Background Previous studies have suggested that cardiac resynchronization achieved through atrial-synchronized biventricular pacing produces clinical benefits in patients with heart failure who have an intraventricular conduction delay. We conducted a double-blind trial to evaluate this therapeutic approach. Methods Four hundred fifty-three patients with moderate-to-severe symptoms of heart failure associated with an ejection fraction of 35 percent or less and a QRS interval of 130 msec or more were randomly assigned to a cardiac-resynchronization group (228 patients) or to a control group (225 patients) for six months, while conventional therapy for heart failure was maintained. The primary end points were the New York Heart Association functional class, quality of life, and the distance walked in six minutes. Results As compared with the control group, patients assigned to cardiac resynchronization experienced an improvement in the distance walked in six minutes (+39 vs. +10 m, P=0.005), functional clas...

Cardiac Resynchronization in Chronic Heart Failure

ContextCardiac resynchronization therapy (CRT) through biventricular pacing
is an effective treatment for heart failure (HF) with a wide QRS; however,
the outcomes of patients requiring CRT and implantable cardioverter defibrillator
(ICD) therapy are unknown.ObjectiveTo examine the efficacy and safety of combined CRT and ICD therapy in
patients with New York Heart Association (NYHA) class III or IV congestive
HF despite appropriate medical management.Design, Setting, and ParticipantsRandomized, double-blind, parallel-controlled trial conducted from October
1, 1999, to August 31, 2001, of 369 patients with left ventricular ejection
fraction of 35% or less, QRS duration of 130 ms, at high risk of life-threatening
ventricular arrhythmias, and in NYHA class III (n = 328) or IV (n = 41) despite
optimized medical treatment.InterventionsOf 369 randomized patients who received devices with combined CRT and
ICD capabilities, 182 were controls (ICD activated, CRT off) and 187 were
in the CRT group (ICD activated, CRT on).Main Outcome MeasuresThe primary double-blind study end points were changes between baseline
and 6 months in quality of life, functional class, and distance covered during
a 6-minute walk. Additional outcome measures included changes in exercise
capacity, plasma neurohormones, left ventricular function, and overall HF
status. Survival, incidence of ventricular arrhythmias, and rates of hospitalization
were also compared.ResultsAt 6 months, patients assigned to CRT had a greater improvement in median
(95% confidence interval) quality of life score (–17.5 [–21 to
–14] vs –11.0 [–16 to –7], P =
.02) and functional class (–1 [–1 to –1] vs 0 [–1
to 0], P = .007) than controls but were no different
in the change in distance walked in 6 minutes (55 m [44-79] vs 53 m [43-75], P = .36). Peak oxygen consumption increased by 1.1 mL/kg
per minute (0.7-1.6) in the CRT group vs 0.1 mL/kg per minute (–0.1
to 0.8) in controls (P = .04), although treadmill
exercise duration increased by 56 seconds (30-79) in the CRT group and decreased
by 11 seconds (–55 to 12) in controls (P<.001).
No significant differences were observed in changes in left ventricular size
or function, overall HF status, survival, and rates of hospitalization. No
proarrhythmia was observed and arrhythmia termination capabilities were not
impaired.ConclusionsCardiac resynchronization improved quality of life, functional status,
and exercise capacity in patients with moderate to severe HF, a wide QRS interval,
and life-threatening arrhythmias. These improvements occurred in the context
of underlying appropriate medical management without proarrhythmia or compromised
ICD function.

https://jamanetwork.com/journals/jama/articlepdf/1108361/JOC30332.pdf

Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial.

Background—Previous studies of pacing therapy for dilated congestive heart failure (CHF) have not established the relative importance of pacing site, AV delay, and patient heterogeneity on outcome. These variables were compared by a novel technique that evaluated immediate changes in hemodynamic function during brief periods of atrial-synchronous ventricular pacing. Methods and Results—Twenty-seven CHF patients with severe left ventricular (LV) systolic dysfunction and LV conduction disorder were implanted with endocardial pacing leads in the right atrium and right ventricle (RV) and an epicardial lead on the LV and instrumented with micromanometer catheters in the LV, aorta, and RV. Patients in normal sinus rhythm were stimulated in the RV, LV, or both ventricles simultaneously (BV) at preselected AV delays in a repeating 5-paced/15-nonpaced beat sequence. Maximum LV pressure derivative (LV+dP/dt) and aortic pulse pressure (PP) changed immediately at pacing onset, increasing at a patient-specific optimal...

Effect of Pacing Chamber and Atrioventricular Delay on Acute Systolic Function of Paced Patients With Congestive Heart Failure

Long-term clinical effect of hemodynamically optimized cardiac resynchronization therapy in patients with heart failure and ventricular conduction delay.

Rhythmic and effective cardiac contraction depends on appropriately timed generation and spread of cardiac electrical activity. The basic cellular unit of such activity is the action potential, whi...

Arrhythmogenic Ion-Channel Remodeling in the Heart: Heart Failure, Myocardial Infarction, and Atrial Fibrillation

Ventricular contraction abnormalities in dilated cardiomyopathy: effect of biventricular pacing to correct interventricular dyssynchrony.

Multisite Pacing Effect on LV Function Introduction: We hypothesized that simultaneous right and left ventricular apical pacing would result in improvement in left ventricular function due to improved coordination of segmental ventricular contraction Structural changes in ventricular muscle present in dilated cardiomyopathy compromise ventricular excitation and mechanical contraction



Methods and Results: Eleven patients with depressed left ventricular function having cardiac surgery underwent epicardial multisite pacing with continuous transesophageal echocardiographic imaging Quantitative measurement of percent fractional area change was performed, and segmental changes in contraction sequence resulting from simultaneous right and left ventricular pacing were assessed by application of phase analysis to recorded transesophageal images There was no statistically significant difference between the paced QRS duration achieved with simultaneous right and left ventricular apical pacing and the native QRS duration (139 ± 39 msec vs 106 ± 18 msec, P = NS), but all other paced modes resulted in longer QRS durations Percent fractional area change improved with simultaneous right and left ventricular apical pacing hut not with other paced modes (415 ± 119 vs 343 ± 97, P < 001) Phase analysis demonstrated a resequencing of segmental left ventricular activation/contraction when compared to baseline ventricular activation



Conclusion: Simultaneous right and left ventricular apical pacing results in acute improvements in global ventricular performance in patients with depressed ventricular function Improvements may result from pacing-induced global coordination through recruitment of left and right ventricular apical and septal segments critical to effective ventricular contraction

Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function.

Walter F. Kerwin

Papers

Ventricular contraction abnormalities in dilated cardiomyopathy: effect of biventricular pacing to correct interventricular dyssynchrony.

Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function.