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ACC 2005 ANNUAL SESSION HIGHLIGHT

Cardiac Arrhythmias

Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida

^_* Reprint requests and correspondence: Dr. Jamie B. Conti, University of Florida, Division of Cardiovascular Medicine, Box 100277, Gainesville, Florida 32610-0277. (Email: contijb{at}medicine.ufl.edu).

	The Optimal Pharmacological Therapy in Implantable Defibrillator Patients (OPTIC) trial, presented by Stuart J. Connolly for the OPTIC Investigators

Top The Optimal Pharmacological... The Prospective, Randomized, and... The Cardiac Resynchronization... The Chronicle Offers Management... References

 
The purpose of the OPTIC trial (1) was to determine whether antiarrhythmic therapy would reduce shocks (appropriate or not) compared to beta-blocker therapy alone. Patients were considered eligible if they had either spontaneous ventricular tachycardia (VT) or left ventricular ejection fraction (EF) 40%, spontaneous ventricular fibrillation (VF), or inducible VT or VF. A total of 412 patients were randomized to three groups: beta-blockers, amiodarone plus beta-blockers, or sotalol. The investigators found that antiarrhythmic therapy was more effective than beta-blockade alone (p = 0.00006) and concluded that after implantable cardioverter-defibrillator (ICD) implantation for spontaneous or inducible VT or VF, the annual rate of shock is 30% even with beta-blockers and optimal dual-chamber ICD programming, and that amiodarone reduces shocks by 74%. "This study shows shocks are very common in these patients, and that amiodarone is really effective in reducing their number," said Dr. Connolly. "The results represent a huge reduction in shocks and a big improvement in quality of life."

	The Prospective, Randomized, and Controlled Study on Effect of Catheter Ablation for the Cure of Atrial Fibrillation (CACAF) study, presented by Emmanuele Bertaglia for the CACAF Investigators

Top The Optimal Pharmacological... The Prospective, Randomized, and... The Cardiac Resynchronization... The Chronicle Offers Management... References

 
The CACAF study (2) assessed the impact of antiarrhythmic therapy (ADT) alone, or therapy combined with both right and left atrial ablation, in preventing atrial fibrillation (AF) recurrence in patients with paroxysmal or persistent AF who have already failed ADT. A total of 137 patients were randomized to either ablation and ADT or ADT alone (controls). Follow-up was for 12 months. Of the control group patients, 94% versus 40.6% of the ablation group had at least one AF recurrence (p < 0.001). The investigators concluded that ablation therapy, combined with ADT, was superior to ADT alone in preventing atrial arrhythmia recurrences. "All the patients in our study had a very long history of atrial fibrillation," said Dr. Bertaglia, Civic Hospital of Mirano, and Dr. Guiseppe Stabile, Casa di Cura S. Michele, Maddaloni, Italy. "They had already failed at least two or three antiarrhythmic drugs. They are the most difficult patients we encounter in clinical practice. Yet they responded after the execution of just one ablation procedure," Drs. Bertaglia and Stabile agreed.

	The Cardiac Resynchronization-Heart Failure (CARE-HF) study, presented by John G. F. Cleland for the CARE-HF Investigators

Top The Optimal Pharmacological... The Prospective, Randomized, and... The Cardiac Resynchronization... The Chronicle Offers Management... References

 
The CARE-HF study (3) was an international, randomized, unblinded parallel group trial that evaluated the effect of cardiac resynchronization therapy (CRT) on morbidity and mortality. Included were 813 patients followed for a mean of 29.4 months. Patients with New York Heart Association (NYHA) functional class III and IV heart failure owing to left ventricular systolic dysfunction and cardiac dyssynchrony were randomized to receive either medical treatment alone or medical treatment with CRT. The primary end point was the time to death from any cause or any unplanned hospitalization for a major cardiovascular event.

There were 82 deaths in the CRT group compared to 120 in the medical therapy group (p < 0.002). The primary end point was reached by 159 patients in the cardiac resynchronization group, as compared with 224 patients in the medical therapy group (39% vs. 55%; p < 0.001). The investigators concluded that in patients with heart failure and cardiac dyssynchrony, CRT reduces the risk of death. This benefit was seen as additive to standard pharmacologic therapy. "We now have overwhelming evidence that cardiac resynchronization therapy saves lives, slows the progression of heart failure, and improves symptoms and morbidity in many heart failure patients; these results add to previous study results demonstrating improvement in heart failure symptoms and quality of life with CRT," said Professor John G. F. Cleland, Chairman of the CARE-HF Steering Committee and head of the Department of Cardiology, Castle Hill Hospital, Kingston-upon-Hull, United Kingdom.

	The Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) study, presented by Robert Bourge for the COMPASS Investigators

Top The Optimal Pharmacological... The Prospective, Randomized, and... The Cardiac Resynchronization... The Chronicle Offers Management... References

 
The COMPASS-HF study (4) was a randomized, single-blind (patient), controlled trial of specialized heart failure (HF) care alone in a blocked clinician access group (BCA) versus specialized HF care and clinical care guidelines using an implantable hemodynamic monitor system (IHM, Chronicle, Medtronic Inc., Minneapolis, Minnesota) in a total clinical access group (TCA). Patients enrolled had either NYHA functional class III or IV HF. Both systolic and diastolic HF patients were included.

Two hundred and seventy-four patients were randomized either to BCA (n = 140) or TCA (n = 134), and blinded to that randomization for six months. Physicians were not blinded. All patients transmitted this IHM data weekly, and standard scripts were used during patient contact to maintain the blindness.

The primary safety end points of freedom from system-related complications and sensor lead failure were exceeded, with 0 lead sensor failures and <10% overall system complication rate. Overall, 25% fewer patients in the TCA group had an event when compared to the BCA group (74 vs. 102 patients; p = 0.27). Of note, the overall event rate was significantly less than the hypothesized event rate (0.70 and 0.89 in the TCA vs. BCA group, respectively, compared to the 1.2 hypothesized), possibly explaining the lack of statistical significance. Most of the events (84%) were HF hospitalization. The TCA group had a 21% risk reduction for this end point (p = 0.029). Improvement was also seen in the clinical composite score.

Interestingly, the effect of Chronicle-guided care was seen equally in patients with systolic and diastolic HF regarding cumulative events. Another subgroup of note was NYHA class III patients. The TCA patients had a 41% reduction (p = 0.03) in cumulative events when compared to those randomized to BCA.

The COMPASS-HF study demonstrates that the system is safe and reliable, with benefit in those patients with both systolic and diastolic dysfunction. Dr. Bourge concluded that "A heart failure management strategy based on continuously monitored intra-cardiac pressures in patients already on the best available therapy and heart failure care directed by expert heart failure clinicians significantly improved patient morbidity."

Many noteworthy abstracts were also presented in the oral sessions. Of particular importance were several abstracts featured in a session entitled "Mapping and Ablation of Ventricular Tachycardia." Yarlagadda et al. (5) studied 29 patients referred for catheter ablation of repetitive monomorphic ventricular ectopy (RMVE) to determine the incidence of tachycardia-induced cardiomyopathy and to assess the impact of ablation on left ventricular (LV) function. Patients with normal and impaired (n = 10) LV function were included. Ectopy was successfully ablated from within the right ventricular outflow tract (RVOT) in 25 (86%) patients, including 9 (90%) patients with impaired LV function. In the patients with impaired LV function, seven had follow-up assessment of LV function, with demonstrated improvement. The investigators concluded that one-third of these patients had tachycardia-induced cardiomyopathy, and that ablation may normalize EF.

Next, Gonzalez et al. (6) studied 12 patients with frequent ICD shocks who underwent ablation of hemodynamically unstable VT. They hypothesized that identification of regions of slow conduction during sinus rhythm might facilitate catheter ablation of hemodynamically unstable VT, and that these regions would show late potentials (LP) with activation times independent of the direction of activation. The researchers concluded that the response to different directions of activation allowed identification of LP that might participate in re-entrant VT and that ablation of these potentials can eliminate unmappable VT.

Miljoen et al. (7) presented work describing three-dimensional (3D) electroanatomical mapping in 11 patients with arrhythmogenic right ventricular (RV) cardiomyopathy/dysplasia and found that detailed 3D electroanatomical mapping was helpful in defining the VT mechanism and in reconstructing their circuits in patients with arrhythmogenic RV dysplasia.

Finally Jacobson et al. (8) investigated whether non-contact unipolar mapping can define arrhythmogenic substrate and VT circuits. Using a pig model, myocardial infarction (MI) was induced in the left anterior descending distribution. Dynamic substrate mapping was performed and found to be a reliable method to localize arrhythmogenic substrate in this model. Investigators suggested that this technique might be useful for ablation of unmappable VT post-MI.

In a separately featured oral session, five abstracts were presented addressing ablation of AF and modalities to aid in avoiding esophageal injury.

Cummings et al. (9) evaluated and compared different modalities for determining anatomical variation and proximity of the esophagus to the posterior wall of the left atrium. Fifty patients were imaged prior to pulmonary vein antrum isolation, and the closest distance between the left atrial (LA) endocardial surface and the esophageal lumen was measured. They found significant variability in the location of closest contact, with some close to the pulmonary vein antral regions and <3 mm in distance. They concluded that integrating 3D-computed tomography scans into mapping systems might be a reliable tool in identifying areas of increased risk for LA esophageal perforation.

Ren et al. (10) evaluated lesion morphologic and wall thickness changes with radiofrequency (RF) delivered at the LA posterior wall-esophageal wall (LAPW-eso) using intracardiac echocardiography (ICE). A total of 42 patients undergoing LA pulmonary vein isolation were included. The LAPW-eso wall thickness and changes in echogenic lesion thickness were measured under routine circumstances and during RF power titration using ICE monitoring. These investigators found that lesion changes may be controlled and limited with power titration under ICE lesion monitoring. In a related abstract (11) the investigators demonstrated that the real-time ICE imaging of the LAPW-eso region might provide an important tool to monitor so as to avoid inadvertent esophageal injury during LA ablation.

Lemola et al. (12) described the topographical anatomy of the esophagus and the posterior LA using computed tomography (CT). Fifty patients underwent a spiral CT with 3D reconstruction of the chest prior to an AF ablation procedure. The mean length and width dimensions of the esophagus in contact with the posterior LA were 58 ± 14 mm and 13 ± 6 mm, respectively. In 98% of patients, there was a fat layer between the esophagus and the posterior LA. The researchers found the esophagus had a variable course but was in close contact with the LA over a large area, often lying within the ablation zone. They suggested that the layer of adipose tissue may serve to insulate the esophagus from thermal injury.

Finally, Cesario et al. (13) (presented by Charles Swerdlow) hypothesized that monitoring of esophageal temperature may detect early temperature rises to prevent esophageal injury. They studied 12 patients using an esophageal temperature probe positioned at the level of the 8-mm ablation tip. Maximum power and temperature were 40 to 50 W/50° to 55°. Ablation was terminated when there was an abrupt rise in esophageal temperature (<0.5°). Esophageal temperature rose in 11 patients (92%), although they had no acute or chronic complications. The researchers concluded that esophageal temperature rises abruptly during LA catheter ablation at sites adjacent to the esophagus and that monitoring the esophageal temperature may reduce the risk of LA-esophageal fistula.

An enormous amount of scientific information was presented at this year’s Scientific Sessions, making it impossible to recognize the efforts of each investigator and the contributions each one made to the success of the Clinical Cardiac Electrophysiology Section. The aforementioned presentations were also formally offered at the "Highlights" sessions on Wednesday, March 9, 2005.

	References

Top The Optimal Pharmacological... The Prospective, Randomized, and... The Cardiac Resynchronization... The Chronicle Offers Management... References

 

1. Connolly SJ, OPTIC Investigators Optimal Pharmacological Therapy in Implantable Defibrillator Patients (OPTIC) trial. 2005Presented at: ACC 54th Annual Meeting; March 6–9; Orlando, FL.
2. Bertaglia E, CACAF Investigators Catheter Ablation for the Cure of Atrial Fibrillation (CACAF) study. 2005Presented at: ACC 54th Annual Meeting; March 6–9; Orlando, FL.
3. Cleland JGF, Daubert J-C, Erdman E, et al. Cardiac Resynchronization-Heart Failure (CARE-HF) Study Investigators The effect of cardiac resynchronization on morbidity and mortality in heart failure N Engl J Med 2005;352:1539-1549.[Abstract/Free Full Text]
4. Bourge R, COMPASS Investigators The Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) study. 2005Presented at: ACC 54th Annual Meeting; March 6–9; Orlando, FL.
5. Yarlagadda RK, Iwai S, Stein KM, et al. Tachycardia-induced cardiomyopathy in patients with repetitive monomorphic ventricular ectopy originating from the right ventricular outflow tract(abstr) J Am Coll Cardiol 2005;45(Suppl A):105A.
6. Gonzalez MD, Rivera J, Velasco DN, et al. Catheter ablation of unstable ventricular tachycardia guided by late potentials(abstr) J Am Coll Cardiol 2005;45(Suppl A):105A.
7. Miljoen H, State S, De Chillou C, et al. Electroanatomic mapping characteristics of ventricular tachycardia in patients with arrhythmogenic right ventricular dysplasia(abstr) J Am Coll Cardiol 2005;45(Suppl A):106A.
8. Jacobson JT, Afonso VX, Eisenman G, et al. Characterization of arrhythmogenic substrate and ventricular tachycardia circuits with non-contact unipolar mapping in a porcine model of myocardial infarction(abstr) J Am Coll Cardiol 2005;45(Suppl A):106A.
9. Cummings JE, Marrouche NF, Schweikert R, et al. Assessment of the highly variable course of the esophagus and its proximity to the left atrial endocardium by 3D CT scan(abstr) J Am Coll Cardiol 2005;45(Suppl A):114A.
10. Ren J-F, Callans DJ, Marchlinski FE, et al. Avoiding esophageal injury with power titrating during left atrial ablation for atrial fibrillationan intracardiac echocardiographic imaging study. (abstr) J Am Coll Cardiol 2005;45(Suppl A):114A.
11. Ren J-F, Marchlinski FE, Callans DJ. Esophageal imaging characteristics and structural measurement during left atrial ablation for atrial fibrillationan intracardiac echocardiographic study. (abstr) J Am Coll Cardiol 2005;45(Suppl A):114A.
12. Lemola K, Schneider M, Desjardins B, et al. Computerized tomographic analysis of the anatomy of the left atrium and the esophagusimplications for left atrial catheter ablation. (abstr) J Am Coll Cardiol 2005;45(Suppl A):114A.
13. Cesario D, Shivkumar K, Valderrabano M, et al. Esophageal temperature monitoring during left atrial catheter ablation for atrial fibrillation(abstr) J Am Coll Cardiol 2005;45(Suppl A):114A.

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