricular remodelling. It occurred that thrombolysis per se had no influence on the incidence of complex ventricular arrhythmias in the late hospital phase after the first acute myocardial infarction.