Left Ventricular Endocardial Pacing
Pierre Bordachar, Nicolas Derval, Sylvain Ploux, Stephane Garrigue, Philippe Ritter, Michel Haissaguerre, Pierre Jais
Bordachar and colleagues review the risks and challenges associated with endocardially placing a left ventricular lead in patients who cannot have a lead placed into an appropriate coronary vein. Theoretically, endocardial placement has several advantages, including the ability to place the lead at the site with the most favorable hemodynamic benefit regardless of the anatomy of the coronary venous system and more physiologic endocardial-to-epicardial depolarization. The risks include thromboembolic complications and damage to the mitral valve for leads placed transseptally. The adoption of endocardial stimulation will require developing safe and durable instrumentation and intraprocedural methods to identify the optimal site of stimulation.
Expanding the Indications for CRT
Rutger J. Van Bommel, Victoria Delgado, Martin J. Schalij, Jeroen J. Bax
Cardiac resynchronization therapy (CRT) is an effective treatment for patients with drug-refractory, chronic heart failure. Based on the results of clinical trials, current guidelines consider CRT a Class I indication for heart failure patients in New York Heart Association (NYHA) functional class III to IV, with depressed left ventricular ejection fraction ≤35%, and with a QRS complex ≥120 ms. Recent trials have suggested that some patients who do not fulfill these criteria may also benefit from CRT. Van Bommel and colleagues review these trials and discuss the role of CRT in patients in NYHA functional class I to II or with a normal QRS complex.
CRT Use Should Be Restricted to the Current Guidelines
Thomas H. Marwick, Richard A. Grimm
In a commentary responding to the viewpoint paper by Van Bommel and colleagues, Marwick and Grimm argue that the current guidelines restricting the use of cardiac resynchronization therapy (CRT) implantation should not be expanded. They note that clinical practice has drifted away from the evidence base from clinical trials, involving patients who are older and with more comorbidities, with 10% having ejection fraction >35% and 6% having an ejection fraction >40%. They are also more skeptical of clinical trials advocating the expansion of CRT.
One-Quarter of CRT Device Implants Do Not Meet Established Criteria
Adam S. Fein, Yongfei Wang, Jeptha P. Curtis, Frederick A. Masoudi, Paul D. Varosy, Matthew R. Reynolds, on behalf of the National Cardiovascular Data Registry
Fein and colleagues used data from the National Cardiovascular Data Registry's Implantable Cardiac-Defibrillator Registry to determine what percentage of patients undergoing cardiac resynchronization therapy (CRT) device implantation do not meet consensus guidelines. “Off-label” implants were defined as those for patients in whom the ejection fraction was >35%, the New York Heart Association (NYHA) functional class was below III, or the QRS duration was <120 ms in the absence of a documented need for ventricular pacing. In over 45,000 implants, 24% of devices were placed without meeting all 3 implant criteria, most often due to NYHA functional class below III (13.1% of implants) or QRS duration <120 ms (12.0%). These data indicate that nearly 1 in 4 patients receiving CRT devices do not meet guideline-based indications.
Endocardial Mapping Can Identify Optimal Location for LV Pacing
David D. Spragg, Jun Dong, Barry J. Fetics, Robert Helm, Joseph E. Marine, Alan Cheng, Charles A. Henrikson, David A. Kass, Ronald D. Berger
Spragg and colleagues postulated that endocardial biventricular (BiV) stimulation would provide more flexibility in left ventricular (LV) site selection and yield more natural transmural activation patterns. The peak rate of left ventricular pressure rise (dP/dtmax) was measured during BiV pacing at the right ventricular apex (RVA) and various LV endocardial sites. Endocardial BiV improved dP/dtmax over RVA pacing in all patients. In patients with pre-existing cardiac resynchronization therapy (CRT) leads, LV endocardial and epicardial pacing at the same site yielded equivalent dP/dtmax values, but other sites in the LV often produced higher dP/dtmax values. CRT delivered at the best LV endocardial sites is more effective than via the typical location in the mid-LV free wall.
Editorial Comment: Nicolas Derval, Pierre Jaïs, p.782
Pericardial Fat May Predispose to AF
M. Obadah Al Chekakie, Christine C. Welles, Raymond Metoyer, Ahmed Ibrahim, Adam R. Shapira, Joseph Cytron, Peter Santucci, David J. Wilber, Joseph G. Akar
Pericardial fat is a visceral adipose depot that possesses significant inflammatory properties. Atrial fibrillation (AF) is associated with inflammation and obesity. Al Chekakie and colleagues investigated the relationship between AF and pericardial fat using computed tomography scans to quantify the pericardial fat volume. Patients with AF had significantly more pericardial fat compared with patients in sinus rhythm. This association was independent of age, hypertension, sex, left atrial enlargement, valvular heart disease, left ventricular ejection fraction, diabetes, and body mass index. Pericardial fat may predispose to AF independent of traditional risk factors.
Elevated CRP Is Associated With Increased Risk of AF, But Probably Not Causative
Sarah C. W. Marott, Børge G. Nordestgaard, Jeppe Zacho, Jens Friberg, Gorm B. Jensen, Anne Tybjærg-Hansen, Marianne Benn
Marott and colleagues investigated the relationship between atrial fibrillation (AF) and C-reactive protein (CRP) in over 46,000 subjects with over 2,000 cases of AF. Individuals were genotyped for 4 CRP gene polymorphisms, and their high-sensitivity CRP levels were measured. A CRP level in the upper versus lower quintile was associated with a 2.2-fold increased risk of AF, which attenuated slightly after multifactorial adjustment. Genotype combinations of the 4 CRP polymorphisms were associated with up to a 63% increase in plasma CRP levels, but not with increased risk of AF. These findings suggest that elevated plasma CRP does not directly increase the risk of AF but is rather a biomarker of the risk.
Characterization of AT Arising From the Noncoronary Aortic Sinus
Xingpeng Liu, Jianzeng Dong, Siew Yen Ho, Ashok Shah, Deyong Long, Ronghui Yu, Ribo Tang, Meleze Hocini, Michel Haissaguerre, Changsheng Ma
Liu and colleagues used 3-dimensional electroanatomical mapping, computed tomography imaging, and excised hearts to characterize atrial tachycardia (AT) arising adjacent to the noncoronary aortic sinus (NCAS-AT). During NCAS-AT, the para-Hisian area of the right atrium and the anteroseptal region of the left atrium (LA) were activated almost simultaneously. In reference patients, NCAS pacing reproduced the bi-atrial activation pattern of NCAS-AT. Anatomically, the wall of the NCAS did not contain myocardial tissue but was intimately related to the paraseptal regions of the atria. NCAS-AT has distinct atrial activation patterns, which can be partly explained by its anatomical relationship with the atria.
Calcium Clock Underlies AVJ Rate Acceleration During Sympathetic Stimulation
Daehyeok Kim, Tetsuji Shinohara, Boyoung Joung, Mitsunori Maruyama, Eue-Keun Choi, Young Keun On, Seongwook Han, Michael C. Fishbein, Shien-Fong Lin, Peng-Sheng Chen
Kim and colleagues studied the importance of rhythmic spontaneous sarcoplasmic reticulum calcium (Ca) release (the “Ca clock”) in atrioventricular junction (AVJ) automaticity. The transmembrane potential and intracellular Ca were measured in Langendorff-perfused canine AVJ preparations. The wavefront from the leading pacemaker site propagated first through the slow pathway, then the fast pathway, and then the atria. There was no late diastolic Ca elevation at baseline, but it developed with isoproterenol infusion. Ryanodine markedly slowed the rate of spontaneous AVJ rhythm and prevented the acceleration with isoproterenol. These results confirm that the Ca clock mediates AVJ rate acceleration during sympathetic stimulation.
Catheter Aortic Valve Implantation
Case Series: Transapical Aortic Valve Implantation in 175 Patients
Miralem Pasic, Axel Unbehaun, Stephan Dreysse, Thorsten Drews, Semih Buz, Marian Kukucka, Alexander Mladenow, Tom Gromann, Roland Hetzer
Pasic and colleagues developed a transapical aortic valve implantation (TAVI) program in 2008 and herein describe their outcomes in the first 175 patients. The patients' mean age was 80 years, with a mean Society of Thoracic Surgeons score of 23%, including 10 patients in cardiogenic shock. Technical success of the procedure was 100%, and there was no conversion to conventional surgery. The 30-day mortality was 3.6% for all patients without cardiogenic shock and 30% for the patients with cardiogenic shock. Survival at 1, 6, and 12 months was 95%, 86%, and 83%, respectively. TAVI has become the primary choice of treatment for high-risk patients with severe aortic valve stenosis at this institution.