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Jagmeet P Singh

Publications and source records attributed to Jagmeet P Singh.

13 recordsLinked to original sources
PubMed2006

Left ventricular lead electrical delay predicts response to cardiac resynchronization therapy.

BACKGROUND: Intracardiac electrograms can be used to guide left ventricular (LV) lead placement during implantation of cardiac resynchronization therapy (CRT) devices. Although attempts often are made to ensure that the LV lead is positioned at a site of maximal electrical delay, information on whether this is useful in predicting the acute hemodynamic response and long-term clinical outcome to CRT is limited. OBJECTIVES: The purpose of this study was to assess the ability of intracardiac (electrogram) measurements made during LV lead placement in patients undergoing CRT for predicting acute hemodynamic response and long-term clinical outcome to CRT. METHODS: Seventy-one subjects with standard indications for CRT underwent electrogram measurements and echocardiograms performed in the acute phase of this study. The LV lead electrical delay was measured intraoperatively from the onset of the surface ECG QRS complex to the onset of the sensed electrogram on the LV lead, as a percentage of the baseline QRS interval. Echocardiographic assessment of the hemodynamic response to CRT was measured as an intra-individual percentage change in dP/dt over baseline (DeltadP/dt, derived from the mitral regurgitation Doppler profile) with CRT on and off. dP/dt was measurable in 48 subjects, and acute responders to CRT were defined as those with DeltadP/dt >or=25%. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to the primary endpoint was estimated by the Kaplan-Meier method, with comparisons made using the log rank test. RESULTS: LV lead electrical delay correlated weakly with DeltadP/dt of the combined group (n = 48, r = 0.311, P = .029) but was strongly correlated with DeltadP/dt in the nonischemic subgroup (n = 20, r = 0.48, P = .027). LV lead electrical delay (%) was significantly longer in acute responders (69.6 +/- 23.9 vs 31.95 +/- 11.57, P = .002) among patients with nonischemic cardiomyopathy. A reduced LV lead electrical delay (<50% of the QRS duration) was associated with worse clinical outcome within the entire cohort (hazard ratio: 2.7, 95% confidence interval: 1.17-6.68, P = .032) as well as when stratified into ischemic and nonischemic subgroups. CONCLUSION: Measuring LV lead electrical delay is useful during CRT device implantation because it may help predict hemodynamic response and long-term clinical outcome.

Aged↗
PubMed2006

Usefulness of a novel "response score" to predict hemodynamic and clinical outcome from cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is an important treatment for patients with congestive heart failure and ventricular dyssynchrony, but response to CRT is highly variable. We assessed whether a scoring system that encompasses a combination of patient selection and procedural variables would improve prediction of CRT response. Thirty-nine patients who underwent CRT with echocardiographic assessment of baseline contractility and left ventricular (LV) dyssynchrony, intraprocedural assessment of LV lead electrical delay, and postprocedural chest radiography were included. Baseline LV dyssynchrony was measured by Doppler tissue velocity imaging as the maximum time difference between peak systolic velocity of anterior, lateral, posterior, and septal walls. The hemodynamic effect of CRT was measured by Doppler analysis of mitral regurgitation as percent change in maximal +dP/dt (DeltadP/dt) with CRT on versus off. Acute responders to CRT were defined as Deltadp/dt >or=25%. Clinical response was measured as a combined end point of hospitalization for heart failure and all-cause mortality. A 4-point response score was generated using variables associated with DeltadP/dt and assigning 1 point for a dorsoventral LV/right ventricular interlead distance>10 cm, 1 point for a LV lead electrical delay>or=50%, 1 point for a baseline maximum +dP/dt <600 mm Hg/s, and 1 point for a maximum time difference>100 ms. In conclusion, there was a significant association between response score (0 to 4 points) and acute hemodynamic response to CRT (p<0.0001). Kaplan-Meier analysis associated a higher response score with improved 12-month event-free survival after CRT implantation (p=0.0019).

Aged↗
PubMed2006

Left ventricular lead proximity to an akinetic segment and impact on outcome of cardiac resynchronization therapy.

BACKGROUND: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. METHODS AND RESULTS: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%DeltadP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %DeltadP/dt 48.8 +/- 67.4% vs group 2 [n = 24]; %DeltadP/dt 32.2 +/- 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %DeltadP/dt 45.7 +/- 50.7% and ML, %DeltadP/dt 45.1 +/- 58.8% vs AL, %DeltadP/dt 2.9 +/- 30.9%, respectively, P = 0.014). CONCLUSION: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT.

Aged↗
PubMed2005

Factors influencing appropriate firing of the implanted defibrillator for ventricular tachycardia/fibrillation: findings from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II).

OBJECTIVES: The purpose of this study was to prospectively examine the role of clinical, laboratory, echocardiographic, and electrophysiological variables as predictors of appropriate initial implantable cardioverter-defibrillator (ICD) therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF) or death in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) population. BACKGROUND: There is limited information regarding the determinants of appropriate ICD therapy in patients with reduced ventricular function after a myocardial infarction. METHODS: We used secondary analysis in one arm of a multicenter randomized clinical trial in patients with a previous myocardial infarction and reduced left ventricular function. RESULTS: We analyzed baseline and follow-up data on 719 patients enrolled in the ICD arm of the MADIT-II study. Appropriate ICD therapy was observed in 169 subjects. Clinical, laboratory, echocardiographic, and electrophysiological variables, along with measures of clinical instability such as interim hospitalization for congestive heart failure (IH-CHF) and interim hospitalization for coronary events (IH-CE), were examined with proportional hazards models and Kaplan-Meier time-to-event curves before and after first interim hospitalization. Interim hospitalization-CHF, IH-CE, no beta-blockers, digitalis use, blood urea nitrogen (BUN) >25, body mass index (BMI) > or =30 kg/m2, and New York Heart Association functional class >II were associated with increased risk for appropriate ICD therapy for VT, VF, or death. In a multivariate (stepwise selection) analysis, IH-CHF was associated with an increased risk for the end point of either VT or VF (hazard ratio [HR] 2.52, 95% confidence interval [CI] 1.69 to 3.74, p < 0.001) and for the combined end point of VT, VF, or death (HR 2.97, 95% CI 2.15 to 4.09, p < 0.001). Interim hospitalization-CE was associated with an increased risk for VT, VF, or death (HR 1.66, 95% CI 1.09 to 2.52, p = 0.02). CONCLUSIONS: These results provide important mechanistic information, suggesting that worsening clinical condition and cardiac instability, as reflected by an IH-CHF or IH-CE, are subsequently associated with a significant increase in the risk for appropriate ICD therapy (for VT/VF) and death.

Aged↗
PubMed2005

Radiographic left ventricular-right ventricular interlead distance predicts the acute hemodynamic response to cardiac resynchronization therapy.

Placement of left ventricular (LV) and right ventricular (RV) leads with maximal interlead separation is frequently sought during cardiac resynchronization therapy (CRT), but few published data are available to support this. This study examined the relation between LV and RV lead separation and the acute effects of CRT on cardiac contractility. A total of 51 consecutive patients who underwent CRT for standard indications with sufficient mitral regurgitation for echocardiographic assessment of contractility (using Doppler profiles of mitral regurgitation as a percentage of change in dP/dt [DeltadP/dt] with CRT on and off), successful transvenous LV lead placement, and postprocedural chest radiography were evaluated. The separation of the LV and RV lead tips (direct interlead distance and horizontal and vertical components) was determined on postprocedural posteroanterior and lateral radiographs. The corrected direct LV-RV interlead distance on the lateral radiograph was correlated with the DeltadP/dt (n = 51, r = 0.43, p = 0.002). The lateral interlead distance in the horizontal plane (r = 0.58, p <0.0001), but not the vertical plane (r = -0.28, p = NS), correlated with the DeltadP/dt. The corrected horizontal interlead distance on the lateral film was greater in acute hemodynamic responders to CRT (DeltadP/dt >25%) compared with nonresponders (14.4 +/- 5.4 vs 9.2 +/- 5.8 cm, p = 0.002). Other LV-RV measures on the posteroanterior and lateral radiographs did not correlate with the DeltadP/dt. Use of these findings may help to guide the sites of LV and RV lead placement to maximize the benefit derived from CRT.

Aged↗
PubMed2005

The coronary venous anatomy: a segmental approach to aid cardiac resynchronization therapy.

The coronary sinus is the gateway for left ventricular (LV) epicardial lead placement for cardiac resynchronization therapy. The implanting electrophysiologist is usually challenged by a high degree of variability in the coronary venous anatomy, making it important to have a more consistent and uniform segmental approach to describe the coronary venous tree and its branches. Classifying the coronary sinus branches and tributaries by the segment of their location rather than by conventional anatomic names (i.e., middle cardiac vein, great cardiac vein, and so on), would provide more relevant anatomic and functional information at the time of LV lead placement. This would enable the implanting physician to proactively correlate the venous anatomy with the segmental wall motion abnormalities or dyssynchrony, as defined by echocardiography and other imaging modalities. The current viewpoint calls for a more systematic segmental approach for describing the coronary venous anatomy.

Cardiac Pacing, Artificial↗
PubMed2005

Depression as a predictor for appropriate shocks among patients with implantable cardioverter-defibrillators: results from the Triggers of Ventricular Arrhythmias (TOVA) study.

OBJECTIVES: We sought to examine the relationship between symptoms of depression and shock-treated ventricular arrhythmias among implantable cardioverter-defibrillator (ICD) patients. BACKGROUND: Depression predicts mortality in patients with coronary artery disease (CAD), but whether this is via an increased risk of fatal ventricular arrhythmias is unclear. METHODS: We prospectively analyzed data on symptoms of depression and risk of ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation [VT/VF]) resulting in ICD discharge in the Triggers of Ventricular Arrhythmias (TOVA) study. Symptoms were assessed by the Center for Epidemiologic Studies-Depression (CES-D) scale. Scores of 16 to 26 and > or =27 represented mild and moderate/severe depression, respectively. The Cox and Anderson-Gill proportional hazards models were used to test for associations among all patients and patients with CAD. RESULTS: Among 645 patients with baseline assessments, 90 (14%) were mildly depressed and 25 (3.9%) were moderately to severely depressed. Moderate/severe depression was associated with time to first shock for VT/VF (hazard ratio [HR] 3.2, 95% confidence interval [CI] 1.1 to 9.9) and all shocks for VT/VF including recurrent episodes (HR 3.2, 95% CI 1.2 to 8.6). Among the 476 CAD patients, the association with time to first shock (HR 6.4, 95% CI 1.9 to 21.1) and all shocks (HR 8.3, 95% CI 2.9 to 23.3) remained. The risk of shock for VT/VF was associated with depression severity in the total population (p for trend = 0.02) and among patients with CAD (p < 0.01), even after controlling for multiple confounders. CONCLUSIONS: More severe symptoms of depression predict shocks for VT/VF among ICD patients. The elevated risk of VT/VF among patients with CAD and depression suggests that arrhythmia may contribute significantly to total mortality in this subgroup.

Cohort Studies↗
PubMed2005

Cardiac resynchronization therapy: the MGH experience.

Cardiac resynchronization therapy (CRT) has gained acceptance as a useful form of device therapy for patients with refractory congestive heart failure. Despite recent technical advances, a significant number of patients continue to remain unresponsive to this form of therapy. This article provides an overview of CRT, highlights several unresolved issues and describes ongoing research efforts to address some of these important questions.

Heart Failure↗
PubMed2004

Catheter ablation of atrial flutter after orthotopic heart transplantation.

INTRODUCTION: Atrial arrhythmias, including atrial flutter, are common in orthotopic heart transplant recipients. However, only a small number of individual case reports describe the electrical circuit and catheter ablation of atrial flutter after heart transplantation. METHODS AND RESULTS: Detailed electrophysiologic evaluation and radiofrequency ablation of atrial flutter were performed in three patients after orthotopic heart transplantation. All cases involved a counterclockwise flutter circuit around the tricuspid annulus. All were successfully ablated at the isthmus between the tricuspid valve and the atrial anastomosis adjacent to the inferior vena cava. CONCLUSION: Atrial flutter involving a counterclockwise circuit around the tricuspid annulus is common in the heart transplant population. Based on the patients described in this study and other cases reported in the literature, this arrhythmia often is treated successfully by ablation of the isthmus between the tricuspid valve and the atrial anastomosis near the inferior vena cava.

Adult↗
PubMed2004

Is baseline autonomic tone associated with new onset atrial fibrillation?: Insights from the framingham heart study.

BACKGROUND: Recent reports have indicated that autonomic tone fluctuations measured by heart rate variability (HRV) precede episodes of paroxysmal atrial fibrillation (AF). Little is known about the impact of baseline autonomic tone and the development of new onset AF in a population-based cohort. The purpose of this study was to assess the role of HRV as a predictor of new onset AF. METHOD: Ambulatory ECG recordings obtained from the Framingham Heart Study subjects attending a routine examination were processed for HRV. The HRV variables analyzed included standard deviation of normal R-R intervals (SDNN), low frequency power (LF), high frequency power (HF), and LF/HF ratio. There were 1434 women and 1142 men (54 +/- 14.1 years) eligible for the study. RESULTS: In 12 years of follow-up, 65 women and 67 men had new onset AF. The study had 80% power to detect a hazard ratio (HR) of 1.3 per standard deviation (SD) decrement in HRV. A one SD decrement in log LF/HF was associated with increased risk of developing AF (HR = 1.23; 95% confidence intervals (CI) = 1.06-1.44) in age- and sex-adjusted models; the association was no longer significant (HR = 1.15; 95% CI = 0.98-1.35) after adjusting for potential confounders. CONCLUSION: Autonomic dysregulation at baseline, as reflected by an altered HRV is associated with risk of AF; however, this association does not persist after adjusting for potential confounders. Much of the apparent association between HRV and AF is mediated by traditional risk factors.

Adult↗
PubMed2002

Genome scan linkage results for heart rate variability (the Framingham Heart Study).

There is a substantial heritable component to the beat-to-beat variation in heart rate. However, the molecular mechanisms underlying the control of heart rate variability (HRV) remain unknown. The present study sought to identify chromosomal regions linked to HRV phenotypes. The first 2 hours of ambulatory electrocardiographic recordings obtained from Framingham Heart Study subjects attending a routine examination were processed for HRV. HRV variables analyzed included very-low-frequency power, low-frequency power, and high-frequency power. Gender-specific residuals were used for log-transformed HRV data after adjustment for age, HR, systolic and diastolic blood pressures, and coffee and alcohol consumption. In conjunction with a 10-cM genome-wide scan, HRV data were available for 725 subjects in 230 extended families, including 390 sibling pairs. Variance component log-of-the-odds (LOD) scores were obtained. The highest multipoint LOD scores were obtained for log very-low frequency on chromosome 15 at 62 cM (LOD 1.84) and for log low frequency on chromosome 2 at 153 cM (LOD 1.81). These data suggest there may be influential genetic regions contributing to HRV. Further studies are warranted to identify genes in these regions that may influence autonomic tone. Recognition of the genetic determinants of HRV may provide additional insights into the pathophysiology of the autonomic nervous system and offer clues to its modulation.

Adult↗