CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 4, May 2012
AFRICA
191
Nebivolol therapy improves QTc and QTcd parameters in
heart failure patients
SM AKSOY, S CAY, G CAGIRCI, N SEN
Abstract
Aim:
It has previously been shown that
β
-blocker therapy
reduces QT dynamics in heart failure patients. The aim of
this study was to demonstrate this improvement with the
third-generation
β
-blocker, nebivolol.
Methods:
A total of 72 heart failure patients with systolic
dysfunction were included in the study. Corrected QT (QTc)
and QT dispersion (QTcd) were measured manually by two
independent observers at baseline and after nebivolol use (5
mg/day) in the first and third months of follow up.
Results:
Both QTc and QTcd were found to be significantly
reduced in the first (455.3
±
26.7 vs 441.2
±
25.7 ms,
p
<
0.001
for QTc, and 65.6
±
5.3 vs 58.2
±
5.6 ms,
p
=
0.001 for QTcd)
and third months (455.3
±
26.7 vs 436.0
±
28.7 ms,
p
<
0.001
for QTc, and 65.6
±
5.3 vs 56.0
±
6.2 ms,
p
<
0.001 for QTcd)
compared with baseline values.
Conclusion:
Nebivolol was associated with improved QT
dynamics in heart failure patients with systolic dysfunction.
Keywords:
improvement, nebivolol, QT dynamics
Submitted 18/2/10, accepted 30/8/11
Cardiovasc J Afr
2012;
23
: 191–193
DOI: 10.5830/CVJA-2011-046
Heart failure, both systolic and diastolic, is a clinical syndrome
with different treatment modalities and a poor prognosis,
especially in the advanced stages.
β
-blocker therapy, including
nebivolol, improves survival in these patients by modulating
several neurohormonal mechanisms.
1-4
Nebivolol is a selective
β
1
-blocker with vasodilatory
properties due to modulation of nitric oxide release, which
decreases peripheral vascular resistance.
5,6
In addition, it has
been demonstrated that in patients with hypertension, nebivolol
reduces QT dispersion and corrected QT interval (QTc) and
corrected QT dispersion (QTcd), which are indicators of the
heterogeneity of myocardial repolarisation and electrical
instability.
7
Abnormality of these parameters has been also found
to be associated with adverse cardiac events and mortality.
8
In the current study, we aimed to demonstrate the beneficial
effect of nebivolol on QTc and QTcd in patients with heart
failure with systolic dysfunction.
Methods
Consecutive
β
-blocker-naïve (no use during the four weeks
before study entry) systolic heart failure patients were selected
for the study. A total of 75 patients were possible candidates and
were included in the study. However, three were subsequently
excluded because of side effects of the drug. At the end of the
follow-up period, 72 patients taking the drug remained.
All the participants had depressed left ventricular ejection
fraction (
<
40%) as per the study protocol. Patients were
interviewed about any cardiovascular drug use, and NYHA
functional class was determined. Systolic and diastolic blood
pressure and heart rates were measured at the beginning of the
study and in the third month. Laboratory parameters including
serum electrolytes were assayed. Nebivolol 5 mg/day was started
in all patients and the same dose was continued throughout the
study period.
Patients with
β
-blocker use in the previous four weeks,
electrolyte abnormalities, any drug use prolonging QT
interval, coronary artery disease or acute coronary syndromes,
pacemakers, atrial fibrillation, and significant hepatic and renal
dysfunction were excluded from the study.
The electrocardiograms (ECG) were recorded after 10 minutes
of rest in the supine position, using 12 simultaneously recording
leads: three standard (DI, DII, DIII), three unipolar (aVR, aVL,
aVF) and six precordial (V1–V6), at a paper speed of 25 mm/s.
Readings were done manually by the same two cardiologists
blinded to the study. There is evidence that manual measurement
is superior to automatic measurement of QTd.
9,10
The QT interval was measured in each lead from the onset of
the QRS complex: the beginning of the Q wave to the terminal
inscription of the T wave in the lead with clearly identified
T-wave termination, or from the beginning of the R wave if the
Q wave was absent. The terminal inscription of the T wave was
determined as the return to the TP baseline. When a U wave
was present, the QT interval was measured to the nadir of the
curve between the T and U waves. The QTcd was defined as
the difference between the maximum and minimum of the QTc
intervals, measured in milliseconds in any of the measured ECG
leads.
Statistical analysis
Data were analysed with SPSS software version 15.0 for
Windows (SPSS Inc, Chicago, Illinois, USA). Continuous
variables are presented as mean
±
SD and categorical variables
as frequency and percentage. The Kolmogorov–Smirnov test
was applied to assess the distribution of continuous variables.
The Student’s
t
-test was used to compare normally distributed
continuous variables and the Mann–Whitney U-test for variables
Department of Anesthesiology, Diskapi Yildirim Beyazit
Education and Research Hospital, Ankara, Turkey
SM AKSOY, MD
Department of Cardiology, Yuksek Ihtisas Heart Education
and Research Hospital, Ankara, Turkey
S CAY, MD,
N SEN, MD
Department of Cardiology, Diskapi Yildirim Beyazit
Education and Research Hospital, Ankara, Turkey
G CAGIRCI, MD
