Long-term prognosis of left ventricular lead

Transvenous left ventricular (LV) lead implantation is on the increase due to cardiac resynchronization therapy (CRT). However, there has been paucity of data on the prognosis of LV lead. Consecutive 32 patients with LV lead for CRT (n=22) or pacemaker (n=10) were subjected. Serial changes in pacing threshold and impedance along with lead-related complications were evaluated. Over 2 yr follow-up, there was no significant change in relative threshold voltage to the initial value (100%, 110%, 89.6%, and 79.6% at baseline, 1, 6, and 24 months respectively, P=0.62) as well as lead impedance (816±272, 650±178, 647±191, and 590±185 ohm at baseline, 1, 6, and 24 months respectively, P=0.80). The threshold change was not affected by lead position, lead polarity, and indication of lead implantation. The cumulative rates of lead revision were 6.3% (n=2) and 9.4% (n=3) in 6 month and 2 yr follow-up, respectively. One case of phrenic nerve capture at left lateral decubitus position was detected 1 month after the implantation. However, there were no serious complications over 2 yr period. In conclusion, transvenous LV lead implantation showed favorable long-term prognosis. Pacing parameters remained stable without significant changes over 2 yr follow-up.     

Transesophageal left ventricular electrogram-recording and temporary pacing to improve patient selection for cardiac resynchronization

Cardiac resynchronization therapy (CRT) with biventricular pacing (BV) is an established therapy for heart failure (HF) patients with inter- and intraventricular conduction delay. The aim of this pilot study was to test the feasibility of both transesophageal measurement of left ventricular (LV) electrical delay and transesophageal LV pacing prior to implantation, to better select patients for CRT. Esophageal TO8 Osypka catheter was perorally applied in 30 HF patients in position of maximum LV deflection to measure LV electrical delay and to study arterial pulse pressure (PP) during transesophageal bipolar LV pacing. There were 15 responders with a PP increase of a mean 65 ± 24 mmHg to 79 ± 27 mmHg (P < 0.001) and a mean LV electrical delay of 86.8 ± 33 ms. The 15 non-responders with poor PP increase of a mean 63.5 ± 23.5 mmHg to 64.1 ± 23.9 mmHg (P = 0.065) had a significantly smaller LV electrical delay of 36 ± 21 ms (P < 0.001). During a 34 ± 26 month CRT follow-up, the responders New York Heart Association (NYHA) class improved from 3.1 ± 0.35 to 2.1 ± 0.35 (P < 0.001). Determination of left ventricular electrical delay by transesophageal electrogram recording and transesophageal left ventricular pacing may be additional useful techniques to improve patient selection for CRT.     

Evaluation of left ventricular dyssynchrony using combined pulsed wave and tissue Doppler imaging

Introduction

The combination of pulsed wave (PW) and tissue Doppler imaging (TDI) has been proposed as a new method to assess left ventricular (LV) mechanical dyssynchrony (LVMD), but results have not been validated. We investigated the correlation of a combination of PW and TDI with a positive response to cardiac resynchronization therapy (CRT).

Material and methods

We studied 108 consecutive patients who received CRT. Patients with atrial fibrillation were excluded. The time difference (T_PW-TDI) between onset of QRS to the end of LV ejection by PW (T_PW) and onset of QRS to the end of the systolic wave in LV basal segments with greatest delay by TDI (T_TDI) was measured before CRT and during short-term and long-term follow-up.

Results

The T_PW-TDI interval before CRT was 74 ±48 ms. Intra-observer variabilities for T_PW and T_TDI were 1.5 ±0.24% and 1 ±0.17%. Inter-observer variabilities for T_PW and T_TDI were 1 ±0.36% and 1 ±0.64%, respectively. T_PW-TDI > 50 ms was defined as the cutoff value for diagnosis of LVMD by receiver operating curve (ROC) analysis. During follow-up of 15 ±11 months, the sensitivity and specificity of TP_PW-TDI to predict a positive response to CRT were 98% and 82%, respectively. The area under the ROC curve was 0.92. There was a significant agreement between LVMD determined by T_PW-TDI and the positive response to CRT (κ=0.80).

Conclusions

Left vertricular dyssynchrony detected by the method combining PW and TDI demonstrated a high reproducibility, sensitivity, specificity and agreement with a positive response to CRT.     

Left ventricular mural thrombus following myocardial infarction--a follow up study

Left Ventricular mural thrombus detected by echocardiography in 41 patients after myocardial infarction (MI) were followed up for 4 years. Thirty eight patients were males and mean age of study population was 52.4 years. Echocardiography revealed predominant mural type of thrombi (38 patients) and none showed mobility. All of them showed regional wall motion abnormality (RWMA) and Left Ventricular (LV) aneurysm was found in 28 patients. Embolic events were observed in 6 patients and 1 patient died following embolic stroke. Follow up study revealed persistent left ventricular thrombus in 19 patients and risk factors detected were severe LV dysfunction and LV aneurysm. Six patients had spontaneous resolution and 6 had resolution of the thrombus after anticoagulants. While anticoagulant therapy was very effective in preventing embolism after recent MI (within 3 weeks), it was found not useful in chronic LV thrombi. We observed ongoing embolic risk in chronic LV thrombi with LV aneurysms but a randomised trial is needed to decide the role of anticoagulants in such situation.     

联合应用培哚普利和氯沙坦改善心肌梗死后左室重构和心功能的临床研究

目的:观察培哚普利和氯沙坦联合治疗对于急性前壁心肌梗死患者左室重构、心功能和血清Ⅲ型前胶原肽(PⅢNP)水平的影响。方法:急性前壁心肌梗死患者,随机分为培哚普利组、氯沙坦组和培哚普利+氯沙坦组。入院后行急诊冠脉造影和介入治疗,术后分别给予:培哚普利2-4mg/d;氯沙坦25-50mg/d;或二者联合。所有患者常规给予抗血小板、抗凝、他汀类调脂药等。3个月后超声心动图检测左室大小、左室容量和左室射血分数。酶免法和放免法测定血液脑钠肽(BNP)、C反应蛋白(CRP)和PⅢNP水平。结果:3组患者的基础临床特征无显著区别。与基础值相比,3个月后,所有患者均表现出血液中CRP水平下降、BNP和PⅢNP水平上升,且有不同程度的左室扩大和左心功能下降。与培哚普利组和氯沙坦组相比,联合用药组患者CRP、BNP和PⅢNP水平显著降低,且左室扩张和射血功能障碍程度均减轻。血清PⅢNP水平与CRP水平及左室舒张末期容积指数均呈显著正相关(r=0.597,r=0.543,均P0.01),与左室射血分数呈显著负相关(r=-0.565,P0.01)。结论:急性前壁心肌梗死患者,早期联合培哚普利和氯沙坦治疗可以进一步改善左室重构和心功能,其机制可能与抑制胶原合成、抑制心肌纤维化有关。     

Cardioresynchronizing therapy in treatment of cardiac insufficiency

The authors analyze the effectiveness of cardioresynchronizing therapy (CRT) in patients with cardiac insufficiency (CI) and intraventricular conductivity disorder. The results of completed randomized studies (CONTAK-CD, MIRACLE-ICD, MUSTIC-AF, RD-CHF, COMPANION, PATH-CHF, PATH-CHF II, MUSTIC-SR, MIRACLE, MUSTIC-AF, CARE-HF) and their metanalysis are evaluated; drawbacks of these studies are demonstrated. CRT has been demonstrated to increase survival rate due to slowing down CI progress; total mortality falls thanks to CRT even without defibrillation function. High efficacy and safety of CRT in patients with CI and profound systolic dysfunction have been demonstrated; quality of life increases by 7.6 points and by 8 points in patients with III to IV functional class CI. At the same time, there is a need for additional investigations of CRT for adequate selection of patients and optimization of stimulation modes. It is not quite clear yet for what functional class CI CRT will be most effective, which criterion is most important for patient selection, whether biventricular stimulation has advantages over left-ventricular one, and whether it is necessary to stimulate the atriums or their detection is enough. Few studies on chronic atrial arrhythmias have been conducted, thus it is not known to which extent CRT is effective in this category of patients.     

Assessment of synchronized direct mechanical ventricular actuation in a canine model of left ventricular dysfunction

Direct mechanical ventricular actuation (DMVA) is an experimental procedure that provides biventricular cardiac assistance by intracorporeal pneumatic compression of the heart. The advantages this technique has over other assist devices are biventricular assistance, no direct blood contact, pulsatile blood flow, and rapid, less complicated application. Prior studies of nonsynchronized DMVA support have demonstrated that a subject can be maintained for up to 7 days. The purpose of this study was to determine the acute hemodynamic effects of cardiac synchronized, partial DMVA support in a canine model (RVP) of left ventricular (LV) dysfunction. The study consisted of rapidly pacing seven dogs for 4 weeks to create LV dysfunction. At the conclusion of the pacing period, the DMVA device was positioned around the heart by means of a median sternotomy. The animals were then imaged in a 1.5 T whole body high speed clinical MR system, with simultaneous LV pressure recording. Left ventricular pressure-volume (PV) loops of the nonassisted and DMVA assisted heart were generated and demonstrated that DMVA assist shifted the loops leftward. In addition, assist significantly improved pressure dependent LV systolic parameters (left ventricular peak pressure and dp/dt max, p < 0.05), with no diastolic impairment. This study demonstrates that DMVA can provide synchronized partial assist, resulting in a decrease in the workload of the native heart, thus having a potential application for heart failure patients.     

Medroxyprogesterone acetate aggravates oxidative stress and left ventricular dysfunction in rats with chronic myocardial infarction

The role of estrogens during myocardial ischemia has been extensively studied. However, effects of a standard hormone replacement therapy including 17β-estradiol (E2) combined with medroxyprogesterone acetate (MPA) have not been assessed, and this combination could have contributed to the negative outcomes of the clinical studies on hormone replacement. We hypothesized that adding MPA to an E2 treatment would aggravate chronic heart failure after experimental myocardial infarction (MI). To address this issue, we evaluated clinical signs of heart failure as well as left ventricular (LV) dysfunction and remodeling in ovariectomized rats subjected to chronic MI receiving E2 or E2 plus MPA. After eight weeks MI E2 showed no effects. Adding MPA to E2 aggravated LV remodeling and dysfunction as judged by increased heart weight, elevated myocyte cross-sectional areas, increased elevated left ventricle end diastolic pressure, and decreased LV fractional shortening. Impaired LV function in rats receiving MPA plus E2 was associated with increased cardiac reactive oxygen species generation and myocardial expression levels of NADPH oxidase subunits. These results support the interpretation that adding MPA to an E2 treatment complicates cardiovascular injury damage post-MI and therefore contributes to explain the adverse outcome of prospective clinical studies.     

Mid-Term Outcomes in Patients Implanted with Cardiac Resynchronization Therapy

We applied cardiac resynchronization therapy (CRT) for desynchronized heart failure patients. We evaluated clinical outcomes including morbidity, mortality, and echocardiographic parameters in 47 patients with implanted CRT in Korea from October 2005 to May 2013. The combined outcomes of hospitalization from heart failure, heart transplantation and death were the primary end point. Median follow-up period was 17.5 months. The primary outcomes listed above occurred in 10 (21.3%) patients. Two patients (4.3%) died after CRT and 8 (17%) patients were hospitalized for recurrent heart failure. Among patients hospitalized for heart failure, 2 (4.3%) patients underwent heart transplantation. The overall free rate of heart failure requiring hospitalization was 90.1% (95% CI, 0.81-0.99) over one year and 69.4% (95% CI, 0.47-0.91) over 3 yr. We observed improvement of the New York Heart Association classification (3.1±0.5 to 1.7±0.4), decreases in QRS duration (169.1 to 146.9 ms), decreases in left ventricular (LV) end-diastolic (255.0 to 220.1 mL) and end-systolic (194.4 to 159.4 mL) volume and increases in LV ejection fraction (22.5% to 31.1%) at 6 months after CRT. CRT improved symptoms and echocardiographic parameters in a relatively short period, resulting in low mortality and a decrease in hospitalization due to heart failure.     

Copeptin in Hemodialysis Patients with Left Ventricular Dysfunction

Purpose

Copeptin has been considered as a useful marker for diagnosis and prediction of prognosis in heart diseases. However, copeptin has not been investigated sufficiently in hemodialysis patients. This study aimed to investigate the general features of copeptin in hemodialysis and to examine the usefulness of copeptin in hemodialysis patients with left ventricular dysfunction (LV dysfunction).

Materials and Methods

This study included 41 patients on regular hemodialysis. Routine laboratory data and peptides such as the N-terminal of the prohormone brain natriuretic peptide and copeptin were measured on the day of hemodialysis. Body fluid volume was estimated by bioimpedance spectroscopy, and the E/Ea ratio was estimated by echocardiography.

Results

Copeptin increased to 171.4 pg/mL before hemodialysis. The copeptin had a positive correlation with pre-dialysis body fluid volume (r=0.314; p=0.04). The copeptin level decreased along with body fluid volume and plasma osmolality during hemodialysis. The copeptin increased in the patients with LV dysfunction more than in those with normal LV function (218.7 pg/mL vs. 77.6 pg/mL; p=0.01). Receiver operating characteristic curve analysis showed that copeptin had a diagnostic value in the hemodialysis patients with LV dysfunction (area under curve 0.737; p=0.02) and that the cut-off value was 125.48 pg/mL (sensitivity 0.7, specificity 0.8, positive predictive value 0.9, negative predictive value 0.6).

Conclusion

Copeptin increases in hemodialysis patients and is higher in patients with LV dysfunction. We believe that copeptin can be a useful marker for the diagnosis of LV dysfunction in hemodialysis patients.     

A new baseline scoring system may help to predict response to cardiac resynchronization therapy

Introduction

The PROSPECT trial reported no single echocardiographic measurement of dyssynchrony is recommended to improve patient selection for cardiac resynchronization therapy (CRT).

Material and methods

In 100 consecutive patients who received CRT, we analyzed 27 ECG and echocardiographic variables to predict a positive response to CRT defined as a left ventricular (LV) end systolic volume decrease of ≥ 15% after CRT.

Results

Right ventricular (RV) pacing-induced left bundle branch block (LBBB), time difference between LV ejection measured by tissue Doppler and pulsed wave Doppler (T_TDI-PW), and wall motion score index (WMSI) were significantly associated with positive CRT response by multivariate regression. We assigned 1 point for RV pacing-induced LBBB, 1 point for WMSI ≤ 1.59, and 2 points for T_TDI-PW > 50 ms. Overall mean response score was 1.79 ±1.39. Cutoff point for response score to predict positive response to CRT was > 2 by receiver operating characteristic (ROC) analysis. Area under ROC curve was 0.97 (p = 0.0001). Cardiac resynchronization therapy responders in patients with response score > 2 and ≤ 2 were 36/38 (95%) and 7/62 (11%, p < 0.001), respectively. After age and gender adjustment, the response score was related to CRT response (OR = 45.4, p < 0.0001).

Conclusions

A response score generated from clinical, ECG and echocardiographic variables may be a useful predictor for CRT response. However, this needs to be validated.     

Triple-site pacing: a new supported therapy approach for bridge to recovery with a left ventricular assist system in a patient with idiopathic dilated cardiomyopathy

Left ventricular assist devices (LVAD) are widely used as bridges to cardiac transplantation or for destination therapy. LVAD support may also function as a bridge to ventricular recovery, but a sufficient rate of recovery has not been obtained, even with various adjuvant therapies. Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure, and there is a report of successful weaning off LVAD with CRT. However, some patients with CRT could not improve their cardiac function because of residual dyssynchrony. Herein, we describe a case of a successful bridge to recovery with triple-site pacing for residual dyssynchrony after biventricular pacing. A 34-year-old woman with heart failure due to dilated cardiomyopathy whose condition deteriorated underwent Toyobo LVAD implantation, resulting in improvement of the left ventricular ejection fraction (LVEF) from 12 to 36%. Because of left ventricular dyssynchrony, we performed CRT, but residual dyssynchrony impeded cardiac recovery. We inserted an additional ventricular lead at the right ventricular outlet to achieve triple-site pacing in order to obtain complete synchronization. The LVEF improved to 45%, and the patient was successfully weaned off the LVAD. In LVAD-supported cases of persistent left ventricular dyssynchrony with CRT, implantation of triple-site pacing could potentially accelerate recovery.     

A prospective evaluation of the angiotensin-converting enzyme D/I polymorphism and left ventricular remodeling in the 'Healing and Early Afterload Reducing Therapy' study

The D/I (deletion, D, insertion, I) polymorphism of the angiotensin-converting enzyme (ACE) gene has been extensively studied for its association with a number of cardiovascular and other disease states. However, its potential association with differential clinical efficacy of ACE inhibitors (ACE-I) administered to patients who had suffered a myocardial infarction (MI), i.e. the prevention of left ventricular (LV) remodeling, has so far not been specifically studied. The aim of the study was to investigate whether the D/I polymorphism of the ACE gene is associated with the incidence of post-MI LV remodeling in patients drawn from the 'Healing and Early Afterload Reducing Therapy' (HEART) Study. The ACE D/I polymorphism was characterized by the polymerase chain reaction (PCR) in 265 subjects from the 'Healing and Early Afterload Reducing Therapy' Study, a double-blind, placebo-controlled trial with the objective of determining whether early or delayed administration of the ACE-I, ramipril, in patients with acute anterior wall MI would be optimal in reducing LV enlargement. Selected frequencies for the ACE D and I alleles were 0.59 and 0.41 (placebo-high dose group), 0.56 and 0.44 (low dose-low dose group), and, 0.60 and 0.40 (high dose-high dose group), respectively. All observed genotype frequencies were in Hardy-Weinberg equilibrium. There was no evidence for an association between genotype and outcome regarding LV size or function, nor with the initial blood pressure response after ACE-I administration (adjusted for covariates). Our data provide no evidence for an association of the ACE D/I polymorphism with the risk of LV remodeling post-MI in the presence of ACE-I therapy, and therefore do not suggest that differential clinical efficacy of ACE-inhibitors is related to this genetic marker.     

Improved clinical course of autologous skeletal myoblast sheet (TCD-51073) transplantation when compared to a propensity score-matched cardiac resynchronization therapy population

We recently reported a multi-center, single-arm, phase II study that evaluated the efficacy and safety of autologous skeletal myoblast sheet (TCD-51073) transplantation. The advantage of this procedure over a control group has not yet been analyzed. Seven patients with advanced heart failure due to ischemic etiology (TCD-51073 group, New York Heart Association (NYHA) class III; left ventricular ejection fraction (LVEF) <35 %) refractory to optimal medical and coronary revascularization therapy, received TCD-51073 at 3 study centers between 2012 and 2013 with a 2-year follow-up period. As previously reported, 112 patients received cardiac resynchronization therapy (CRT) with follow-up at the University of Tokyo Hospital between 2007 and 2014. Of them, 21 patients were selected for the control group by propensity score matching. No significant difference in baseline variables between the groups was observed. LVEF and NYHA class improved significantly in the TCD-51073 group during the 6-month study period (p < 0.05). During the 2-year follow-up, 7 patients (33 %) in the CRT group and no patient in the TCD-51073 group died due to cardiac disease or received VAD implantation (p = 0.128 by the log-rank test). In conclusion, transplantation of TCD-51073 is clinically advantageous in facilitating LV reverse remodeling, improving HF symptoms, and preventing cardiac death in patients with ischemic etiology when compared to background-matched patients receiving CRT.     

An integrated platform for image-guided cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic resonance imaging (MRI), may improve outcome by guiding the physician for optimal LV lead positioning. Whole heart MR data can be processed to yield detailed anatomical models including the coronary veins. Cine MR data can be used to measure the motion of the LV to determine which regions are late-activating. Finally, delayed Gadolinium enhancement imaging can be used to detect regions of scarring. This paper presents a complete platform for the guidance of CRT using pre-procedural MR data combined with live x-ray fluoroscopy. The platform was used for 21 patients undergoing CRT in a standard catheterization laboratory. The patients underwent cardiac MRI prior to their procedure. For each patient, a MRI-derived cardiac model, showing the LV lead targets, was registered to x-ray fluoroscopy using multiple views of a catheter looped in the right atrium. Registration was maintained throughout the procedure by a combination of C-arm/x-ray table tracking and respiratory motion compensation. Validation of the registration between the three-dimensional (3D) roadmap and the 2D x-ray images was performed using balloon occlusion coronary venograms. A 2D registration error of 1.2 ± 0.7?mm was achieved. In addition, a novel navigation technique was developed, called Cardiac Unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device detection. This allowed more intuitive navigation as the entire 3D scene was displayed simultaneously on a 2D plot. The accuracy of the unfold navigation was assessed off-line using 13 patient data sets by computing the registration error of the LV pacing lead electrodes which was found to be 2.2 ± 0.9?mm. Furthermore, the use of Unfold Navigation was demonstrated in real-time for four clinical cases.     

Emergency implantation of a left ventricular assist device in adolescents with biventricular failure

Adolescents with congestive cardiomyopathy who present with intractable arrhythmia or progressive ventricular failure have a very poor prognosis and often die awaiting cardiac transplantation (CTx). We present our recent experience with a pneumatically powered left ventricular assist device (LVAD) implanted emergently to salvage adolescents with severe biventricular failure. Four patients, aged 15-17 years, body surface areas of 1.5-1.7 m2, with dilated cardiomyopathy (LV diastolic dimension, 7.1-8.3 cm); two presented with cardiovascular collapse, one with refractory ventricular tachycardia, and one with cardiac arrest. Hemodynamic and biochemical data before and 1 week after LVAD placement are expressed as mean and range values. None of the patients required right ventricular assist, and all patients achieved functional recovery while on LVAD support (8-71 days). Currently, all four patients are alive (11-22 months) after successful CTx. We conclude that emergency implantation of an LVAD in adolescents with biventricular heart failure can be life saving. As has been shown in the adult population, such a ventricular assist system restores normal circulatory hemodynamics, reverses multi-organ dysfunction, and provides a "safe" bridge to transplantation.     

Bax, a predictive marker for therapeutic response to preoperative chemoradiotherapy in patients with rectal carcinoma

In an attempt to improve local control and survival in patients with advanced rectal carcinoma, neoadjuvant chemoradiation therapy (CRT) has been increasingly used in patient management. However, a significant proportion of patients shows poor response to adjuvant CRT. Thus, the ability to predict CRT responsiveness in patients with rectal cancer would benefit effective management. Several molecular markers related to regulation of cell cycle, apoptosis, or DNA repair have been proposed as candidate predictors of therapeutic response to CRT, but, to date, none has been definitively proven to be predictive of CRT response. To evaluate the use of various molecular markers as predictors of the response to CRT in rectal carcinoma, we investigated immunohistochemical expressions of p53, p21 WAF1/CIP1 , Bcl-2, Bax, Ki-67, Ku-70, and 2 new candidate markers (histone deacetylase 1 and metabotropic glutamate receptor 4) in pretreatment biopsy samples of 130 rectal carcinomas. We further compared the expressions of these molecular markers with the pathological responses of the tumors after therapy. We found that Bax expression, among the markers studied, was exclusively related to tumor regression. Its expression was significantly higher in the complete response group as compared with the partial response group (54% versus 29%, P = .017). This result confirms that apoptosis plays an important role in tumor response to CRT and provides evidence that Bax may serve as a predictable molecular marker for chemoradiosensitivity in rectal carcinoma.     

Catch 22: a case of incessant ventricular tachycardia post-left ventricular assist device resulting in right ventricular failure,left ventricular cavity obliteration and failure of endocardial ventricular tachycardia ablation

Ventricular tachycardia (VT) in the setting of left ventricular assist device (LVAD) therapy has been well described. We present a case of incessant ventricular tachycardia resulting in severe right ventricular (RV) failure and subsequent left ventricular (LV) cavity obliteration, which in turn diminished the feasibility of initial attempt at VT ablation.     

Cardiovascular ultrasound: applications for the assessment of cardiac function

Congestive heart failure(CHF) is usually associated with impaired left ventricular(LV) systolic function, and thus, the measurement of systolic function is an essential component of the evaluation of any patients with known or suspected cardiac disease. Among many parameters, most frequently used are LV percent fractional shortening and ejection fraction(EF), which can be easily measured from an M-mode echocardiogram. However, these M-mode measurements may be inaccurate in patients with asymmetrical LV due to myocardial infarction, right ventricular overload or sigmoid septum. Especially in such cases, EF should be measured using two-dimensional echocardiography. Usually, LV volumes and EF are calculated using the disc-summation method through the manual tracing of apical two-chamber and four-chamber echocardiograms. On the other hand, it has been recognized that congestive heart failure may arise in the absence of any systolic dysfunction and CHF due to systolic dysfunction never occurs in the absence of concomitant diastolic dysfunction. Although the analysis of pulsed-Doppler transmitral flow velocity has been most widely used for the noninvasive assessment of LV diastolic function, an increase in left atrial pressure during CHF can pseudonormalize an abnormal flow pattern and mask LV diastolic dysfunction. Recently, we proposed a new index for assessing LV diastolic function, flow propagation velocity, which can be measured with color M-mode Doppler echocardiography and baseline-shift technique. Recent studies have shown that the flow propagation velocity is a unique noninvasive parameter of LV diastolic function which can accurately detect the diastolic impairment in patients with different types of cardiac diseases with various loading conditions.     

Contractile reserve assessed by dobutamine test identifies super-responders to cardiac resynchronization therapy

Introduction

In this study, we sought to determine whether myocardial contractile reserve (CR) assessed by dobutamine stress echocardiography (DSE) can identify patients who experience nearly complete normalization of left ventricular (LV) function after the implantation of a cardiac resynchronization therapy (CRT) pacemaker.

Material and methods

The study group consisted of 55 consecutive patients with non-ischemic dilated cardiomyopathy, LV ejection fraction (LVEF) < 35%, and prolonged QRS complex duration, who were scheduled for CRT pacemaker implantation. The DSE (20 µg/kg/min) was performed in all patients. The CR assessment was based on a change in the wall motion score index (ΔWMSI) and ΔLVEF during DSE. Super-response was defined as an increase in LVEF to > 50% and reduction in left ventricular end-systolic dimension to < 40 mm 12 months following the CRT implantation.

Results

A total of 7 patients (12.7%) were identified as super-responders to CRT. When compared to non-super-responders, these patients had significantly higher values of the dobutamine-induced change in ΔWMSI (1.031 ±0.120 vs. 0.49 ±0.371, p < 0.01), and ΔEF (17.9 ±2.2 vs. 8.8 ±6.2, p < 0.01). Receiver operating characteristic analysis showed that dobutamine-induced changes in ΔWMSI ≥ 0.7 and ≥ 14% for ΔEF are the best discriminators for a super-response. Patients with ΔWMSI ≥ 0.7 and ΔEF ≥ 14% are significantly less often hospitalized (p < 0.01) for worsening of heart failure during 28.5 ±3.0 months of the follow-up.

Conclusions

Contractile reserve assessed by DSE can identify patients with dilated cardiomyopathy who are likely to experience near normalization of LV function following CRT.