Relief of drug refractory angina by biventricular pacing in heart failure

Cardiac Resynchronization Therapy Relieves Intractable Angina Due to Exercise-Induced Left Bundle Branch Block Without Left Ventricular Systolic Dysfunction: A Detailed Case Study

Exercise-induced left bundle branch block is rare and can be demonstrated with exercise testing. When the heart rate reaches a certain threshold, the QRS widens into left bundle branch block. This paper describes a patient with exercise-induced left bundle branch block related angina and dyspnea, who responded to cardiac resynchronization therapy. We documented the potential benefits of cardiac resynchronization therapy with a left ventricular rapid pacing study prior to its implantation. Although exercise-induced left bundle branch block is not a current indication for cardiac resynchronization therapy in patients such as ours, it could be considered when conventional drug therapy fails.

Pacing to reduce refractory angina in patients with severe coronary artery disease: a crossover pilot trial

Biventricular pacing (BiV) has been shown to reduce wall stress and workload in regions near the pacing sites. This trial investigated if BiV near the ischemic region would reduce chest pain in patients with refractory angina due to severe coronary artery disease (CAD). Eleven patients were implanted with BiV devices with leads positioned at or adjacent to their ischemic regions as detected by single-photon emission computed tomography (SPECT) and randomized to either pacing turned ON or OFF for 3 months, and then crossed over for 3 months. With pacing turned ON, a Dynamic atrioventricular (AV) delay was set for approximately 90% and 70% of the intrinsic AV delay at the resting heart rate and at the onset of symptoms, respectively. One patient was excluded from the analysis due to a large amount of RV pacing during the OFF periods (24-64%) and due to an inability to properly deliver therapy because of an excessive number of ventricular premature complexes. Overall, with the device ON vs. OFF, the number of angina episodes (0.8 ± 0.4 vs. 1.2 ± 0.7 per week, P = 0.03) and amount of nitroglycerin used (0.2 ± 0.1 vs. 1.0 ± 0.7 per week, P = 0.11) was lower with BiV pacing. Furthermore, the treadmill exercise time to symptoms trended higher (427 ± 65 vs. 408 ± 64 s, P = 0.19), and the sum of fluorodeoxyglucose-positron emission tomography (FDG-PET) scores trended lower (7.9 ± 3.5 vs. 12.0 ± 4.0, P = 0.11) with the device ON vs. OFF. Nevertheless, there were no significant differences in SPECT myocardial perfusion scores, left ventricle ejection fraction, wall motion score index, and quality of life scores with device programmed ON vs. OFF (all P > 0.05). In conclusion, this pilot study demonstrated that BiV-P at or near the ischemic region was feasible and associated with significant reductions in angina in patients with severe CAD. Adequately powered prospective studies are needed to confirm these findings.

Pharmacotherapy changes following pacemaker implantation in patients with bradycardia-tachycardia syndrome

The management of bradycardia-tachycardia syndrome (BTS) includes bradycardia and tachyarrhythmia therapy. At present, the treatment for symptomatic bradycardia in BTS patients is permanent cardiac pacing. The pharmacological treatment of atrial tachyarrhythmias comprises of rhythm and rate control, and prevention of thromboembolism. Patients with BTS often require both pacemaker and drug therapy. This article reviews the interactions of pacing and drug therapies in BTS. Drugs that alter cardiac electrophysiological properties may influence pacemaker indications, pacing mode selection, efficacy of pacing algorithms and pacing performance. Pacing by preventing drug-induced bradycardia increases the safety of pharmacotherapy and, thus, allows the intensification of those treatments. Pacing therapy and antiarrhythmic drugs used together as a hybrid therapy have a synergistic effect in the prevention of atrial tachyarrhythmias. Atrial-based pacing may reduce atrial tachyarrhythmia burden, allowing reduction of rhythm and rate control. Contemporary pacemakers' memory functions may help guide rhythm and rate control, as well as anticoagulation pharmacotherapy.

Echocardiographic Assessment of Ventricular Asynchrony in Dilated Cardiomyopathy and Congenital Heart Disease: Tools and Hopes

Ventricular dyssynchrony is a relatively common problem in patients with heart failure, in particular those with wide QRS complex, and appears to have a deleterious effect on the natural history of heart failure, as it has been associated with increased mortality. Mechanistic studies, observational evaluations, and randomized trials have consistently demonstrated the beneficial effects of cardiac resynchronization therapy (CRT) in patients with moderate-to-severe chronic systolic heart failure and ventricular dyssynchrony who have failed optimal medical treatment. However, despite the promising results, it is estimated that in approximately 30% of patients undergoing CRT, the symptoms of heart failure do not improve or become even worse. One of the most important reasons for this failure is probably the lack of distinct mechanical dyssynchrony before implantation. A number of echocardiographic tools have been developed during the past 3 years for quantitative measurement of the severity of dyssynchrony before and after CRT. This review discusses the actual and potential role of different echocardiographic techniques in selection of patients and optimization of CRT and the value of some new clinical applications such as in congenital heart disease.

Long-term follow-up of patients with refractory heart failure and myocardial ischemia treated with cardiac resynchronization therapy

Studies in patients without coronary artery disease have shown the restoration of glucose metabolism by cardiac resynchronization therapy (CRT) without changes in myocardial perfusion. We report on the long-term outcome of CRT in 24 patients with severe heart failure (HF) and advanced coronary artery disease not amenable for revascularization. All patients had documented myocardial ischemia on stress (99)Tc-sestamibi single-photon emission computed tomography, and all underwent successful implantations of CRT systems. The mean left ventricular ejection fraction was 21%+/- 4%, 19 patients (79%) had anginal complaints and 20 (83%) had diffuse three-vessel disease. During a follow-up of 13 +/- 0.7 months, two patients died suddenly and one died of progressive HF. Among survivors, functional capacity decreased from New York Heart Association class 3.2 +/- 1.4 to 2.1 +/- 1.0 (P < 0.01), and the Minnesota questionnaire quality-of-life scores decreased from 43 +/- 15 to 28 +/- 13 (P < 0.01). Despite an increase from 264 +/- 104 to 385 +/- 121 m in distance walked in 6 minutes (P < 0.01), the number of anginal attacks/week remained unchanged (4.7 +/- 0.7 to 4.5 +/- 0.6). Patients with advanced HF, stable angina, and documented myocardial ischemia may undergo safe and successful implantations of CRT systems.

Established and evolving indications for cardiac resynchronisation

Randomised trials involving large number of patients have demonstrated the benefits of cardiac resynchronisation therapy (CRT) in patients with heart failure who have failed optimal medical treatment. Echocardiography plays an important role in defining dyssynchrony which is key to optimal patient selection. The electrocardiographic criteria for patient selection is supplemented by the finding of dyssynchrony on Doppler myocardial imaging, and echocardiography with Doppler myocardial imaging may eventually replace the electrocardiographic criteria for selection of patients who derive benefit from CRT.