Myocardial Contractile Reserve In Patients Research Articles

Left Bundle Branch Block Negatively Affects Coronary Flow Velocity Reserve and Myocardial Contractile Reserve in Nonischemic Dilated Cardiomyopathy

Coronary flow velocity reserve (CFVR) of the left anterior descending coronary artery (LAD) and myocardial contractile reserve are often impaired in nonischemic dilated cardiomyopathy (DCM). Whether they are affected by the presence of left bundle branch block (LBBB) remains unaddressed. The aim of the study was to investigate how LBBB influences CFVR of the LAD and myocardial contractile reserve in patients with DCM. One hundred eighty-one patients with DCM (116 men; mean age, 63±12years) underwent high-dose dipyridamole (0.84mg/kg over 6min) stress echocardiography with CFVR evaluation of the LAD by Doppler. All patients had ejection fractions<40% (mean, 31±8%) and angiographically normal or near normal coronary arteries. CFVR was defined as the ratio between hyperemic peak and basal peak diastolic coronary flow velocities. CFVR>2.0 was considered normal. Inotropic reserve was defined as rest-stress variation in wall motion score index≥0.20. This was a prospective analysis of an unselected sample consecutively enrolled and retrospectively selected. The study group was separated on the basis of presence (n=122) or absence (n=59) of LBBB. Patients with LBBB were older (64±11 vs 59±12 years, P=.004) and had reduced resting ejection fractions (30±9% vs 33±7%, P=.02), CFVR of the LAD (1.96±0.41 vs 2.23±0.73, P=.001), and myocardial contractile reserve (variation in wall motion score index, -0.18±0.17 vs -0.33±0.28; P<.001). On multivariate logistic regression analysis, resting ejection fraction (hazard ratio [HR], 1.15; 95% CI, 1.03-1.29; P=.01), smoking habit (HR, 2.63; 95% CI, 1.23-5.62; P=.01), and LBBB (HR, 2.29; 95% CI, 1.05-5.04; P=.04) were independently associated with reduced CFVR, while restrictive transmitral pattern (HR, 2.56; 95% CI, 1.18-5.55; P=.02), end-diastolic volume (HR, 0.98; 95% CI, 0.67-0.99; P=.02), and LBBB (HR, 2.20; 95% CI, 1.11-4.34; P=.02) independently predicted reduced myocardial contractile reserve. CFVR during vasodilator stress echocardiography is a suitable tool for assessing microvascular dysfunction in routine clinical practice. Patients with DCM and LBBB show more severe forms of microvascular dysfunction, which is related to worse left ventricular function and lack of contractile reserve. Therapeutic interventions to restore microvascular function may improve left ventricular function parameters in patients with DCM.

Tissue Doppler systolic velocity change during dobutamine stress echocardiography predicts contractile reserve and exercise tolerance in patients with heart failure

Dobutamine stress echocardiography (DSE) is widely used to evaluate myocardial contractile reserve in patients with heart failure (HF). The aim of the study was to assess the relationship between the tissue Doppler (TD) mitral annulus systolic velocity (Sm) change during DSE, contractile reserve, and aerobic exercise capacity in HF patients. Sixty-four HF patients (age 67 ± 9 years, 58% with an ischaemic aetiology, and a mean value of the ejection fraction 29 ± 7%) underwent high-dose DSE. The mean value of the TD mitral annulus septal-lateral Sm change was analysed at rest and at peak DSE. All patients underwent also the cardiopulmonary exercise test. With a receiver operating characteristic analysis, a value of 2.02 cm/s obtained as a stress-rest difference in a mean value of the peak systolic velocity of the mitral annulus (Sm) was the best value for diagnosing the myocardial contractile reserve [area under the curve 0.69 (95% CI 0.56-0.80), sensitivity 69% (95% CI 54-81), specificity 80% (95% CI 45-97)]. The patient population was divided into two groups: with rest-stress Sm change during DSE ≤ 2.02 cm/s and with rest-stress Sm change >2.02 cm/s. Patients with Sm rest-stress >2.02 change during DSE, compared with patients with rest-stress change ≤2.02, showed a lower incidence of severe diastolic dysfunction at rest (16 vs. 46%, P= 0.039) and lower E/Ea values (11 ± 5 vs. 15 ± 6, P = 0.005), similar ejection fraction at rest but higher ejection fraction at peak DSE (53 ± 14 vs. 41 ± 12%, P = 0.001), better myocardial contractile reserve assessed by a pressure-volume relationship (1.89 ± 2.01 vs. 0.58 ± 1.38 mmHg/mL/m(2), P = 0.004), with a lower end-systolic volume (-46 ± 20 vs. -24 ± 19%, P< 0.001), a higher increase in the ejection fraction (23 ± 10 vs. 12 ± 10%, P = 0.001) during DSE, and better peak oxygen consumption (16 ± 4 vs. 13 ± 2 mL/kg/min, P = 0.01). In patients with HF, the rest-stress variation of mitral annulus systolic velocities during DSE predicts the presence of myocardial contractile reserve and exercise tolerance.

Depressed Myocardial Contractile Reserve in Patients With Obstructive Sleep Apnea Assessed by Tissue Doppler Imaging With Dobutamine Stress Echocardiography

Hypoxia has been suggested to affect myocardial contractile function in patients with obstructive sleep apnea (OSA). We sought to determine whether myocardial contractile reserve (MCR), as evaluated by echocardiographic tissue Doppler imaging with dobutamine stress (TDDS), might be depressed in OSA patients. Thirty patients with suspected OSA (25 men and 5 women; mean age, 51 +/- 11 years [+/- SD]) underwent overnight polysomnography and TDDS. Peak myocardial systolic velocity (Sm) and peak myocardial early diastolic velocity (Em) in the 12 myocardial segments of the left ventricular (LV) walls were averaged, and the mean Sm and Em during TDDS were compared between patients with apnea-hypopnea index (AHI) <15/h (group 1, n = 13) and those with AHI >/= 15/h (group 2, n = 17). MCR was calculated as the difference between the resting and peak Sm during TDDS. In both groups, Sm increased dose dependently during TDDS. However, the relative increase in Sm was significantly lower in group 2, resulting in a lower value of MCR (5.5 +/- 1.2 cm/s vs 7.4 +/- 1.3 cm/s, p < 0.001). The Em was lower in group 2 compared with group 1 throughout TDDS. MCR was correlated significantly with AHI (r = - 0.67, p < 0.0001), resting Em (r = 0.53, p < 0.005), and body mass index (r = - 0.46, p < 0.05) independent of the LV mass index. OSA can affect MCR, implying an etiologic contribution from repetitive hypoxic events. TDDS could identify subtle abnormalities of OSA-related cardiac involvement.

Cardiac Sympathetic Dysfunction Correlates With Abnormal Myocardial Contractile Reserve in Dilated Cardiomyopathy Patients

We investigated the relationship between iodine-123-metaiodobenzylguanidine (123I-MIBG) findings and myocardial contractile reserve in patients with mild to moderate dilated cardiomyopathy (DCM). Little is known regarding the relationship between cardiac sympathetic nervous function and myocardial contractile reserve in DCM. Twenty-four DCM patients who showed sinus rhythm underwent echocardiography, biventricular catheterization, and myocardial 123I-MIBG scintigraphy. Left ventricular (LV) pressures were measured using a micromanometer-tipped catheter. The myocardial contractile function (LV dP/dt(max)) was determined at rest and during atrial pacing. The messenger ribonucleic acid (mRNA) expressions of intracellular Ca2+-regulatory proteins were analyzed by real-time quantitative reverse transcription-polymerase chain reaction. Myocardial 123I-MIBG accumulation was quantified as a heart-mediastinum ratio (HMR). A significant correlation was observed between the delayed 123I-MIBG HMR and the percentage change in LV dP/dt(max) from the baseline to the peak or critical heart rate (r = 0.64; p < 0.001). The delayed 123I-MIBG HMR was significantly lower in patients showing a worsening change in LV dP/dt(max) than in those showing a favorable change (p < 0.005). The maximum LV dP/dt(max) during pacing and the sarcoplasmic reticulum Ca2+-ATPase (SERCA2) mRNA levels were significantly more reduced in patients with a delayed HMR < or =1.8 than in those with a delayed HMR >1.8 (p < 0.05, respectively). Abnormal myocardial 123I-MIBG accumulation is related to an impaired myocardial contractile reserve and down-regulation of SERCA2 mRNA in DCM. Myocardial 123I-MIBG scintigraphy can be useful in noninvasively evaluating myocardial contractile reserve in patients with mild to moderate DCM.

351 Natriuretic peptides changes at stress-echocardiography predicts myocardial contractile reserve in patients with non-ischemic dilated cardiomyopathy

351 Natriuretic peptides changes at stress-echocardiography predicts myocardial contractile reserve in patients with non-ischemic dilated cardiomyopathy

16.8 Pharmacological radionuclide ventriculography for detection of myocardial contractile reserve in patients after myocardial infarction: low dose dobutamine versus low dose dipyridamole

16.8 Pharmacological radionuclide ventriculography for detection of myocardial contractile reserve in patients after myocardial infarction: low dose dobutamine versus low dose dipyridamole

Mean myocardial velocity mapping in quantifying regional myocardial contractile reserve in patients with impaired left ventricular systolic function: Doppler myocardial imaging study

The aim of this study was to use Doppler myocardial imaging-derived mean myocardial velocity (MMV) at baseline and during low-dose dobutamine stress echocardiography (DSE) to quantify regional contractile reserve of the left ventricle (LV). Sixteen patients (mean age 59 ± 7 years) with coronary artery disease and regional left ventricular wall motion abnormalities were studied. During each increment of Dobutamine infusion, 6 2-dimensional transthoracic apical images were acquired in standard gray-scale and Doppler myocardial imaging modes at 30° steps over 180°. For the analysis, the LV was divided into 18 segments. For each segment, both wall motion score and MMV obtained in systole and both early and late diastole were measured at baseline and at each stage of DSE. In viable segments by wall motion score, MMV increased during DSE in systole and in early and late diastole. In contrast, in nonviable segments, MMV did not change during DSE. Mean myocardial velocity mapping is a promising new approach to quantify regional myocardial contractile reserve of the LV.

Mean Myocardial Velocity Mapping in Quantifying Regional Myocardial Contractile Reserve in Patients with Impaired Left Ventricular Systolic Function: Doppler Myocardial Imaging Study

Mean Myocardial Velocity Mapping in Quantifying Regional Myocardial Contractile Reserve in Patients with Impaired Left Ventricular Systolic Function: Doppler Myocardial Imaging Study

Prognostic implications of myocardial contractile reserve in patients with ischemic cardiomyopathy.

The extent and degree of myocardial viability is an important parameter in the risk stratification of patients with significant left ventricular dysfunction due to coronary artery disease (CAD). Although several imaging modalities can identify viable myocardium, dobutamine stress echocardiography has gained considerable importance as an accurate, safe, and reliable method. In patients with significant left ventricular dysfunction secondary to CAD, identifying the presence and extent of contractile reserve and, therefore, viable myocardium, during low dose dobutamine infusion can predict recovery of left ventricular function postrevascularization, survival, and future cardiac events.

Prognostic implications of myocardial contractile reserve in patients with coronary artery disease and left ventricular dysfunction

OBJECTIVESThis study was performed to assess the prognostic implications of myocardial contractile reserve (MCR) in patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction.BACKGROUNDMCR during dobutamine stress echocardiography (DSE) identifies viable myocardium that may improve in function after revascularization. Whether revascularization influences prognosis of patients with MCR has not been determined.METHODSWe performed DSE in 80 patients with CAD and LV dysfunction (ejection fraction ≤40%). Viable myocardium was defined in dysfunctional myocardial segments as enhanced thickening and contraction during low-dose dobutamine (5 to 10 mcg/kg/min). Serial prospective follow-up was obtained in all patients (mean follow-up 2.2 ± 1.1 years).RESULTSAmong 52 patients treated medically, there were 20 cardiac deaths. By multivariate analysis, the number of dysfunctional segments demonstrating MCR was the strongest predictor of survival (p < 0.03). Patients with MCR had better initial survival during medical therapy than did those without MCR, but this survival advantage was not maintained beyond three years. In contrast, survival was excellent in patients with MCR who underwent myocardial revascularization. Among 58 patients with MCR in ≥5 myocardial segments, survival at three years was 93 ± 6% in the 24 patients who were revascularized but only 49 ± 15% in the 34 treated medically (p < 0.02).CONCLUSIONSMyocardial contractile reserve is a significant predictor of survival in patients with CAD and LV dysfunction undergoing medical therapy. Although patients with MCR have an initial survival advantage, this advantage is lost over the course of three years. In contrast, survival in patients with significant MCR is enhanced by revascularization.

Myocardial Contractile Reserve as Prognostic Determinant in Patients With Idiopathic Dilated Cardiomyopathy Without Overt Heart Failure

To assess the prognostic significance of myocardial contractile reserve in patients with idiopathic dilated cardiomyopathy (DCM) without overt heart failure (New York Heart Association functional class I or II), seventy-one patients underwent exercise radionuclide angiography in addition to clinical, radiographic, hemodynamic, and echocardiographic evaluations. Myocardial contractile reserve was assessed as left ventricular ejection fraction (LVEF) during peak exercise minus LVEF at rest (delta LVEF). During an average of 49 months, 18 patients died of the disease. Cox's proportional-hazards regression analysis showed that the delta LVEF was the most powerful and independent discriminator for survival (p = 0.0002). Ejection time (p = 0.0029) and cardiothoracic ratio (p = 0.017) were the second and third most predictive variables, respectively. Evaluation of the delta LVEF, which reflects residual myocardial contractile reserve, can provide important information about the prognosis of patients with DCM and mild symptoms.