Blood circulation values in patients with cardiac resynchronization therapy during the first 6 months in different stimulated QRS complex duration classes

Introduction

About 2% of the population in developed countries suffer from chronic heart failure (CHF) (Writing Сommittee Members et al., 2013). Cardiac resynchronization therapy (CRT) becomes an alternative method of CHF treatment when medical therapy does not yield positive results. The aim of CRT is ventricular mechanical dyssynchrony correction with QRS complex duration shortening (Cleland J.G. et al., 2005; Daubert C. et al., 2009; Exner D.V., 2009; Stellbrink C., 2009).

Numerous studies have shown that the decrease of QRS complex duration in patients with CRT is associated with improvement of blood circulation values (Su Y. et al., 2009; Singh J.P. et al., 2011; Mehta S., Asirvatham S.J., 2012), and the increase of QRS complex duration is associated with their worsening (Bomb R. et al., 2013).

Purpose of this study — to assess functional blood circulation values in patients during the first 6 months of CRT in different stimulated QRS complex duration classes.

Materials and methods

We prospectively examined twenty nine patients (10 — females, 19 — males) with CRT at the department of ultrasound, clinical and instrumental diagnosis and minimally invasive technologies of SI «V.T. Zaitsev Institute of General and Emergency Surgery NAMS of Ukraine». Patients’ average age was 69±7 years. Indications for CRT were CHF of IIIV functional class (FC) by New York Heart Association (NYHA) Functional Classification, QRS complex duration >120 ms, left ventricular ejection fraction (LVEF) ≤ 35%. According to CRT technique CRT-P and CRT-D devices were implanted.

Spontaneous and induced rhythm ventricular contractions (VC), systolic blood pressure (SBP) and diastolic blood pressure (DBP), LVEF, end-diastolic (EDV) and end-systolic (ESV) volumes, interventricular septum (IVS), posterior wall (PW) thicknesses, left (LA) and right atriums (RA), right ventricular (RV) measurements were evaluated before treatment, in the early postoperative period (the 3^rd–5^th day) and 6 months after CRT-device implantation.

SBP and DBP were measured by Korotkov’s method according to the recommendations of the Association of Cardiologists of Ukraine for the prevention and treatment of hypertension with use of tonometer Microlife BP AG1-20 in clinostaze after 5 min rest. The measurement accuracy was 2 mm Hg.

Electrocardiography study (ECG) was performed with use of computer electrocardiograph «Cardiolab +2000». The stimulated QRS complex duration was measured in leads II, V₅, V₆ (the average of three consecutive complexes) with a choice of maximum value. Measurement accuracy proved to be 1 ms.

Patients were divided into three QRS complex duration classes in accordance to M. Haghjoo et al. (2008): 1 person — <119 ms (normal), 2 persons — 120–149 ms (extended) and >150 ms (significantly extended). Functional blood circulation values were defined in selected classes.

Echocardiography study was performed with use of ultrasound machine Toshiba Applio 400. LF, RF, RV measurements and IVS, PW thickness were measured. To calculate the EDV and ESV we used method of Simpson. LV EF was calculated using the formula:

Medication support of patients with CRT was provided with antiarrhythmic drugs (beta-blockers and amiodarone), renin-angiotensin-aldosterone inhibitors (RAAI) — angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists (ARA II), antithrombotic drugs (antiplatelet agents — acetylsalicylic acid (ASA), oral anticoagulants (AC) — warfarin or dabigatran), statins, and diuretics.

Data were brought into the Microsoft Excel base. For statistical results evaluation were used the parametric criteria (mean — M, standard deviation — sd). Comparing QRS duration complex classes on the observation stages was conducted on each separate functional blood circulation value using a non-parametric Mann — Whitney U-test. Probable results were determined at levels of reliability α=0.05.

Results and discussion

Table shows comparative characteristics of functional blood circulation values in patients within different QRS complex duration classes before implantation, in early postoperative period and 6 months later.

VC in all QRS complex duration classes did not come out from the physiological range at the all observation stages. SBP remained in the physiological range at the all observation stages in classes 1 and 2. SBP was initially increased in class 3, it was decreased and entered the physiological range in the early postoperative period. DBP in all QRS complex duration classes at all observation stages was within physiological range.

There was an increase of initially reduced LVEF in classes 2 and 3 QRS complex duration, starting with early postoperative period. In class 2 LVEF was increase by 19%, in class 3 — by 32% during 6 months. Increase of LVEF was provided initially by reducing enlarged ESV and EDV. ESV at 6 months of observation in class 2 was decreased by 28%, in class 3 — by 44%, EDV in class 2 was decreased by 20% and in class 3 — by 32%.

CRT has also contributed to reducing of LA size in all QRS complex duration classes in early postoperative period with preservation trends only in class 2 during the first 6 months of observation without change.

R. Bomb et al. found that in some patients with CRT, QRS complex duration could be increased that carries a poor clinical outcome, in that case functional blood circulation values are not improved, moreover they are changed for the worse (Bomb R. et al., 2013). In our group of patients, increasing of QRS complex duration was observed in no case, on the contrary, in some cases elongated or substantially elongated QRS complex duration class went to the normal, what can be attributed to the optimal placement of electrodes during implantation, as well as carefully selected drug therapy.

For purposeful study of functional blood circulation values in patients in different QRS complex duration classes in patients with CRT, S. Stavrakis et al. performed substantial meta-analysis, which included evaluation of several studies RAFT 2010, MADIT-CRT 2009, REVERSE 2008, CARE-HF 2005, COMPANION 2004 with 6,501 patients, including 4,437 patients with QRS complex duration ≥150 ms and 2, 064 patients with QRS complex duration <150 ms) (Stavrakis S. et al., 2012). It has been shown that the best results were achieved in patients with QRS complex duration ≥150 ms versus class QRS <150 ms. In our group of patients, this trend is confirmed.

Conclusions

Carefully executed CRT with high-quality selection of the electrode application point and adequate medical support can not only prevent the further extension, but also, in some cases, can shorten the duration of the extended baseline QRS complex with improving functional blood circulation values.

CRT with high-quality selection of the electrode application point and adequate medical support is an effective treatment in patients with CHF.

Regerding prospects for future research it seems appropriate to conduct further following-up this group of patients to assess the long-term changes in functional blood circulation values.

References

• Bomb R. Logan J., Madsen R. et al. (2013) Prolongation following cardiac resynchronization: incidence, predictors, and outcomes. J. Innov. Card. Rhythm Man., 4: 1346–1354.
• Cleland J.G., Daubert J.C., Erdmann E. et al. (2005) The effect of cardiac resynchronization on morbidity and mortality in heart failure. N. Engl. J. Med., 352(15): 1539–1549.
• Daubert C., Gold M.R., Abraham W.T. et al. (2009) REVERSE Study Group. Prevention of disease progression by cardiac resynchronization therapy in patients with asymptomatic or mildly symptomatic left ventricular dysfunction: Insights from the European cohort of the REVERSE (Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction) trial. J. Am. Coll. Cardiol., 54(20): 1837–1846.
• Exner D.V. (2009) Is it time to expand the use of cardiac resynchronization therapy to patients with mildly symptomatic heart failure? J. Am. Coll. Cardiol., 54(20): 1847–1849.
• Haghjoo M., Bagherzadeh A., Farahani M.M. et al. (2008) Significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure patients eligible for cardiac resynchronization: particular focus on patients with right bundle branch block with and without coexistent left-sided conduction defects. Europace, 10(5): 566–571.
• Mehta S., Asirvatham S.J. (2012) Rethinking QRS Duration as an indication for CRT. J. Cardiovasc. Electrophysiol., 23(2): 169–1671.
• Singh J.P., Klein H.U., Huang D.T. et al. (2011) Left ventricular lead position and clinical outcome in the multicenter automatic defibrillator implantation trial-cardiac resynchronization therapy (MADIT-CRT) trial. Circulation, 123(11): 1159–1166.
• Stavrakis S., Lazzara R., Thadani U. (2012) The benefit of cardiac resynchronization therapy and QRS duration: a meta-analysis. J. Cardiovasc. Electrophysiol., 23(2): 163–168.
• Stellbrink C. (2009) Cardiac resynchronisation therapy — how much mechanical dyssynchrony and cardiac imaging is necessary before device implantation? Dtsch. Med. Wochenschr., 134(15): 763–768.
• Su Y., Pan W., Gong X. et al. (2009) Relationships between paced QRS duration and left cardiac structures and function. Acta Cardiol., 64(2): 231–238.
• Writing Сommittee Members, Yancy C.W., Jessup M. et al. (2013) 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation. 128(16): e240–327.

Contacts:
Irene V. Shanina
Freedom Square, 4, Kharkiv, 61077, Ukraine
V.N. Karazin Kharkiv National University,
School of Medicine,
Internal Medicine Department
E-mail: [email protected]