Observational Study Lends Support to CRT Guidelines Reply

A large observational study published in JAMA suggests that patients with left bundle-branch block (LBBB) and longer QRS duration derive the most benefit from a cardiac resynchronization therapy defibrillator (CRT-D). The findings appear to support current, but often criticized, guidelines from the American College of Cardiology, American Heart Association, and the Heart Rhythm Society, in which a class I recommendation is restricted to patients with LBBB and QRS duration of 150 ms or greater.

Click here to read the full post on Forbes.




Bruise Control: Continued Warfarin Beats Heparin Bridging During Device Implantation 1

Many patients receiving an ICD or a pacemaker are already receiving oral anticoagulants. Current guidelines recommend replacement of the oral anticoagulant with the temporary use of heparin as a bridging strategy. Now a new study, BRUISE CONTROL (Bridge or Continue Coumadin for Device Surgery Randomized Controlled Trial), offers convincing evidence that this strategy is not beneficial and, in fact, results in an increase in device-pocket hematoma. Results of the trial were presented today at the Heart Rhythm Society meeting in Denver and published simultaneously in the New England Journal of Medicine.

A group of mostly Canadian investigators randomized 681 patients undergoing ICD or pacemaker implantation with an annual risk for thromboembolic events greater than 5% to either heparin bridging or continued warfarin. The trial was terminated early after a prespecified interim analysis by the data and safety monitoring board. The primary outcome — clinically significant device-pocket hematoma, which the investigators defined as a hematoma that led to prolonged hospitalization, interruption of anticoagulation, or hematoma evacuation — was significantly reduced in the continued-warfarin group, as were all three components of the endpoint:

Primary outcome: 3.5% with continued warfarin versus 16% with heparin bridging (RR 0.19, CI 0.10-0.36, p<0.001).

Click here to read the full story on Forbes.


FDA Approves Second Generation MRI-Friendly Pacemaker System Reply

Medtronic announced today that the FDA had approved its Advisa DR MRI SureScan, a next generation pacemaker system specifically designed and tested for use with MRI scanners. The system, which Medtronic said would be launched immediately, includes the Advisa MRI device and two CapSureFix MRI SureScan leads.

 Click here to read the full post on Forbes.

Medtronic Advisa

BLOCK HF: A “Game Changer” For Cardiac Pacing 3

Editor’s Note: The following guest post is published with the permission of its author,  Edward J. Schloss, MD, (Twitter ID @EJSMD) the medical director of cardiac electrophysiology at Christ Hospital in Cincinnati, OH. Dr. Schloss was an investigator in the BLOCK HF trial.

In what has been described as a “game changer” for the field of cardiac pacing, the BLOCK HF trial was reported at today’s AHA Scientific Sessions showing benefit of biventricular pacing over conventional RV pacing in patients with AV block and LV dysfunction.

Since the development of pacemakers over 50 years ago, doctors have treated patients with AV block with right ventricular pacing. Until about 10 years ago, this was felt to be harmless and potentially beneficial.  Pacing algorithms were designed to force right ventricular pacing and create what was termed a “physiologic AV delay” in the hopes that controlling the timing of atrial and ventricular contraction would improve hemodynamics.

The DAVID trial, reported in 2003, turned the conventional wisdom upside-down, and first clearly showed the hazards of unnecessary RV pacing.  DAVID was designed with the hypothesis that dual chamber pacing in patients receiving ICDs without bradycardia indications would result in improved hemodynamics and therefore improved outcomes as compared to conventional backup ventricular pacing.  To the surprise of the investigators, the opposite proved true.  The group receiving dual chamber pacing had about a 40% increase in mortality and heart failure hospitalization as compared to the minimal pacing group over one year.  As this data was confirmed with additional trials, doctors moved to minimize right ventricular pacing in their patients and new minimal pacing algorithms were developed by industry.

Paralleling the movement to minimize right ventricular pacing, the technique of cardiac resynchronization therapy (CRT) for treatment of heart failure took off.  Here the benefit of pacing right and left ventricles together was established for patients with heart failure and evidence of dyssnchronous ventricular contraction.

The BLOCK HF trial was planned to test the hypothesis that biventricular pacing would be superior to right ventricular pacing in patients with left ventricular dysfunction and heart block requiring pacing.  Enrollment began in December 2003.

BLOCK HF enrolled patients indicated for ventricular pacing due to AV block who had at least mild LV dysfunction (LVEF <50% on optimal HF medical therapy) and NYHA functional class I-III.  All patients then received biventricular devices (pacer or ICD depending on clinical indication) and then were randomized in blinded fashion to conventional dual chamber (RA-RV) pacing vs. biventricular (RA-RV&LV) pacing.  Primary endpoint was the time to first event: total mortality, heart failure exacerbation requiring acute care or >= 15% increase in echocardiographic left ventricular end-systolic volume.

Enrollment and follow up continued with serial echoes and clinical assessments for over seven years with mean follow up just over three years.  The sample size was determined by a pre-specified adaptive statistical analysis that took into account the results of repeated interim analyses.  The study would complete for success, hazard or futility.  A total of 691 patients completed randomization and were included in the final analysis (with 102 exited or lost to follow up).  The study population was predominantly male with average age in 70s, and NYHA class II predominated.  LVEF was average 43% in the pacemaker group and 33% in the ICD group.

In the final analysis, biventricular pacing led to a 26% reduction in the combined endpoint of death, heart failure exacerbation or LV enlargement.  Excluding the echo endpoint, the clinical parameters remained favorable, with a 27% reduction in death or heart failure exacerbation.  The heart failure curves diverge early and remain parallel and the mortality curves diverge at about four years and continue to separate.

In last night’s investigator meeting, Dr. Anne Curtis, the study PI, called BLOCK HF a “game changer” that could lead to a new indication for biventricular pacing in patients with heart block and LV dysfunction.  She acknowledged the limitations of the trial including a high crossover rate (predominantly RV to BiV) and some missing echo data.  The very long follow up, however, could be interpreted as an advantage for the trial.

As an investigator in the trial, I was very eager to see this data and encouraged by the results.  The trial was slow to enroll with very long follow up and we were just happy to see it reach fruition.  Over the years, I’ve seen numerous patients develop heart failure after initiation of conventional pacing and it’s good to know that we may be able to prevent this if a new indication arises from the BLOCK HF data.

As in all trials, we will need to be cautious in the application of the data.  BLOCK HF should not spell the end for right ventricular pacing.  For those patients with normal LV function or those who get minimal ventricular pacing (such as sick sinus patients), conventional RV pacing is still appropriate and avoids the additional cost complexity and hazard of adding an LV lead.

Guest Post: An Electrophysiologist Looks At The New HRS/ACCF Pacemaker Guidelines Reply

Editor’s Note: The following guest post is published with the permission of its author,  Edward J. Schloss, MD, (Twitter ID @EJSMD) the medical director of cardiac electrophysiology at Christ Hospital in Cincinnati, OH.

Overview of the New HRS/ACCF Pacemaker Guidelines

by Edward J Schloss MD 

Since the development of the first dual chamber pacemakers in the 1980s, doctors have had the choice of using single or dual chamber devices in patients with traditional pacing indications. Although a number of pacemaker guideline consensus statements have been published over the years, none have provided specific guidance on specific device type or pacing mode selection.

This week the Heart Rhythm Society and American College of Cardiology Foundation published online the HRS/ACCF Expert Consensus Statement on Pacemaker Device and Mode Selection.  The authors intend this to be a supplement to the 2008 published pacemaker guidelines and classify indications in similar fashion, ranging from Class I (general agreement regarding benefit) to Class III (not useful, or harmful).  Biventricular pacing is not addressed in these documents, having been covered elsewhere .

The document is concise and clearly stated, and I would refer all those close to the field to the link above.  Below, I will add my own brief summary and comments.
Click to continue reading…