Myocardial Fibrosis Predicts Ventricular Arrhythmias and Sudden Death After Cardiac Electronic Device Implantation

BACKGROUND

Increasing evidence supports a link between myocardial fibrosis (MF) and ventricular arrhythmias.

OBJECTIVES

The purpose of this study was to determine whether presence of myocardial fibrosis on visual assessment (MFVA) and gray zone fibrosis (GZF) mass predicts sudden cardiac death (SCD) and ventricular fibrillation/sustained ventricular tachycardia after cardiac implantable electronic device (CIED) implantation.

METHODS

In this prospective study, total fibrosis and GZF mass, quantified using cardiovascular magnetic resonance, was assessed in relation to the primary endpoint of SCD and the secondary, arrhythmic endpoint of SCD or ventricular arrhythmias after CIED implantation.

RESULTS

Among 700 patients (age 68.0 ± 12.0 years), 27 (3.85%) experienced a SCD and 121 (17.3%) met the arrhythmic endpoint over median 6.93 years (IQR: 5.82-9.32 years). MFVA predicted SCD (HR: 26.3; 95% CI: 3.7-3,337; negative predictive value: 100%). In competing risk analyses, MFVA also predicted the arrhythmic endpoint (subdistribution HR: 19.9; 95% CI: 6.4-61.9; negative predictive value: 98.6%). Compared with no MFVA, a GZF mass measured with the 5SD method (GZF5SD) >17 g was associated with highest risk of SCD (HR: 44.6; 95% CI: 6.12-5,685) and the arrhythmic endpoint (subdistribution HR: 30.3; 95% CI: 9.6-95.8). Adding GZF5SD mass to MFVA led to reclassification of 39% for SCD and 50.2% for the arrhythmic endpoint. In contrast, LVEF did not predict either endpoint.

CONCLUSIONS

In CIED recipients, MFVA excluded patients at risk of SCD and virtually excluded ventricular arrhythmias. Quantified GZF5SD mass added predictive value in relation to SCD and the arrhythmic endpoint.

Second European Society of Cardiology Cardiac Resynchronization Therapy Survey: the Italian cohort

AIM

Adherence to guidelines was not homogeneous in Europe, according to the survey on cardiac resynchronization therapy conducted in 2008-2009. The aim of our study was to compare the results in the Italian and European cohorts of the Second European Cardiac Resynchronization Therapy Survey.

METHODS

Patients' characteristics, procedural data and follow-up were collected. Italian records were compared with European countries.

RESULTS

Italian hospitals enrolled 526 patients. The italian cohort was older (71.6 ± 9.5 vs. 68.4 ± 10.8; P < 0.00001), had less severe NYHA class (>II 47.2 vs. 59.6%; P < 0.00001), higher ejection fraction (30.3 ± 7.4 vs. 28.4 ± 8.2%; P < 0.00001), and less atrial fibrillation prevalence (34.4 vs. 41.2%; P = 0.00197) than the European cohort. Italian patients were more frequently hospitalized for heart failure in the previous year (51.9 vs. 46.2%; P = 0.01118) and had lower mean QRS duration (151 ± 26 vs. 157 ± 27 ms; P < 0.0001). CRT-D were more often implanted in Italian patients (79.3 vs. 69.3%; P < 0.00001). The complication rate was similar (4.6% vs. 5.6%; ns). The rate of use of ACEi/ARBs in Italy was lower than in Europe (77.2 vs. 86.9%; P < 0.00001). Patients were followed up in the implantation centre (92.1 vs. 86%; P = 0.00014), but rarely with remote monitoring (25.9 vs. 30%; P = 0.04792).

CONCLUSION

The survey demonstrates important similarities as well as substantial differences regarding most of the aspects evaluated. Efforts to implement adherence to guidelines will be endorsed in Italy.

Comparison of Usefulness of Cardiac Resynchronization Therapy in Patients With Type 1 Myotonic Dystrophy With Versus Without Left Bundle Branch Block

Patients with type 1 myotonic dystrophy show reduced left ventricular systolic function in the presence of left bundle branch block due to electromechanical dys-synchrony. Our prospective study tracked a cohort of 64 type 1 myotonic dystrophy patients that demonstrated a high burden of atrial and ventricular arrhythmias and conduction delays. Of these patients, 12 (19%) patients had left bundle branch block, which was associated with reduced left ventricular systolic function. Eight of these patients received cardiac resynchronization therapy devices resulting in reduction of median QRS complex duration from 173 to 166 ms (p = 0.04), and improvement in median left ventricular ejection fraction from 37% to 46% (p = 0.007). In conclusion, cardiac resynchronization therapy device therapy is both feasible and effective in treating advanced cardiac disease in this vulnerable group of patients by improving left ventricular function.

[Active cardiac implantable electronic devices: What is possible in ambulatory health care in 2017?]

Telemonitoring (TM) features are implemented in nearly all cardiac implantable electronic devices (CIEDs) that have recently been released to the market. In combination with pacemakers, defibrillators and systems for cardiac resynchronization it is a safe and efficient method for routine technical aftercare of the devices as well as for monitoring heart failure and arrhythmias. Using TM has the potential to optimize patient care with regard to economic, clinical and safety aspects. Despite the good availability of existing data and clear recommendations of the responsible scientific societies, it is often seen as an isolated solution which is not fully integrated into standard care, although it has its own EBM number for implantable cardioverter-defibrillators and cardiac resynchronization therapy systems. The reasons are not only the unsatisfactory reimbursement of costs, different IT structures and the borders between clinics and medical practices, but also acceptance problems of physicians and legal aspects. The compensation of cardiac pacemakers and 'event recorders' is unsolved. TM provides the prospect for optimal and cross-sectoral patient care. Furthermore it has the potential to become the standard method for the care for patients with a CIED.

Pharmacological treatment changes of chronic heart failure during cardiac resynchronization therapy: A 1-year follow-up study

BACKGROUND

Cardiac resynchronization therapy (CRT) is associated with improved morbidity and mortality in patients with chronic heart failure (HF) on optimal medical therapy. We aimed to evaluate changes of medical therapy during CRT and its influence on the CRT response.

METHODS

We evaluated 85 HF patients' pharmacological treatment changes during 1-year follow-up of CRT. Statistical analysis was performed using IBM SPSS statistical software (SPSS v.21.0 for Mac OS X).

RESULTS

Beta-blockers (BAB) were used in 81.2% of patients before CRT, and consumption increased after CRT implantation (96.5% at 1-year follow-up visit) (p<0.002). Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) consumption and dose didn't significantly change statistically during the study. 55.3% of patients were taking spironolactone before CRT, and this number increased at discharge till 76.5% (p<0.001) and till 70.6% (p=0.01) at 1-year follow-up visit. The average dose of spironolactone during the study significantly decreased statistically. The use of diuretics was higher after CRT device implantation, compared with the period before CRT 80% to 84.7% (p<0.001), but torasemide dose hadn't significantly changed statistically and remained almost the same. Cardiovascular medication consumption was significantly lower before CRT, compared with discharge (p<0.001) and follow-up (p<0.001) periods. However, no statistically significant relation between pharmacological treatment and echocardiographic response was found.

CONCLUSIONS

The present study confirmed that pharmacological treatment has changed during the period before and after CRT. But no statistically significant relation between pharmacological treatment and echocardiographic response was found.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

National Trends in the Use of Cardiac Resynchronization Therapy With or Without Implantable Cardioverter-Defibrillator

BACKGROUND

Candidates for cardiac resynchronization therapy (CRT) receive either a biventricular pacemaker or a biventricular pacemaker with an implantable cardioverter-defibrillator (CRT-D). Optimal device selection remains challenging because the benefit of implantable cardioverter-defibrillator therapy may not be uniform, particularly in patients at competing risk of nonsudden death.

METHODS AND RESULTS

In this serial cross-sectional study using the National Inpatient Sample database, we identified 311,086 admissions associated with CRT implant between 2006 to 2012. CRT-D was the most common device type (86.1%), including in patients ≥ 75 years of age with ≥ 5 Elixhauser comorbidities (75.5%). Multivariate predictors of CRT-D implant included demographic, clinical, and geographic factors: prior ventricular arrhythmia (rate ratio [RR], 1.14; 95% CI, 1.13-1.14), ischemic heart disease (RR, 1.11; 95% CI, 1.10-1.11), male sex (RR, 1.10; 95% CI, 1.09-1.10), black race (RR, 1.06; 95% CI: 1.04-1.07), and Northeast geographic region (RR, 1.06; 95% CI, 1.04-1.09). There was significant interhospital variation in the use of CRT-D (10-90 percentile range, 72.9%-98.0% CRT-D).

CONCLUSIONS

The majority of patients in this contemporary US cohort underwent implantation of CRT-D. Predictors of CRT-D implant included demographic, clinical, and geographic factors. In patient subgroups predicted to have an attenuated benefit from implantable cardioverter-defibrillator therapy (older adults with multiple comorbidities), CRT-D remained the dominant device type. An improved understanding of the determinants of device selection may aid in decision making and ultimately better align patient risk with device benefit at the time of CRT implantation.

Newer Echocardiographic Techniques in Cardiac Resynchronization Therapy

Echocardiographic imaging plays a major role in patient selection for cardiac resynchronization therapy (CRT). One-third of patients do not respond; there is interest in advanced echocardiographic imaging to improve response. Current guidelines favor CRT for patients with electrocardiographic (ECG) QRS width of 150 milliseconds or greater and left bundle branch block. ECG criteria are imperfect; there is interest in advanced echocardiographic imaging to improve patient selection. This discussion focuses on newer echocardiographic methods to improve patient selection, improve delivery, and identify patients at risk for poor outcomes and serious ventricular arrhythmias.

Understanding Heart Failure

Heart failure (HF) is a growing global health concern that affects more than 20 million people worldwide. With an ever-growing segment of the population over the age of 65, the prevalence of HF and its associated costs are expected to increase exponentially over the next decade. Advances in the understanding of the pathophysiology and treatment of HF have resulted in the ability to enhance both the quantity and the quality of life of patients with HF. This article reviews the current understanding of the pathophysiology, cause, classification, and treatment of HF and describes areas of uncertainty that demand future study.

Quantification of survival gain from cardiac resynchronization therapy: nonlinear growth with time, and greater gain in low-risk patients, make raw trial data an underestimate of real-world behavior

OBJECTIVES

The goal of this study was to examine the impact of calculation-window duration on lifespan gain (as observed in trials) and on who gains most.

BACKGROUND

The landmark trials of biventricular pacing (cardiac resynchronization therapy [CRT]) typically ran for <1 device battery life, and they may therefore underestimate lifespan benefit over longer durations.

METHODS

We conducted a meta-analysis of biventricular pacing trials to calculate lifespan gained: first, within the duration of randomized controlled trial data up to 2 years; second, over a 5-year typical battery life; and third, over >1 battery life. Importantly, we applied the Gompertz method for age-related increase in mortality from non-CRT-preventable causes.

RESULTS

Five landmark trials (COMPANION [Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure], CARE-HF (CArdiac REsynchronization-Heart Failure), MADIT-CRT [Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy], REVERSE [Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction], RAFT (Resynchronization-Defibrillation for Ambulatory Heart Failure)) provided data for 2 years (6,561 patients), with an average hazard ratio of 0.71. Lifespan gained across all trials increased nonlinearly with time from 0.1 month at 1 year, to 0.5 month at 2 years, and a projected 6.5 months at 5 years (65 times more than at 1 year). After multiple devices, it reached 14 months, involving on average 1.6 devices (i.e., 8.8 months per device implanted). Moreover, while over a short window (e.g., 2 years), lower-mortality patients may gain less than higher-mortality patients (1.4 vs. 2.3 months), their positions reverse by 15 years (16.0 vs. 13.7 months).

CONCLUSIONS

Lifespan gain from biventricular pacing rises nonlinearly with time. Early on, higher-risk patients exhibit more gain, but later, lower-risk patients exhibit more gain. Quantifying gain over less than a patient's lifetime underestimates lifespan gain. Over the first 1 or 2 years, lower-risk patients may seem to gain less, although they may ultimately be the ones who gain the most.

Noncompaction cardiomyopathy is associated with mechanical dyssynchrony: a potential underlying mechanism for favorable response to cardiac resynchronization therapy

BACKGROUND

The aim of this study was to assess the presence of evidence of ventricular mechanical dyssynchrony in patients with isolated left ventricular noncompaction cardiomyopathy (IVNC) and the potential usefulness of cardiac resynchronization therapy (CRT) in those patients.

METHODS AND RESULTS

We studied 25 patients consecutively diagnosed with IVNC and a control group of 50 patients with dilated cardiomyopathy of different etiologies. Mechanical dyssynchrony was assessed by echocardiography by the presence of a septal flash, the time from peak septal to posterior wall displacement, and the time from septal to lateral wall peak systolic velocity. Among the patients with IVNC, 9 received CRT and were followed at 12 months. Overall, dyssynchrony parameters were significantly more frequent in IVNC, regardless of QRS duration. All 9 IVNC patients treated with CRT showed a septal flash, and a favorable response was observed in 8/9 patients (89%) regardless of QRS width.

CONCLUSIONS

The presence of mechanical dyssynchrony, amenable to correction with CRT, is common in patients with IVNC, independently from QRS width. This might be related to altered electrical endocardial activation associated with abnormal myocardium and could be the justification for the high response rate to CRT observed in these patients.

[Cardiac resynchronization: past, present and future]

Growing interest in dyssynchrony and cardiac resynchronisation therapy (CRT) has opened the way for new hemodynamic indications of cardiac stimulation. French investigators have played a key role in the formulation of new concepts based on clinical observation, as well as the development of resynchronisation devices in collaboration with industry, and their clinical evaluation. This review summarizes recent knowledge and perspectives pertaining to atrial, atrioventricular (AV) and ventricular dyssynchrony and resynchronisation. Some of these concepts have been validated by robust clinical evidence, on which scientific recommendations have been based. Others have been less successful but probably merit further attention.

[Electrical therapy for heart failure. Perspectives for 2011]

Implantable defibrillators (ICDs) and cardiac resynchronization therapy (CRT) represent established treatments for heart failure with positive results from clinical trials. However, for daily practice, several questions on the optimal use remain (e.g., patient selection, imaging, pacing sites). In addition, new treatment options which attempt to improve heart failure by modulating cellular calcium handling and autonomic dysbalance have recently been developed. For cardiac contractility modulation, initial results from randomized trials have been published. At present, the use of vagal stimulation is also being studied in clinical trials in Germany. New approaches refer to stimulation of sympathetic ganglia in the coronary sinus and left ventricular multisite pacing by ultrasound, but are still in the stage of acute testing.

[Vagus stimulation. Mechanisms and current clinical importance in heart failure]

Increased sympathetic activity and reduced vagal activity are associated with increased mortality both after myocardial infarction and in heart failure; furthermore, vagal withdrawal has been documented to precede acute decompensation. Experimental studies indicate that increased parasympathetic activity by means of vagal stimulation may reduce mortality in animal models of post-infarction sudden cardiac death and of chronic heart failure. Initial clinical results demonstrate that chronic vagus nerve stimulation in heart failure patients with severe systolic dysfunction appears to be safe and tolerable and may improve quality of life, submaximal exercise capacity, and LV function. Vagus nerve stimulation derives these potential clinical benefits from multiple mechanisms of action. These include reduced heart rate, restoration of heart rate variability and baroreflex sensitivity, suppression of pro-inflammatory cytokines, and antiarrhythmic effects.

[Cardiac resynchronization in narrow QRS and less affected exercise capacity]

Cardiac resynchronization (CRT) through atrio-biventricular pacemaker therapy is now a well established treatment option for severely symptomatic patients with advanced systolic heart failure (HF) and intraventricular conduction delay, especially left bundle branch block. The purpose of this article is to address possible applications of biventricular pacing beyond the classical CRT indication. In particular, a summary is given of available information on CRT in patients with symptomatic systolic HF, but narrow QRS complex, and those with wide QRS, but less pronounced or even absent clinical HF signs.

[Technical innovations and limitation in cardiac electrotherapy]

Coronary sinus (CS) lead positioning is one of the main determinants of cardiac resynchronization therapy (CRT). The implantation of the CS lead is faced with several technical difficulties that may prevent the achievement of a stable position and good performance of the CS lead without phrenic nerve stimulation (PNS). New developments in catheter and lead technology to overcome these difficulties are presented.

Cardiac resynchronization therapy: current trends and future directions

Despite the clear cut indications for cardiac resynchronization therapy (CRT) laid down by guideline forming bodies, there are numerous unresolved issues. This review article primarily focuses on the current trends in CRT and the challenges encountered in patient selection, procedure related and postimplantation patient management issues. The high rate of non-response to CRT warrants a critical appraisal of the patient selection criteria, with the role of QRS duration and use of imaging to quantify ventricular dyssynchrony being the major points of discussion. Likewise the role of CRT in relatively asymptomatic heart failure patients, those with atrial fibrillation and the benefits of providing an implantable cardioverter defibrillator backup to all CRT devices has yet to be clearly defined. The development of effective and minimally invasive surgical techniques, dependable and reproducible means for optimal pacing site localization and comparative trials on superior mode of lead positioning, pacing sites and optimized CRT programming encompassing diverse patient populations would further advance current standards of CRT. Innovative approaches to resolve these controversies and future goal directed research is needed. Development of novel, comprehensive prediction tools to identify responders to CRT and the possibility of 'leadless' pacing would be interesting futuristic prospects.

[Optimized CRT programming: relevance and practical application]

Cardiac resynchronization therapy (CRT) can result in significant clinical improvement in patients with congestive heart failure. Non-response to CRT might be attributable to suboptimal programming. Follow-up has to ensure effective left ventricular (LV) stimulation at rest and also sufficient exercise-dependent atrial rates. Rate adaptive pacing is required in case of chronotropic incompetence. Specific algorithms may help to restore biventricular pacing or the enhance biventricular pacing rate when intrinsic AV conduction occurs, e.g., during intermittent atrial fibrillation. An individual adaptation of the AV interval is essential to achieve maximal benefit from resynchronization. Optimized AV interval programming synchronizes atrial and ventricular contraction, maximizing the atrial contribution to LV diastolic filling and preventing presystolic mitral regurgitation. Interventricular synchrony and LV contraction might be further harmonized by VV interval adaptation, although the impact of VV optimization on CRT outcome is still under debate. Non-invasive methods of AV and VV interval optimization by electro- and echocardiography are discussed.