Mohammad Saeed

Cardiac Resynchronization Therapy in Patients with Right Ventricular Pacing-Induced Cardiomyopathy

Background: It is not known whether patients with normal baseline left ventricular (LV) function who develop right ventricular (RV) pacing‐induced cardiomyopathy as a result of dual‐chamber pacing can benefit from cardiac resynchronization therapy (CRT). We retrospectively assessed the effect of a CRT upgrade on RV pacing‐induced cardiomyopathy.

Variability in Post‐Pacing Intervals Predicts Global Atrial Activation Pattern During Tachycardia

Introduction: Knowledge of the global atrial activation pattern is critical to ablation of an atrial arrhythmia. We hypothesized that the variability in post‐pacing intervals (PPIs) with pacing at different cycle lengths (CLs) from the same pacing site, regardless of distance to the circuit, can be used to identify atrial activation patterns during tachycardia.

Rationale and design for programming implantable cardioverter–defibrillators in patients with primary prevention indication to prolong time to first shock (PROVIDE) study

AIMS Shock therapy delivery by implantable cardioverter-defibrillators (ICD) can be painful and may have negative psychological consequences. Reducing shock burden for patients with ICDs and cardiac resynchronization therapy defibrillators (CRT-Ds) may have beneficial consequences. This may be achieved by avoiding inappropriate shocks for supraventricular tachycardia (SVT) and by limiting appropriate shocks to only those that are necessary to convert ventricular arrhythmias. METHODS AND RESULTS The programming implantable cardioverter-defibrillators in patients with primary prevention indication to prolong time to first shock study (PROVIDE) is a prospective, randomized, multicentre study that will test the hypothesis that a combination of pre-selected ventricular tachyarrhythmia detection, anti-tachycardia pacing, and SVT discriminator parameters will prolong the time to first shock without increasing arrhythmic syncope in patients receiving ICDs for primary prevention. Patients receiving St Jude Medical ICDs and CRT-Ds for primary prevention will be randomized 1:1 to one of two arrhythmia detection and therapy approaches. The study will enroll and follow 1600 patients for at least 1 year or until 226 first shocks have been documented in the total study population. The primary endpoint of the study is the mean time to first shock and the safety endpoint is the rate of arrhythmic syncope. CONCLUSION The PROVIDE trial is a randomized controlled study, designed to assess if a pre-selected combination of programming parameters can reduce shock burden among patients receiving ICDs/CRT-Ds for primary prevention.

Organized Incessant Atrial Arrhythmias in the Setting of Severe, Isolated Biatrial Scarring

Introduction: Diffuse transmural fibrosis and scarring limited to the area without atrial dilation or significant structural heart or other systemic disease has not been reported. We present three cases of a syndrome characterized by refractory organized atrial arrhythmias, diffuse atrial scarring with electrical silence, and mechanical paralysis in the absence of atrial dilation or any systemic or neurodegenerative disorders.

Variability in Postpacing Intervals Predicts Global Ventricular Activation Pattern during Tachycardia

Introduction: Assessment of ventricular activation pattern is critical to the successful ablation of ventricular tachycardia (VT). We have previously shown that the global atrial activation pattern during tachycardia can be rapidly and accurately assessed by calculating the postpacing interval variability (PPIV); PPIV was minimal in circuitous tachycardias and highly variable in centrifugal tachycardias. In the present study, we use the PPIV to determine the ventricular global activation pattern during VT.

Near-field impedance accurately distinguishes among pericardial, intracavitary, and anterior mediastinal position

Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle.

Accuracy of Voltage Signal Measurement During Radiofrequency Delivery Through the SMARTTOUCH Catheter

Current methods for measuring voltage during radiofrequency (RF) ablation (RFA) necessitate turning off the ablation catheter. If voltage could be accurately read without signal attenuation during RFA, turning off the catheter would be unnecessary, allowing continuous ablation. We evaluated the accuracy of the Thermocool SMARTTOUCH catheter for measuring voltage while RF traverses the catheter.

Cardiac resynchronization therapy may improve symptoms of congestive heart failure in patients without electrical or mechanical dyssynchrony.

AIMS Cardiac resynchronization therapy (CRT) has reportedly not been effective in the absence of electrical or mechanical dyssynchrony. We present six patients with severe left ventricular (LV) dilation, mitral regurgitation (MR), and non-ischaemic cardiomyopathy who underwent CRT. We assessed the effects of CRT on LV ejection fraction (EF), LV dimensions, mitral valve regurgitant fraction (RF), pulmonary arterial pressures (PAP), and serum levels of B-natriuretic peptide (BNP). METHODS AND RESULTS All patients had severe LV dilation (>/=6.8 cm) and no electrical or mechanical dyssynchrony. All patients underwent CRT-D (with defibrillator) without complications. Average echocardiographic follow-up was 4.6 months. Mean LVEF increased significantly from 20.8 +/- 3.4 to 28.3 +/- 2.9% after CRT (P < 0.01). Mean LV end-diastolic dimension decreased significantly from 6.9 +/- 0.15 to 6.45 +/- 0.33 cm after CRT (P = 0.03); mean BNP serum level decreased from 1738 +/- 526 to 1040 +/- 768 pg/mL (P = 0.07). Baseline RF decreased from 45 +/- 12.2 to 20 +/- 10.9% after CRT-D (P = 0.009). Mean PAP decreased from 48.5 +/- 5.8 to 42.6 +/- 5.2 (P = 0.03). In five patients, New York Heart Association class symptoms improved by at least one level. No patients required assist devices or transplantation. One patient was hospitalized during follow-up. CONCLUSION We describe six patients with severe LV dilation without evidence of electrical or mechanical dyssynchrony who improved with CRT, possibly due to improvement in MR.