Cardiac resynchronization therapy outcomes in patients under nonoptimal medical therapy

Information-Theoretic Analysis of Cardio-Respiratory Interactions in Heart Failure Patients: Effects of Arrhythmias and Cardiac Resynchronization Therapy

The properties of cardio-respiratory coupling (CRC) are affected by various pathological conditions related to the cardiovascular and/or respiratory systems. In heart failure, one of the most common cardiac pathological conditions, the degree of CRC changes primarily depend on the type of heart-rhythm alterations. In this work, we investigated CRC in heart-failure patients, applying measures from information theory, i.e., Granger Causality (GC), Transfer Entropy (TE) and Cross Entropy (CE), to quantify the directed coupling and causality between cardiac (RR interval) and respiratory (Resp) time series. Patients were divided into three groups depending on their heart rhythm (sinus rhythm and presence of low/high number of ventricular extrasystoles) and were studied also after cardiac resynchronization therapy (CRT), distinguishing responders and non-responders to the therapy. The information-theoretic analysis of bidirectional cardio-respiratory interactions in HF patients revealed the strong effect of nonlinear components in the RR (high number of ventricular extrasystoles) and in the Resp time series (respiratory sinus arrhythmia) as well as in their causal interactions. We showed that GC as a linear model measure is not sensitive to both nonlinear components and only model free measures as TE and CE may quantify them. CRT responders mainly exhibit unchanged asymmetry in the TE values, with statistically significant dominance of the information flow from Resp to RR over the opposite flow from RR to Resp, before and after CRT. In non-responders this asymmetry was statistically significant only after CRT. Our results indicate that the success of CRT is related to corresponding information transfer between the cardiac and respiratory signal quantified at baseline measurements, which could contribute to a better selection of patients for this type of therapy.

Cardiac contractility modulation in heart failure with reduced ejection fraction treatment

Heart failure with reduced left ventricular ejection fraction (LV EF) (HFrEF) is a significant issue of health care due to increasing indexes of morbidity and mortality. The emergence of a number of drugs and implantable devices for the treatment of HFrEF has allowed improvement of patients’ well-being and prognosis. However, high mortality and recurrent decompensated heart failure remain a substantial issue and stimulate the search for new methods of CHF treatment. Cardiac contractility modulation (CCM) is a method of managing patients with HFrEF. Available data from randomized clinical trials (RCT) indicate the efficacy of CCM in improvement of patients’ well-being and quality of life. The question remains open: what effect does CCM have on LV reverse remodeling? Experimental data and results of observational studies suggest a possibility of reverse remodeling by CCM; however, this has not been confirmed in RCT. Also, it remains unclear how CCM influences the frequency of hospitalizations for decompensated heart failure and the death rate of patients with HFrEF. Results of both RCTs and observational studies have shown a moderate improvement of quality of life associated with CCM. Furthermore, RCTs have not found any increase in LV EF due to the therapy, nor has a meta-analysis of RCTs revealed any improvement of the prognosis associated with CCM.  Further RCTs are needed to evaluate the effect of CCM on reverse remodeling, survival rate, and to determine the place of CCM in the treatment of patients with CHF.

The European Society of Cardiology Cardiac Resynchronization Therapy Survey II: A comparison of cardiac resynchronization therapy implantation practice in Europe and France

BACKGROUND

The first European Cardiac Resynchronization Therapy (CRT) Survey, conducted in 2008-2009, showed considerable variations in guideline adherence and implantation practice. A second prospective survey (CRT Survey II) was then performed to describe contemporary clinical practice regarding CRT among 42 European countries.

AIM

To compare the characteristics of French CRT recipients with the overall European population of CRT Survey II.

METHODS

Demographic and procedural data from French centres recruiting all consecutive patients undergoing either de novo CRT implantation or an upgrade to a CRT system were collected and compared with data from the European population.

RESULTS

A total of 11,088 patients were enrolled in CRT Survey II, 754 of whom were recruited in France. French patients were older (44.7% aged≥75 years vs 31.1% in the European group), had less severe heart failure symptoms, a higher baseline left ventricular ejection fraction and fewer co-morbidities. Additionally, French patients had a shorter intrinsic QRS duration (19.1% had a QRS<130ms vs 12.3% in the European cohort). Successful implantation rates were similar, but procedural and fluoroscopy times were shorter in France. French patients were more likely to receive a CRT pacemaker than European patients overall. Of note, antibiotic prophylaxis was reported to be administered less frequently in France, and a higher rate of early device-related infection was observed. Importantly, French patients were less likely to receive optimal drugs for treating heart failure at hospital discharge.

CONCLUSION

This study highlights contemporary clinical practice in France, and describes substantial differences in patient selection, implantation procedure and outcomes compared with the other European countries participating in CRT Survey II.