Effect of mitral isthmus block on development of atrial tachycardia following ablation for atrial fibrillation.

BACKGROUND: Successful mitral isthmus (MI) ablation may reduce recurrence of atrial fibrillation (AF) and macro-reentrant atrial tachycardia (AT) after pulmonary vein isolation (PVI) for AF. OBJECTIVE: To determine if achieving bidirectional MI conduction block (MIB) during circumferential pulmonary vein ablation (CPVA) plus left atrial linear ablation (LALA) affects development of AT. METHODS: Sixty consecutive patients with persistent (n = 25) or paroxysmal (n = 35) AF undergoing CPVA plus LALA at the MI and LA roof were evaluated in a prospective, nonrandomized study. RESULTS: PVI was achieved in all patients. Bidirectional MI block was achieved in 50 of 60 patients (83%). During 18 +/- 5 months follow-up, 12 patients (20%) developed recurrent AF and 15 (25%) developed AT. Patients in whom MIB was not achieved at initial ablation had four times higher risk of developing AT (P = 0.008, 95% confidence interval 1.43-11.48) versus patients with MIB. In 12 patients with AT undergoing repeat ablation, 22 ATs were identified, with reentry involving the MI in nine, the LA roof in six, and the ridge between the LA appendage and left PVs in seven. In patients with MIB at initial ablation, recovery of MI conduction was seen in eight of 13 undergoing repeat ablation. CONCLUSIONS: AT occurring after CPVA plus LALA is often due to incomplete MI ablation, but may also occur at the LA roof, and ridge between the LA appendage and left PVs. Failure to achieve MI block increases the risk of developing AT. Resumption of MI conduction may also be a mechanism for AT recurrence. (PACE 2010; 460-468).

Diagnosis and management of typical atrial flutter.

Typical atrial flutter (AFL) is a common atrial arrhythmia that may cause significant symptoms and serious adverse effects including embolic stroke, myocardial ischemia and infarction, and rarely a tachycardia-induced cardiomyopathy as a result of rapid atrioventricular conduction. As a result of the well-defined anatomic and electrophysiological substrate, and the relative pharmacologic resistance of typical AFL, radiofrequency catheter ablation has emerged in the past decade as a safe and effective first-line treatment. This article reviews the electrophysiology of typical AFL and the techniques currently used for its diagnosis and management.

Diagnosis and management of typical atrial flutter.

Can "past decade" be rephrased to refer to more specific years? Typical atrial flutter (AFL) is a common atrial arrhythmia that may cause significant symptoms and serious adverse effects, including embolic stroke, myocardial ischemia and infarction, and, rarely, a tachycardia-induced cardiomyopathy resulting from rapid atrioventricular conduction. As a result of the well-defined anatomic and electrophysiologic substrate and the relative pharmacologic resistance of typical AFL, radiofrequency catheter ablation has emerged since its first description in 1992 as a safe and effective first-line treatment. This article reviews the electrophysiology of typical AFL and techniques currently used for its diagnosis and management.

Prospective comparison of echocardiographic atrioventricular delay optimization methods for cardiac resynchronization therapy.

BACKGROUND: Atrioventricular (AV) delay optimization can be an important determinant of the response to cardiac resynchronization therapy (CRT) in patients with medically refractory heart failure and a ventricular conduction delay. OBJECTIVES: The purpose of this study was to compare two Doppler echocardiographic methods of AV delay optimization after CRT. METHODS: Forty consecutive patients (age 59 +/- 12 years) with severe heart failure, New York Heart Association class 3.1 +/- 0.4, QRS duration 177 +/- 23 ms, and left ventricular ejection fraction 26% +/- 6% referred for CRT were studied using two-dimensional Doppler echocardiography. In each patient, the acute improvement in stroke volume with CRT in response to two methods of AV delay optimization was compared. In the first method, the AV delay that produced the largest increase in the aortic velocity time integral (VTI) derived from continuous-wave Doppler (aortic VTI method) was measured. In the second method, the AV delay that optimized the timing of mitral valve closure to occur simultaneously with the onset of left ventricular systole was calculated from pulsed Doppler mitral waveforms at a short and long AV delay interval (mitral inflow method). RESULTS: The optimized AV delay determined by the aortic VTI method resulted in an increase in aortic VTI of 19% +/- 13% compared with an increase of 12% +/- 12% by the mitral inflow method (P <.001). The optimized AV delay by the aortic VTI method was significantly longer than the optimized AV delay calculated from the mitral inflow method (119 +/- 34 ms vs 95 +/- 24 ms, P <.001). There was no correlation in the AV delay determined by the two methods (r = 0.03). CONCLUSION: AV delay optimization by Doppler echocardiography for patients with severe heart failure treated with a CRT device yields a greater systolic improvement when guided by the aortic VTI method compared with the mitral inflow method.

Randomized prospective trial of atrioventricular delay programming for cardiac resynchronization therapy.

OBJECTIVES: The purpose of this study was to determine if AV delay optimization with continuous-wave Doppler aortic velocity-time integral (VTI) is clinically superior to an empiric program in patients treated with cardiac resynchronization therapy (CRT) for severe heart failure. BACKGROUND: The impact of AV delay programming on clinical outcomes associated with CRT is unknown. METHODS: A randomized, prospective, single-blind clinical trial was performed to compare two methods of AV delay programming in 40 patients with severe heart failure referred for CRT. Patients were randomized to either an optimized AV delay determined by Doppler echocardiography (group 1, n = 20) or an empiric AV delay of 120 ms (group 2, n = 20) with both groups programmed in the atriosynchronous biventricular pacing (VDD) mode. Optimal AV delay was defined as the AV delay that yielded the largest aortic VTI at one of eight tested AV intervals (between 60 and 200 ms). New York Heart Association (NYHA) functional classification and quality-of-life (QOL) score were compared 3 months after randomization. RESULTS: Immediately after CRT initiation with AV delay programming, VTI improved by 4.0 +/- 1.7 cm vs 1.8 +/- 3.6 cm (P < .02), and ejection fraction (EF) increased by 7.8 +/- 6.2% vs 3.4 +/- 4.4% (P < .02) in group 1 vs group 2, respectively. After 3 months, NYHA classification improved by 1.0 +/- 0.5 vs 0.4 +/- 0.6 class points (P < .01), and QOL score improved by 23 +/- 13 versus 13 +/- 11 points (P < .03) for group 1 vs group 2, respectively. CONCLUSIONS: Echocardiography-guided AV delay optimization using the aortic Doppler VTI improves clinical outcomes at 3 months compared to an empiric AV delay program of 120 ms.