Effects of dual-chamber pacing on regional myocardial deformation in patients with hypertrophic obstructive cardiomyopathy

Right ventricular pacing for hypertrophic obstructive cardiomyopathy: meta-analysis and meta-regression of clinical trials

Aims

Right ventricular pacing for left ventricular outflow tract gradient reduction in hypertrophic obstructive cardiomyopathy remains controversial. We undertook a meta-analysis for echocardiographic and functional outcomes.

Methods and results

Thirty-four studies comprising 1135 patients met eligibility criteria. In the four blinded randomized controlled trials (RCTs), pacing reduced gradient by 35% [95% confidence interval (CI) 23.2–46.9, P < 0.0001], but there was only a trend towards improved New York Heart Association (NYHA) class [odds ratio (OR) 1.82, CI 0.96–3.44; P = 0.066]. The unblinded observational studies reported a 54.3% (CI 44.1–64.6, P < 0.0001) reduction in gradient, which was a 18.6% greater reduction than the RCTs (P = 0.0351 for difference between study designs). Observational studies reported an effect on unblinded NYHA class at an OR of 8.39 (CI 4.39–16.04, P < 0.0001), 450% larger than the OR in RCTs (P = 0.0042 for difference between study designs). Across all studies, the gradient progressively decreased at longer follow durations, by 5.2% per month (CI 2.5–7.9, P = 0.0001).

Conclusion

Right ventricular pacing reduces gradient in blinded RCTs. There is a non-significant trend to reduction in NYHA class. The bias in assessment of NYHA class in observational studies appears to be more than twice as large as any genuine treatment effect.

Echocardiographic tissue imaging evaluation of myocardial characteristics and function in cardiomyopathies

Current echocardiography techniques have allowed more precise assessment of cardiac structure and function of the several types of cardiomyopathies. Parameters derived from echocardiographic tissue imaging (ETI)-tissue Doppler, strain, strain rate, and others-are extensively used to provide a framework in the evaluation and management of cardiomyopathies. Generally, myocardial function assessed by ETI is depressed in all types of cardiomyopathies, non-ischemic dilated cardiomyopathy (DCM) in particular. In hypertrophic cardiomyopathy (HCM), ETI is useful to identify subclinical disease in family members of HCM, to differentiate HCM from other conditions causing cardiac hypertrophy and to predict cardiac events. ETI also for HCM allows addressing the mechanism behind left ventricular outflow tract obstruction and its improvement after therapeutic options. ETI provides cardiac amyloidosis with unique and specific findings such as "apical sparing." Nevertheless, ETI does not seem to provide as much information amenable to histological findings as recently emerging techniques of cardiac magnetic resonance imaging. This review introduces usefulness of ETI and some other ultrasound techniques for detecting clinical and subclinical characteristics of cardiomyopathies, focusing on DCM, HCM, and cardiac amyloidosis.

Relationship between regional and global left ventricular systolic and diastolic function in patients with coronary artery disease assessed by strain rate imaging

BACKGROUND

The relationship between regional and global left ventricular function has not been evaluated. The present study aimed to assess whether regional myocardial contraction and relaxation reflect global left ventricular systolic and early diastolic function, respectively.

METHODS AND RESULTS

The study involved 45 patients with coronary artery disease (CAD). Conventional echocardiography was performed, and segmental peak strain rate (SR) in the systole (S(SR)) and early diastole (E(SR)) were obtained from tissue Doppler imaging in each of 18 segments of the left ventricular myocardium from the apical views. The E(SR) was significantly correlated with S(SR) in all studied segments (r=0.55, p<0.0001). The average values of SR indices in each patient were defined as S(SR) index and E(SR) index, which were derived by dividing the summed value of the S(SR) or E(SR) by the number of respective assessable segments. A significant positive relationship was observed between the S(SR) index and left ventricular ejection fraction (r=0.85, p<0.0001). Also, there was a positive correlation between the E(SR) index and mitral flow E (r=0.68, p<0.0001).

CONCLUSIONS

Regional myocardial contraction and relaxation, as assessed by SR imaging, were closely related in patients with CAD. Furthermore, regional myocardial contraction and relaxation are important factors affecting global left ventricular systolic and early diastolic function.

Augmentation of left ventricular apical endocardial rotation with inotropic stimulation contributes to increased left ventricular torsion and radial strain in normal subjects: quantitative assessment utilizing a novel automated tissue tracking technique

BACKGROUND

The difference in the left ventricular (LV) torsion of the endo- and epicardium (Endo, Epi) with inotropic stimulation and its relation to radial strain (RS) remain unclear.

METHODS AND RESULTS

LV basal and apical short-axis images were recorded in 13 normal subjects at rest and during dobutamine infusion (5, 10 microg x kg (-1) x min(-1)). A total of 8 points (anterior, lateral, posterior and septum in both Endo and Epi) were manually placed by 2-dimensional tissue tracking technique and the movement of these points during a cardiac cycle was tracked, after which the rotation angles and RS were calculated. LV torsion was defined as the net difference between the basal and apical rotations. In the LV apex, Endo-rotation increased (7.8+/-2.7 to 14.1+/-4.6 degrees, p<0.01), whereas Epi-rotation was unchanged, with dobutamine. The apical Endo-rotation was significantly greater than the Epi-rotation, although no difference was seen between the Endo and Epi in the LV base throughout the study. During dobutamine infusion, the LV Endo-torsion increased (9.5+/-2.8 to 19.3+/-4.8 degrees, p<0.01) and these values were greater than those for Epi. The apical RS increased with the dobutamine dose (39.0+/-9.3 to 61.9+/-15.5%, p<0.01), whereas basal RS initially increased at 5 microg x kg(-1) x min(-1), but thereafter showed no further increase at 10 microg x kg(-1) x min(-1) of dobutamine.

CONCLUSIONS

Augmentation of LV rotation with inotropism was clearly observed in the apical Endo, thus causing increased LV endo-torsion and apical RS.

Impact of Ethanol Dosing on the Long-Term Outcome of Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy A Single-Center, Prospective, and Randomized Study

BACKGROUND

The impact of ethanol dose on the long-term outcome of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy was investigated.

METHODS AND RESULTS

Fifty-four patients (age 24-82 years; 65% women) undergoing ASA were randomized into 2 groups according to the dose of injected ethanol: Group A 1-2 ml, Group B >2 ml. Clinical and echocardiographic data were obtained at baseline and during follow-up. The volume of ethanol injected was 1.50+/-0.4 and 2.60+/-0.6 ml (p<0.001) with a subsequent peak of creatine kinase-MB of 2.25+/-1.00 and 2.62+/-1.57 microkat/L (p=0.02) in Groups A and B, respectively. The median follow-up was 39 (range 6-72) months after ASA, during which 1 patient died and 1 repeat procedure was necessary in both groups of patients. Both groups had a significant and similar improvement in outflow pressure gradient, dyspnea (New York Heart Association functional class) and angina pectoris (Canadian Cardiovascular Society class) (p<0.001). There was a significant decrease in the left ventricular ejection fraction (LVEF) in Group B (81+/-7 vs 75+/-7%; p=0.002), but not in Group A (80+/-7 vs 79+/-7%; p=0.67). Thinning of the basal septum was more pronounced in Group B than in Group A (9.3+/-5.7 vs 6.6+/-3.4 mm; p=0.04).

CONCLUSIONS

A lower dose of ethanol injected into the target septal branch reduces both the size of necrosis and subsequent thinning of the basal septum, and preserves LVEF during long-term follow-up. Moreover, the low dose (1-2 ml) is as safe and as hemodynamically efficacious as higher doses.

Age-Related Hemodynamic and Morphologic Differences in Patients Undergoing Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Alcohol septal ablation (ASA) decreases the left ventricular (LV) outflow gradient and relieves symptoms in patients with highly symptomatic hypertrophic obstructive cardiomyopathy (HOCM). The aim of this study was to evaluate the early course of hemodynamic, morphologic and clinical changes in younger and elderly patients.

METHODS AND RESULTS

Forty-four consecutive patients (age, 24-81 years) underwent the ASA procedure for HOCM. Clinical and echocardiographic data were obtained at baseline and periodically up to 12 months after ASA. There was a significant correlation between septum thickness and age at baseline and in the early post procedural period (p = 0.004 at baseline, p = 0.0033 days postoperative, p = 0.0193 weeks pos operative). The dependence of septal thickness on the duration of follow-up (p < 0.001) was significantly influenced by age (p = 0.026), which retained statistical significance after multivariate adjustment (p = 0.031). A decrease in the gradient of the LV outflow was identified in all age-related groups of patients (p < 0.001). After multivariate adjustment, there was a significant influence of age (p = 0.003) and creatine kinase-MB peak (p = 0.016) on the course of outflow gradient reduction.

CONCLUSIONS

ASA is an effective treatment option for patients with HOCM, irrespective of their age. Younger patients are characterized by a thicker basal septum at baseline and a slower hemodynamic improvement within the early post procedural period.