David McCarty

Impact of segmental left ventricle lead position on cardiac resynchronization therapy outcomes

BACKGROUND The optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricle (LV) lateral or posterolateral wall. However, little is known about the impact of segmental pacing site on outcomes. OBJECTIVE We assessed the impact of segmental LV lead position on CRT outcomes. METHODS Patients (n = 115) undergoing CRT were followed prospectively. Segmental LV lead position along the longitudinal axis (apical, midventricle, or basal) was determined retrospectively by examining coronary sinus (CS) venograms and chest X-rays. The primary outcome was a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. Secondary outcomes included change in New York Heart Association (NYHA) functional class and degree of LV reverse remodeling. RESULTS Patients were divided into two groups based on LV lead position: apical (n = 25) and basal/midventricle (n = 90). The apical group was older (72.9 +/- 8.9 vs. 66.5 +/- 13.3 years; P = .010) and more likely to have ischemic cardiomyopathy (77% vs. 52%, P <.001). During a mean follow-up of 15.1 +/- 9.0 months, event-free survival was significantly lower in the apical group: 52% vs. 79%, hazard ratio [HR] 2.7 (95% confidence interval [CI] 1.5-5.5, P = .006). The adverse impact of apical lead placement remained significant after adjusting for clinical covariates: HR 2.3 (95% CI 1.1-4.8, P = .03). The apical group also experienced less improvement in NYHA functional class and less LV reverse remodeling. CONCLUSIONS Apical LV lead placement is associated with worse CRT outcomes. Preferential positioning of LV leads in the basal/midventricle segments may improve outcomes.

Significance of electrocardiographic right bundle branch block in trained athletes.

We sought to determine the clinical and physiologic significance of electrocardiographic complete right bundle branch block (CRBBB) and incomplete right bundle branch block (IRBBB) in trained athletes. The 12-lead electrocardiographic and echocardiographic data from 510 competitive athletes were analyzed. Compared to the 51 age-, sport type-, and gender-matched athletes with normal 12-lead electrocardiographic QRS complex duration, the 44 athletes with IRBBB (9%) and 13 with CRBBB (3%) had larger right ventricular (RV) dimensions, as measured by the basal RV end-diastolic diameter (CRBBB 43 ± 3 mm, IRBBB 38 ± 6 mm, normal QRS complex 35 ± 4 mm, p <0.001) and RV end-diastolic area (CRBBB 33 ± 5, IRBBB 27 ± 7, and normal QRS complex 23 ± 3 cm(2); p <0.001). Athletes with CRBBB also had a relative reduction in the RV systolic function at rest as assessed by the RV fractional area change and peak systolic tissue velocity. Finally, QRS prolongation was associated with parallel increases in interventricular dyssynchrony (basal RV to basal lateral left ventricular peak systolic tissue velocity time difference: CRBBB 112 ± 15, IRBBB 73 ± 33, normal QRS complex 43 ± 39 ms, p <0.001). Despite these findings, no athlete with CRBBB or IRBBB was found to have pathologic structural cardiac disease. In conclusion, among trained athletes, CRBBB and IRBBB appear to be markers of a structural and physiological cardiac remodeling triad characterized by RV dilation, a relative reduction in the RV systolic function at rest, and interventricular dyssynchrony.

Impact of rapid ventricular pacing during percutaneous balloon aortic valvuloplasty in patients with critical aortic stenosis: Should we be using it?

Background: Rapid ventricular pacing (RP) during percutaneous balloon aortic valvuloplasty (BAV) facilitates balloon positioning by preventing the “watermelon seeding” effect during balloon inflation. The clinical consequences of RP BAV have never been compared with standard BAV in which rapid pacing in not used. We evaluated the immediate results and in‐hospital adverse events of patients with severe aortic stenosis (AS) undergoing BAV with and without RP. Methods: This is a retrospective study of patients with severe AS undergoing retrograde BAV. Patients who underwent BAV with RP were compared to those who did not receive RP during BAV. Procedural outcomes, complications, and in‐hospital adverse events were compared between both groups. Stratified analyses were performed to evaluate RP in pre‐specified subsets for confounding and effect modification. Results: Between January 2005 and December 2008, 111 consecutive patients underwent retrograde BAV at Massachusetts General Hospital. Sixty‐seven patients underwent BAV with RP. Nearly 90% of patients were NYHA class III or IV and the mean AVA was 0.64 cm2. Baseline characteristics and balloon sizes were similar in the two groups. The average post‐BAV AVA was smaller in the RP group compared to the no‐RP group (0.87 v. 1.02 cm2, p = 0.02). Pre and post‐cardiac output, in‐hospital mortality, myocardial infarction, stroke, frequency of cardiopulmonary arrest, vasopressor use, and major complications were similar in the two groups. Conclusions: 1) RP allows precise balloon placement during BAV. 2) RP BAV is associated with lower post‐BAV AVA. 3) RP BAV may be safely performed in patients with high‐risk cardiac features.

Mechanism of Decrease in Mitral Regurgitation After Cardiac Resynchronization Therapy: Optimization of the Force–Balance Relationship

Background—Cardiac resynchronization therapy (CRT) has been shown to reduce functional mitral regurgitation (MR). It has been proposed that the mechanism of MR reduction relates to geometric change or, alternatively, changes in left ventricular (LV) contractile function. Normal mitral valve (MV) function relies on a balance between tethering and closing forces on the MV leaflets. Functional MR results from a derangement of this force–balance relationship, and CRT may be an important modulator of MV function by its ability to enhance the force–balance relationship on the MV. We hypothesized that CRT improves the comprehensive force balance acting on the valve, including favorable changes in both geometry and LV contractile function. Methods and Results—We examined the effect of CRT on 34 patients with functional MR before and after CRT (209±81 days). MR regurgitant volume, closing forces on MV (derived from Doppler transmitral pressure gradients), including dP/dt and a factor (closing pressure ratio) expressing how long the peak closing gradient is maintained over systole (closing pressure ratio=velocity time integral/MR peak velocity×mitral regurgitation time), and dyssynchrony by tissue Doppler were measured. End-diastolic volume, end-systolic volume, mitral valve annular area (MAA) and contraction (percent change in MAA from end-diastole to midsystole), leaflet closing area (leaflet area during valve closure), and tenting volume (volume under leaflets to annular plane) were measured by 3D echocardiography. After CRT, end-diastolic volume (253±111 versus 221±110 mL, P<0.001) and end-systolic volume (206±97 versus 167±91 mL, P<0.001) decreased and ejection fraction (19±6 versus 27±9%, P<0.001) increased. MR regurgitant volume decreased from 35±17 to 23±14 mL (P<0.001), MAA from 11.6±3.5 to 10.5±3.1 cm2 (P<0.001), leaflet closing area from 15.4±5 to 13.7±3.8 cm2 (P<0.001), and tenting volume from 5.7±2.6 to 4.6±2.2 mL (P<0.001). Peak velocity (and therefore transmitral closing pressure) was more sustained throughout systole, as reflected by the increase in the closing pressure ratio (0.77±0.1 versus 0.84±0.1 before CRT versus after CRT, P=0.01); dP/dt also improved after CRT. There was no change in dyssynchrony or MAA contraction. Conclusions—Reduction in MR after CRT is associated with favorable changes in MV geometry and closing forces on the MV. It does so by favorably affecting the force balance acting on the MV in 2 ways: reducing tethering through reversal of LV remodeling and increasing the systolic duration of peak transmitral closing pressures.

Gender effects on cardiac valvular function in hyperprolactinaemic patients receiving cabergoline: a retrospective study

Background  Ergot‐derived dopamine agonists are associated with increased risk of valvular dysfunction in Parkinson’s disease. The risk of valvular disease associated with lower doses of cabergoline used to treat prolactinomas remains controversial.

Interlead Distance and Left Ventricular Lead Electrical Delay Predict Reverse Remodeling During Cardiac Resynchronization Therapy

Background: Both anatomic interlead separation and left ventricle lead electrical delay (LVLED) have been associated with outcomes following cardiac resynchronization therapy (CRT). However, the relationship between interlead distance and electrical delay in predicting CRT outcomes has not been defined.

Comparison of Procedural and In-Hospital Outcomes of Percutaneous Balloon Aortic Valvuloplasty in Patients >80 Years Versus Patients <80 Years

Percutaneous balloon aortic valvuloplasty (PBAV) is a procedure used for palliation, bridging to surgery, and as an integral step in the procedure for percutaneous aortic valve replacement. Older patients with severe aortic stenosis are thought to have greater risk for adverse perioperative events than younger patients. The aim of this study was to evaluate the outcomes of patients aged >80 years and those aged < or =80 years who underwent PBAV to identify factors associated with adverse clinical outcomes. This was a retrospective study of 111 consecutive patients with severe symptomatic aortic stenosis who underwent retrograde PBAV at Massachusetts General Hospital from December 2004 to December 2008. Forty-nine patients (44%) were men, and the mean age for the whole group was 82 +/- 8 years. Patients were divided into 2 age groups: those aged >80 years (n = 73) and those aged < or =80 years (n = 38). Procedural outcomes, complications, and in-hospital adverse events were compared. Multivariate logistic regression was used for the adjusted analysis. Nearly 90% of patients were in New York Heart Association class III or IV. Patients aged >80 years had lower baseline ejection fractions (43.5% vs 56.1%, p <0.01) and smaller aortic valve areas (0.59 vs 0.73 cm(2), p <0.01). Although the 2 age groups had a similar percentage of aortic valve area increase (55.5% vs 45.2%, p = 0.28), those aged >80 years had smaller post-PBAV aortic valve areas (0.89 vs 1.02 cm(2), p <0.05). Overall, in-hospital mortality was 8.1%, with no significant differences between the groups. Advanced age was not an independent predictor of in-hospital death, myocardial infarction, stroke, cardiac arrest, or tamponade; however, patients aged >80 years had a significantly higher incidence of intraprocedural emergent intubation and cardiopulmonary resuscitation compared to the younger group. New York Heart Association class was the only independent predictor of worse in-hospital outcomes. In conclusion, compared to younger patients, those aged >80 years had less favorable preprocedural characteristics for PBAV but similar overall in-hospital clinical outcomes. Patients aged >80 years had significantly higher incidence of emergent intubation and cardiopulmonary resuscitation during PBAV.

Usefulness of Low-Dose Dobutamine Echocardiography to Predict Response and Outcome in Patients Undergoing Cardiac Resynchronization Therapy

A substantial proportion of patients who meet the current guidelines for cardiac resynchronization therapy (CRT) fail to respond to this pacing modality. Although appropriate patient selection and left ventricular (LV) lead location have been ascribed as determinants of CRT response, the interaction among contractile reserve, dynamics of dyssynchrony, and lead location is not well understood. The present study prospectively evaluated the effect of contractile reserve and dobutamine-induced changes in LV synchrony, in relation to the LV lead location, as predictors of the response to CRT. In the present study, 31 patients were prospectively evaluated and underwent low-dose dobutamine echocardiography. The dobutamine-induced increase in ejection fraction (contractile reserve [CR]) was measured, and the most mechanically delayed segment was identified to classify patients into 2 groups. Group 1 had a CR of >20% and a LV lead position concordant with the mechanically delayed segment. Group 2 included the remaining patients (i.e., low CR, discordant LV lead position, or both). Patients in group 1 were significantly more likely to have an echocardiographic response at 6 months (80% of group 1 vs 29% of group 2, p = 0.018) and had an improved 2-year heart failure hospitalization-free survival rate (90% in group 1 vs 33% in group 2, p = 0.006). In conclusion, low-dose dobutamine echocardiography provides information that can help to predict responders to CRT. The response rates and heart failure hospitalization-free survival were improved in those patients with a CR >20% and an LV lead tip concordant with the most delayed mechanical segment.

Absence of left ventricular apical rocking and atrial-ventricular dyssynchrony predicts non-response to cardiac resynchronization therapy

AIMS Current imaging techniques attempt to identify responders to cardiac resynchronization therapy (CRT). However, because CRT response may depend upon several factors, it may be clinically more useful to identify patients for whom CRT would not be beneficial even under optimal conditions. We aimed to determine the negative predictive value of a composite echocardiographic index evaluating atrial-ventricular dyssynchrony (AV-DYS) and intraventricular dyssynchrony. METHODS AND RESULTS Subjects with standard indications for CRT underwent echo before and during the month following device implantation. AV-DYS was defined as a percentage of left ventricular (LV) filling time over the cardiac cycle. AV-DYS, which produces a characteristic rocking of the LV apex, was quantified as the percentage of the cardiac cycle over which tissue Doppler-derived displacement curves of the septal and lateral walls showed discordance. CRT responder status was determined based on the early haemodynamic response to CRT (intra-individual improvement >25% in the Doppler-derived LV dP/dt). Among 40 patients, optimal cut-points predicting CRT response were 31% for LV apical rocking and 39% for AV-DYS. The presence of either apical rocking >31% or AV-DYS ≤ 39% had a sensitivity of 95%, specificity of 80%, positive predictive value of 83%, and a negative predictive value of 94% for CRT response. CONCLUSION After pre-selection of candidates for CRT by QRS duration, application of a simple composite echocardiographic index may exclude patients who would be non-responders to CRT and thus improve the global rate of therapy success.

Growth hormone status predicts left ventricular mass in patients after cure of acromegaly

CONTEXT Growth hormone excess and growth hormone deficiency (GHD) are both associated with increased cardiovascular morbidity. A specific acromegaly-related cardiomyopathy has been described, characterized in part by increased left ventricular mass (LVM). Growth hormone deficiency is associated with reduced LVM. Following cure of acromegaly with surgery or radiation therapy, GHD may develop; however, its effects on cardiac morphology and function in this population are not established. OBJECTIVE We hypothesized that the development of GHD in patients with prior acromegaly would be associated with cardiac morphologic and functional changes that differ from those in patients who are GH sufficient following cure of acromegaly. DESIGN A cross-sectional study was conducted in a Clinical Research Center. Study participants consisted of three groups of subjects (n=34): I. Cured acromegaly with GHD (n=15), II. Cured acromegaly with GH sufficiency (n=8), and III. Active acromegaly (n=11). Main outcome measures included cardiac morphology and function, using echocardiography parameters. RESULTS Mean age and BMI, 44.6 ± 2.3 years (SEM) and 30.7 ± 1.3 kg/m², respectively, were not different among the three groups. Mean peak GH values were: I. 2.8 ± 0.4 ng/ml; II. 30.1 ± 9.1 ng/ml (p=0.0002.) In group I, left ventricular mass, indexed to body surface area (LVMi), was within the normal range in all patients; moreover, left ventricular (LV) geometry was normal. At least 50% of patients in groups II and III had elevated LVMi, and in 50% of patients, LV geometry was abnormal, indicating pathologic hypertrophy. Ejection fraction was similar between all three groups. There were no significant differences in diastolic function. CONCLUSIONS Patients who develop GHD following cure of acromegaly do not demonstrate elevated LV mass, in contrast to patients with a history of acromegaly but normal GH levels or to patients with active acromegaly. This suggests that GH status after treatment of acromegaly correlates with LV mass, and that, in GH sufficient patients, reversal of remodeling may be slower than previously thought. These data suggest that it will be important to determine whether GH replacement alters left ventricular morphology over time.