Improved patient selection for cardiac resynchronization therapy by normalization of QRS duration to left ventricular dimension.

AIMS: This study evaluates the relative importance of two components of QRS prolongation, myocardial conduction velocity and travel distance of the electrical wave front (i.e. path length), for the prediction of acute response to cardiac resynchronization therapy (CRT) in left bundle branch block (LBBB) patients. METHODS AND RESULTS: Thirty-two CRT candidates (ejection fraction <35%, LBBB) underwent cardiac magnetic resonance (CMR) imaging to provide detailed information on left ventricular (LV) dimensions. Left ventricular end-diastolic volume (LVEDV) was used as a primary measure for path length, subsequently QRSd was normalized to LV dimension (i.e. QRSd divided by LVEDV) to adjust for conduction path length. Invasive pressure-volume loop analysis at baseline and during CRT was used to assess acute pump function improvement, expressed as LV stroke work (SW) change. During CRT, SW improved by +38 ± 46% (P < 0.001). The baseline LVEDV was positively related to QRSd (R = 0.36, P = 0.044). Despite this association, a paradoxical inverse relation was found between LVEDV and SW improvement during CRT (R = -0.40; P = 0.025). Baseline unadjusted QRSd was found to be unrelated to SW changes during CRT (R = 0.16; P = 0.383), whereas normalized QRSd (QRSd/LVEDV) yielded a strong correlation with CRT response (R = 0.49; P = 0.005). Other measures of LV dimension, including LV length, LV diameter, and LV end-systolic volume, showed similar relations with normalized QRSd and SW improvement. CONCLUSION: Since normalized QRSd reflects myocardial conduction properties, these findings suggest that myocardial conduction velocity rather than increased path length mainly determines response to CRT. Normalizing QRSd to LV dimension might provide a relatively simple method to improve patient selection for CRT.

The influence of right ventricular stimulation on acute response to cardiac resynchronisation therapy.

BACKGROUND: The contribution of right ventricular (RV) stimulation to cardiac resynchronisation therapy (CRT) remains controversial. RV stimulation might be associated with adverse haemodynamic effects, dependent on intrinsic right bundle branch conduction, presence of scar, RV function and other factors which may partly explain non-response to CRT. This study investigates to what degree RV stimulation modulates response to biventricular (BiV) stimulation in CRT candidates and which baseline factors, assessed by cardiac magnetic resonance imaging, determine this modulation. METHODS AND RESULTS: Forty-one patients (24 (59 %) males, 67 ± 10 years, QRS 153 ± 22 ms, 21 (51 %) ischaemic cardiomyopathy, left ventricular (LV) ejection fraction 25 ± 7 %), who successfully underwent temporary stimulation with pacing leads in the RV apex (RVapex) and left ventricular posterolateral (PL) wall were included. Stroke work, assessed by a conductance catheter, was used to assess acute haemodynamic response during baseline conditions and RVapex, PL (LV) and PL+RVapex (BiV) stimulation. Compared with baseline, stroke work improved similarly during LV and BiV stimulation (∆+ 51 ± 42 % and ∆+ 48 ± 47 %, both p < 0.001), but individual response showed substantial differences between LV and BiV stimulation. Multivariate analysis revealed that RV ejection fraction (ß = 1.01, p = 0.02) was an independent predictor for stroke work response during LV stimulation, but not for BiV stimulation. Other parameters, including atrioventricular delay and scar presence and localisation, did not predict stroke work response in CRT. CONCLUSION: The haemodynamic effect of addition of RVapex stimulation to LV stimulation differs widely among patients receiving CRT. Poor RV function is associated with poor response to LV but not BiV stimulation.

Remote monitoring and follow-up of cardiovascular implantable electronic devices in the Netherlands : An expert consensus report of the Netherlands Society of Cardiology.

Remote monitoring of cardiac implanted electronic devices (CIED: pacemaker, cardiac resynchronisation therapy device and implantable cardioverter defibrillator) has been developed for technical control and follow-up using transtelephonic data transmission. In addition, automatic or patient-triggered alerts are sent to the cardiologist or allied professional who can respond if necessary with various interventions. The advantage of remote monitoring appears obvious in impending CIED failures and suspected symptoms but is less likely in routine follow-up of CIED. For this follow-up the indications, quality of care, cost-effectiveneness and patient satisfaction have to be determined before remote CIED monitoring can be applied in daily practice. Nevertheless remote CIED monitoring is expanding rapidly in the Netherlands without professional agreements about methodology, responsibilities of all the parties involved and that of the device patient, and reimbursement. The purpose of this consensus document on remote CIED monitoring and follow-up is to lay the base for a nationwide, uniform implementation in the Netherlands. This report describes the technical communication, current indications, benefits and limitations of remote CIED monitoring and follow-up, the role of the patient and device manufacturer, and costs and reimbursement. The view of cardiology experts and of other disciplines in conjunction with literature was incorporated in a preliminary series of recommendations. In addition, an overview of the questions related to remote CIED monitoring that need to be answered is given. This consensus document can be used for future guidelines for the Dutch profession.

Patients with coronary stenosis and a fractional flow reserve of ≥0.75 measured in daily practice at the VU University Medical Center.

Objectives. The aim of this study was to analyse the rate of major adverse clinical events in patients with coronary artery disease and a fractional flow reserve (FFR) of ≥0.75 and deferred for coronary intervention in daily practice. Methods. From 1 January to 31 December 2006, FFR measurement was initiated in 122 patients (5%) out of 2444 patients referred for coronary angiography. In two patients FFR measurement failed and in one patient the FFR value could no longer be traced in the documents. Thus, 119 patients (84 men, 64 years, range 41-85) were included in the evaluation (145 lesions). Major adverse clinical events (death, myocardial infarction, percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG)) and the presence of angina were evaluated at follow-up. Furthermore a cost-effectiveness analysis was performed.Results. In 93 patients (76%) the FFR value was ≥0.75. Seventy of these 93 patients (76%) were treated with medication alone or underwent PCI for a different lesion (medical treatment group). Average duration of follow-up of all 119 patients was 22 months (range 4 days to 30 months). In the medical treatment group seven patients (10%) experienced a major adverse clinical event related to the FFR-evaluated lesion during follow-up. In this study population, the use of FFR measurement is cost-reducing provided that at least 65% of the patients in the medical treatment group has had a PCI with stent implantation when the use of FFR measurement is impossible. In this case, the decision to use PCI with stent implantation is purely based on the angiogram. Conclusions. In patients with a coronary stenosis based on visual assessment and an FFR of ≥0.75 deferral of PCI or CABG is safe in daily clinical practice and saves money. (Neth Heart J 2010;18:402-7.).

Fifty years of cardiac pacing: the dark side of the moon?

Fifty years after its introduction, cardiac pacing has evolved from an experimental medical treatment to an expanding field in today's cardiology. Only recently there is accumulating evidence that prolonged stimulation of the right ventricular apex is associated with clinically significant adverse effects. In this commentary, the potential adverse effects are summarised and potential modifications in contemporary pacing are discussed. (Neth Heart J 2008;16(Suppl1):S12-S14.).

Mechanical dyssynchrony by 3D echo correlates with acute haemodynamic response to biventricular pacing in heart failure patients.

AIMS: One-third of dilated cardiomyopathy patients receiving a biventricular pacing-device do not respond to this form of therapy. Therefore, the utility of mechanical dyssynchrony by real-time 3D echocardiography (RT3DE) for predicting systolic response to biventricular pacing, of which maximal rate of pressure rise (dP/dt(max)) served as the gold-standard, was evaluated. METHODS AND RESULTS: Seventeen consecutive heart failure patients (aged 64 +/- 10 years, 8 male, 6 ischaemic cardiomyopathy, mean QRS duration 136 +/- 32 ms) underwent RT3DE and biventricular pacing. Post-processing software provided data of global left ventricular (LV) function and the systolic dyssynchrony index of 17 LV segments (SDI(17), %) for mechanical dyssynchrony. During biventricular pacing, percentual change in dP/dt(max) compared to the non-pacing mode, DeltadP/dt(max) was measured invasively with conductance catheters. LV ejection fraction was 31 +/- 10%, SDI(17) was 10.2 +/- 4.2% and percentual DeltadP/dt(max) during biventricular pacing was 14.5 +/- 12.4. A significant correlation (r = 0.729, P = 0.001) was found between SDI(17) and percentual DeltadP/dt(max), and between QRS duration and percentual DeltadP/dt(max) (r = 0.721, P = 0.001). CONCLUSION: The present study suggests that mechanical dyssynchrony measured by RT3DE shows a good correlation with invasively determined acute haemodynamic response to biventricular pacing in patients with symptomatic dilated cardiomyopathy. Future studies are needed to further define the clinical utility of RT3DE in identifying patients who are most likely to respond to cardiac resynchronization therapy.

Comparison of the haemodynamics of different pacing sites in patients undergoing resynchronisation treatment: need for individualisation of lead localisation.

BACKGROUND: Biventricular pacing is a new therapy for the treatment of heart failure. However, a substantial number of patients do not respond to this therapy. HYPOTHESIS: Individually determined maximal pacing sites will improve the haemodynamic response and increase the number of responders. METHODS: In 48 patients with heart failure, the acute haemodynamic effects of nine different pacing configurations were studied, using two right and left ventricular pacing sites and their combinations. Cardiac index was measured using Doppler echocardiography. For further analysis, the combination with the highest cardiac index improvement was compared with baseline. Moreover, the number of responders was calculated using a cut-off value of 10% increase in cardiac index. RESULTS: The mean (SD) increase in cardiac index ranged between 3.8% (6.0%) and 11.1% (8.6%). The pacing site with maximal cardiac index was highly variable between patients, and here the cardiac index increased to 14.8% (7.6%; (p<0.001). The number of responders varied between 15% and 64%, increasing to 75% at the site with maximal increase in cardiac index. In a subset of patients, the haemodynamic improvement after pacemaker implantation correlated well with the acute haemodynamics. CONCLUSION: Individualisation of pacing configuration for biventricular pacing leads to further haemodynamic improvement in patients with heart failure and reduces the number of patients not responding to this therapy.

Cardiac resynchronization therapy: assessment of dyssynchrony and effects on metabolism.

In recent years cardiac resynchronization therapy has emerged as a promising new treatment strategy in a subgroup of patients with congestive heart failure and an asynchronous contraction pattern. By simultaneously pacing both right ventricular apex and lateral side of the left ventricle, ventricular synchrony can be partially restored and beneficial effects on cardiac performance can be observed. This review discusses the principles of ventricular dyssynchrony, and the acute and chronic effects of cardiac resynchronization therapy on systolic function, cardiac metabolism, and clinical parameters. Furthermore, the issue of identifying patients who do not respond to this therapy is addressed.

Major dissection of the coronary sinus and its tributaries during lead implantation for biventricular stimulation: angiographic follow-up.

Dissection of the coronary sinus during lead implantation for biventricular pacemaker implantation in patients with advanced heart failure is a serious complication that has occasionally been reported. We report on the clinical outcome and angiographic follow-up in a series of 7 patients with acute major dissection from 103 consecutive attempts (incidence 6.8%). Serial echocardiography was performed in all patients and all underwent follow-up angiography 2-3 months after the procedure. In 1 patient, pericardial extravasation was seen during retrograde venography. Clinical follow-up was uneventful except for one other patient who complained of prolonged chest discomfort for several hours after the procedure. In none of the patients were there signs of pericardial effusion or tamponade demonstrated on echocardiography. Venograms during the procedure and after follow-up were analysed using a quantitative coronary angiography system (CAAS II). Parameters included minimal luminal diameter, diameter stenosis, minimal cross-sectional area and an estimation of the reference diameter. There were no significant differences in all analysed parameters, although in 1 patient a small partial dissection was present. Thus, although dissection of the coronary sinus following lead implantation for biventricular stimulation is not an uncommon complication, it is usually well tolerated. Long-term angiographic follow-up demonstrated no significant vessel damage or vessel remodeling.

Recommendations for pacemaker implantation for the treatment of atrial tachyarrhythmias and resynchronisation therapy for heart failure: A report from the task force on pacemaker indications of the Dutch Working Group on Cardiac Pacing.

Today, new pacing algorithms and stimulation methods for the prevention and interruption of atrial tachyarrhythmias can be applied on patients who need bradycardia pacing for conventional reasons. In addition, biventricular pacing as additive treatment for patients with severe congestive heart failure due to ventricular systolic dysfunction and prolonged intraventricular conduction has shown to improve symptoms and reduce hospital admissions. These new pacing technologies and the optimising of the pacing programmes are complex, expensive and time-consuming. Based on many clinical studies the indications for these devices are beginning to emerge. To support the cardiologist's decision-making and to prevent waste of effort and resources, the 'ad hoc committee' has provided preliminary recommendations for implantable devices to treat atrial tachyarrhythmias and to extend the treatment of congestive heart failure respectively.

Comparison of the haemodynamic effects of right ventricular outflow-tract pacing with right ventricular apex pacing: a quantitative review.

The right ventricular apex has been used for cardiac stimulation because this position is easily accessible and is associated with a stable position of the electrode with a low dislodgement rate. This position, however, is associated with a dyssynchronous left ventricular contraction with subsequent deleterious haemodynamic effects. Alternative stimulation sites have been studied extensively because of a potentially better haemodynamic effect compared with right ventricular apex pacing. Using a Cochrane search strategy, nine studies were selected to analyze the haemodynamic effects of right ventricular outflow-tract pacing. The results of these studies (n=217) were pooled and indicated a significantly better haemodynamic effect (odds ratio 0.34, confidence interval 0.15-0.53) compared with right ventricular apex pacing. Therefore, these data suggest that right ventricular outflow-tract pacing may offer a modest but significant benefit over right ventricular apex pacing in patients selected for pacemaker implantation on the basis of symptomatic bradyarrhythmias.

Utility and safety of prolonged temporary transvenous pacing using an active-fixation lead: comparison with a conventional lead.

Transvenous temporary pacing is associated with a substantial dislocation rate reported to range from 10 to 37%. The aim of the study was to assess the safety and utility of a recently introduced 3.5 Fr temporary pacing lead using active fixation in a consecutive series of 36 patients with prolonged (> or = 48 hours) transvenous temporary pacing (validation group). A group of 36 patients with prolonged transvenous pacing managed with a passive-fixation lead just prior to the introduction of the active-fixation lead served as a control group (reference group). Pacing related adverse events included dislocation, inappropriate pacing (i.e., two-fold or greater increase of initial pacing threshold), local infection, and thrombosis. There were no significant differences in patient characteristics or duration of pacing (5.84 +/- 2.4 days in the reference group vs 5.94 +/- 2.6 days in the validation group). Acute pacing threshold was significantly higher in the validation group as compared to the reference group (1.38 +/- 0.67 V vs. 0.7 +/- 0.21 V, P < 0.01). The dislocation rate was significantly lower in the validation group as compared to the reference group (5.5 vs 33.3%, P < 0.001). There were 11 (31%) pacing related adverse events in the validation group versus 21 (58%) in the reference group (P < 0.01). The vast majority of patients in the validation group (75%) had ambulatory temporary pacing. Thus, transvenous temporary pacing using active fixation is safe and is associated with a low dislocation rate and a reduction in pacing related adverse events.

Successful percutaneous extraction of an inadvertently placed left ventricular pacing lead.

A 74-year-old patient was referred for a rapidly increasing pacing threshold 9 months after DDD pacemaker implantation because of symptomatic total atrioventricular (AV) block. She had a history of hypertension, diabetes with micro-angiopathy and a recent transient ischaemic attack. The paced electrocardiogram on admission had a right bundle branch block pattern and 3-dimensional transoesophageal echocardiography demonstrated passage of the lead through an atrial septal defect with a left ventricular position in addition to moderate atherosclerosis of the ascending aorta. No thrombus could be detected on the lead. Percutaneous extraction is usually not recommended because of the risk of mobilization of thrombus material. However, the risk of stroke during removal using cardiopulmonary bypass in this patient was considerably increased because of the presence of multiple independent risk factors. Therefore, percutaneous extraction using a locking device was selected and performed without complications: follow-up was uneventful.

Corrected TIMI frame count and frame count velocity.

BACKGROUND: Little is known about the differences between the corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) and the 'frame count velocity' (FCV), an estimate of blood flow velocity derived from the TFC and the length of the related vessel, in each of the three epicardial coronary arteries. METHODS: After angioplasty of 119 coronary vessels, 50 left anterior descending (LAD), 27 left circumflex (LCX) and 42 right coronary arteries (RCA), the CTFC was compared with the FCV assessed by measuring the length of the coronary arteries with an intracoronary guidewire. RESULTS: The three vessels show a significant difference in mean length (the LAD was 14.5±1.6 cm, LCX 12.8±1.9 cm and RCA 11.3±1.4 cm, p<0.001 for all comparisons), making it possible to convert the TFC to the FCV with reasonable accuracy without having to use a guidewire. The mean length of the LCX and the RCA was found to be considerably longer than in previous reports on which the CTFC is based. In addition, with this method the estimation of the coronary blood flow velocity in the RCA is significantly higher compared with the LAD and LCX (23.0±7.9 cm/sec versus 17.6±7.4 cm/sec and 16.4±6.3 cm/sec, respectively, p<0.001). CONCLUSION: With the TFC and the average length of the related coronary artery presented in this study, the FCV can be calculated for each of the three vessels resulting in a simple and, compared with the CTFC, more accurate angiographic estimation of the coronary blood flow velocity.

Predictive value of markers of myocardial reperfusion in acute myocardial infarction for follow-up left ventricular function.

This study evaluated recently suggested invasive and noninvasive parameters of myocardial reperfusion after acute myocardial infarction (AMI), assessing their predictive value for left ventricular function 4 weeks after AMI and reperfusion defined by myocardial contrast echocardiography (MCE). In 38 patients, angiographic myocardial blush grade, corrected Thrombolysis In Myocardial Infarction frame count, ST-segment elevation index, and coronary flow reserve (n = 25) were determined immediately after primary percutaneous transluminal coronary angioplasty (PTCA) for first AMI, and intravenous MCE was determined before, and at 1 and 24 hours after PTCA to evaluate myocardial reperfusion. Results were related to global wall motion index (GWMI) at 4 weeks. MCE 1 hour after PTCA showed good correlation with GWMI at 4 weeks (r = 0.684, p <0.001) and was in an analysis of variance the best parameter to predict GWMI 4 weeks after AMI. The ST-segment elevation index was close in its predictive value. Considering only invasive parameters of reperfusion myocardial blush grade was the best predictor of GWMI at 4 weeks (R(2) = 0.3107, p <0.001). A MCE perfusion defect size at 24 hours of > or =50% of the MCE perfusion defect size before PTCA was used to define myocardial nonreperfusion. In a multivariate analysis, low myocardial blush grade class was the best predictor of nonreperfusion defined by MCE. Thus, intravenous MCE allows better prediction of left ventricular function 4 weeks after AMI than other evaluated parameters of myocardial reperfusion. Myocardial blush grade is the best predictor of nonreperfusion defined by MCE and is the invasive parameter with the greatest predictive value for left ventricular function after AMI. Coronary flow parameters are less predictive.

Clinical relevance of loss of atrial sensing in patients with single lead VDD pacemakers.

During single lead VDD pacing, loss of atrial sensing is reported to be 2%-11% of patients in the literature. The impact on quality-of-life and exercise duration has never been established. This study tried to assess the clinical relevance of loss of atrial sensing in patients with single lead VDD pacemakers. Twenty-one patients with total AV block were studied 3 months after single lead VDD pacemaker implantation. During a 6-minute walk test, atrial undersensing was verified and adjusted to achieve undersensing in < 5% (group 1), 5%-10% (group 2), and > 10% (group 3). Patients were allocated to each group in a randomized double blind crossover design. At the end of each 2-month study period all patients underwent symptom limited treadmill exercise testing. Subjective assessment of exercise difficulty was made using the Borg score, and quality-of-life assessment was performed using the Health Status Questionnaire. Exercise duration significantly decreased in group 3 (228 +/- 50 s) as compared to group 1 (257 +/- 42 s) and group 2 (250 +/- 46 sec) with an increase in the Borg score. Quality-of-life was decreased for three subscales in group 3 as compared to group 1 and group 2. In conclusion, atrial undersensing of > 10% in patients with single lead VDD pacing was associated with a decrease in exercise duration and increase in the subjective severity score, in addition to a decrease in quality-of-life. Atrial undersensing of < 10% did not effect exercise test results or quality-of-life. Since all studies reported intact atrioventricular synchrony in > or = 90% of patients, loss of atrial sensing is of limited clinical importance in these patients.