Catheter ablation of repetitive ventricular tachycardia in patients with ischemic heart disease – our experience 257
IzvIrnI znanstvenI članek
idzdrav vestn | julij – avgust 2017 | letnik 86
Department of 
Cardiology, Division 
of internal medicine, 
University Medical Centre 
Ljubljana, Ljubljana
Korespondenca/
Correspondence:
Matjaž Šinkovec,  
e: matjaz.sinkovec@kclj.si
Ključne besede:
prekatna tahikardija; 
koronarna 
bolezen; ishemična 
kardiomiopatija; 
radiofrekvenčna ablacija; 
katetrska ablacija; 
klinični izid
Key words:
ventricular tachycardia; 
coronary artery 
disease; ischaemic 
cardiomyopathy; 
radiofrequency ablation; 
catheter ablation; clinical 
outcome
Citirajte kot/Cite as:
zdrav vestn. 2016;  
85:257–65.
Prispelo: 4. 8. 2015 
sprejeto: 16. 1. 2017
srce in ožiljeIzvirni znanstveni članek
Catheter ablation of repetitive ventricular 
tachycardia in patients with ischemic heart 
disease – our experience
Katetrska ablacija ponavljajoče se prekatne tahikardije 
pri bolnikih z ishemično boleznijo srca – naše izkušnje
Matjaž Šinkovec, Bor antolič, luka klemen, andrej Pernat
Abstract
Background: Ventricular tachycardia (VT) poses a significant risk for sudden death and heart fail-
ure exacerbation in patients with ischemic heart disease. Catheter-based radiofrequency ablation is 
the last treatment option for patients with frequent VT recurrences despite antiarrhythmic drugs. 
The aim was to present our retrospective catheter ablation data in this group of patients.
Patients and methods: The majority of 34 patients, who underwent percutaneous endocardial 
radiofrequency catheter ablation, were male, median age 67.5 years, who presented with electrical 
storm, had underlying cardiomyopathy after remote inferior wall myocardial infarction and preced-
ing myocardial revascularization procedure, and had been implanted with cardioverter-defibrillator 
(ICD). Two ablation methods were used: linear ablation and/or scar homogenization. Acute ablation 
success (non-inducibility of any VT) was achieved in 59 % of procedures. VT could not be inter-
rupted in 2 (6 %) patients. Pericardial tamponade that needed surgical intervention occurred in one 
procedure (2 %), and was related to inadvertent perforation of the right ventricular apex with a di-
agnostic catheter. Seven (20 %) patients died and additional 3 were lost from the median of 31 (6–151, 
rank) months of follow-up. No late VT recurrences were demonstrated in 20 (59 %) patients, and rare 
in 4 (12 %). Overall, the ablation procedure was successful in 71 % of patients.
Conclusion: Catheter ablation gave very good long-term clinical result in about two-thirds of our 
patients with ischaemic cardiomyopathy and frequent VT recurrences. Catheter ablation, preferably 
with scar homogenization approach, should be considered early to reduce the number of VT epi-
sodes and ICD discharges.
Izvleček
Izhodišča: Pri bolnikih z ishemično boleznijo srca je prekatna tahikardija (VT) pomemben dejavnik 
tveganja za nenadno smrt ali poslabšanje srčnega popuščanja. Katetrska radiofrekvenčna ablacija 
je zadnja možnost za bolnike s pogostimi napadi VT, pri katerih zdravljenje z antiaritmiki ni učin-
kovito. Namen prispevka je predstaviti naše retrospektivne rezultate katetrske ablacije VT pri teh 
bolnikih.
Pacienti in metode: Večina od 34 bolnikov, pri katerih smo opravili perkutano endokardno radiofre-
kvenčno katetrsko ablacijo, so bili moški mediane starosti 67,5 let, ki so imeli ob sprejemu električni 
vihar in kardiomiopatijo po starem spodnjestenskem srčnem infarktu. Večina je že imela opravljen 
revaskularizaciski poseg in vsajen kardioverter defibrilator (ICD). Ablacijo smo opravili na dva nači-
na – z linijskimi ablacijami in/ali s homogenizacijo brazgotine. Akutni ablacijski uspeh (neizzivnost 
katere koli VT) smo dosegli pri 59 % posegov. Pri 2 (6 %) bolnikih nam z ablacijo ni uspelo prekiniti 
VT. Tamponada, ki je zahtevala kirurško intervencijo, je nastala pri enem posegu (2 %) in je bila pov-
258 zdrav vestn | julij – avgust 2017 | letnik 86
srCe In ožIlje
zročena z diagnostičnim katetrom v desnem ventriklu. V 31 (6–151) mesecih spremljanja (mediana 
in rang) je umrlo 7 bolnikov (20 %) in 3 (9 %) se niso več oglasili v ambulanti. Pri 20 (59 %) bolnikih 
nismo beležili poznih recidivov VT, pri 4 (12 %) pa redke. Ablacijski poseg je bil torej uspešen pri 71 % 
naših bolnikov.
Zaključki: Pri dveh tretjinah naših bolnikov z ishemično kardiomiopatijo in pogostimi napadi VT 
smo dosegli s katetrsko ablacijo zelo dober dolgoročen klinični rezultat. Zato s posegom ne smemo 
odlašati, saj le na tak način lahko učinkovito preprečimo ponovne napade VT in proženje ICD. Pred-
nost ima metoda homogenizacije brazgotine.
1. Introduction
Ventricular tachyarrhythmias (VA) 
pose a significant risk for sudden death 
and heart failure exacerbation in pati-
ents with ischemic heart disease (IHD). 
One-third of deaths after myocardial 
infarction (MI) is caused by VA. Survi-
val of these patients improved conside-
rably after introduction of implantable 
cardioverter-defibrillators (ICDs)  (1). 
However, ICD shocks are painful, cause 
anxiety, depression, and more visits to 
emergency department–all resulting in 
a low quality of life. Almost one-fourth 
of patients experienced an ICD dischar-
ge after 5 years of follow-up in the AL-
TITUDE registry. In addition, frequent 
ICD discharges may in itself increase 
mortality  (2). Beta-blocking drugs and 
amiodarone reduced the incidence of 
ventricular tachycardia (VT) in some 
patients, however amiodarone is toxic 
and was withdrawn in almost one-quar-
ter of patients (3).
Catheter-based radiofrequency (RF) 
ablation is currently treatment of choice 
for patients with structural heart disease 
and frequent VT  (4,5). In addition, the 
new generation of 3-D electro-anatomi-
cal mapping systems have substantially 
improved ablation results  (5,6). These 
systems enable accurate heart chamber 
anatomical reconstruction, reproduci-
ble delineation of normal myocardium 
from the scar, based on electrogram am-
plitude, accurate determination of VT 
activation sequence, as well as reliable 
navigation and positioning of ablation/
mapping and diagnostic catheters, redu-
cing the need for fluoroscopy (Figure 1). 
With successful ablation procedure there 
are less ICD discharges, less hospitaliza-
tions, better quality of life, and possibly 
improved survival (6,7).
The aim was to present our retrospec-
tive catheter VT ablation results in pati-
ents with IHD.
2. Patients and methods
From a cohort of patients treated at 
our institution from January 2000 to 
December 2014 for recurrent sympto-
matic VA or frequent ICD shocks despite 
amiodarone and beta-blocking drug tre-
atment, patients with IHD were selected 
in whom a catheter RF ablation proce-
dure was performed. In addition to left 
ventricular thrombus, acute triggers for 
VA, such as ischemia, heart failure not 
caused by VT, infection, electrolyte or 
acid-base imbalance, and stroke, had to 
be excluded before the procedure. The-
refore, coronary angiogram and echo-
cardiogram were performed in all. The 
SPECT scan, gadolinium-enhanced MR 
scan, and CT were performed if feasible. 
A 12-lead ECG of clinical VT was acqui-
red if available. All patients or relatives 
provided an informed consent before 
the procedure.
Ablation procedure was usually per-
formed in the conscious-sedated pati-
Catheter ablation of repetitive ventricular tachycardia in patients with ischemic heart disease – our experience 259
IzvIrnI znanstvenI članek
ents (fentanyl, midazolam or propofol), 
anticoagulated with unfractionated he-
parin – activated coagulation time 300–
400 s –, and with invasively monitored 
arterial pressure. The 3-D electro-anato-
mical mapping system (CARTO, Biosen-
se-Webster), irrigated-tip RF ablation 
catheter–with retrograde or trans-septal 
approach – and fixed or steerable long 
sheaths were used. The ablation strate-
gy evolved over time. At the beginning, 
a »linear ablation« approach was used. 
Linear lesions were performed between 
the low-voltage areas and to the mitral 
annulus, or around and across low-vol-
tage areas, particularly near the VT exit 
sites. Later on, a »scar homogenization or 
scar de-channelling« approach was im-
plemented (Figure 1). A dense voltage-
-mapping during sinus rhythm for sub-
strate characterization was performed 
and RF ablation of all local electrograms 
(EGs) within the low-voltage area, whi-
ch characterize a viable myocardium 
within the scar, was done. The VT in-
duction attempt with programmed sti-
mulation was performed only at the end 
of the procedure to assess the treatment 
result. Low-voltage area was defined for 
EGs less than 1.5 mV. The pace-mapping 
was performed at low-voltage areas to 
define VT exit sites and conducting 
channels according to QRS morphology 
and stimulus-to-QRS time. Sustained or 
non-sustained clinical VT is frequently 
induced at this point. The entrainment 
mapping was quickly done to define 
slow-conducting zone in patients with 
haemodynamically stable VT. RF appli-
cations (35–50W, 17–30 mL/min) were 
targeting all sharp fragmented EGs at 
sites with long pace-to-QRS time (> 50 
ms) or diastolic EGs during VT. The 
ablation endpoint was disappearance of 
all local EGs in the low-voltage area with 
loss of capture at 10 mA, 2 ms, providing 
a good catheter-tissue contact  (8). The 
Table 1: Clinical characteristics and catheter ablation results in our patients 
with ischemic heart disease and recurrent ventricular tachycardia.
Patients (n) 34
age (median, range) 67.5 years (53–84)
Men (n) 31 (91 %)
electrical storm* 23 (68 %)
slow vt** 16 (47 %)
MI in the past 30 (88 %)
-infero-posterolateral scar 24 (80 %)
lveF < 45 % 27 (79 %)
ICD 23 (68 %)
Myocardial revascularization in the past 25 (73 %)
arterial hypertension 23 (68 %)
Chronic kidney disease II-Iv*** 8 (24 %)
atrial fibrillation/flutter 7 (21 %)
Peripheral vascular disease 5 (15 %)
Diabetes (n) 4 (12 %)
Ablation procedure results (n) 44
- success 19 (59 %)
- partial success 8 (25 %)
- failure 5 (16 %)
- not tested 12 (28 %)
DAP (µGym2) median (range) 667 (155–5182)
Fluoroscopy (min) x ± sD (range) 21 ± 14 (8–68)
Procedure time**** (min) x ± sD (range) 240 ± 52 (165–345)
tamponade 1 (2 %)
Follow-up results (median, range) 31 months (6–151)
- no vt recurrence 20 (59 %)
- rare late vt recurrences 4 (12 %)
- death up-to 6 months 5 and 1 + 
- all deaths 7 and 3 + 
*≥ 3 separate episodes of ventricular tachyarrhythmia in 24 h, each requiring 
termination by ICD or other intervention; ** ≤ 140/min; ***glomerular filtration 
rate: 15–89 mL/min/1.73 m2; ****from punction to catheter withdrawal;+ 
absent after the last regular ICD visit; MI – myocardial infarction, LVEF – left 
ventricular ejection fraction, ICD – implantable cardioverter defibrillator, DAP – 
dose area product, AAD – antiarrhythmic drugs
260 zdrav vestn | julij – avgust 2017 | letnik 86
srCe In ožIlje
Figure 1: the »scar homogenization« or »scar de-channelling« ablation approach. radiofrequency 
catheter ablation lesions are tagged with dark red points on the red background of the low-voltage 
area. normal-voltage area is shown in purple. this approach seems more successful than former 
linear ablation approach. a sharp late local electrogram – an ablation target–is marked by an arrow. It 
represents muscle tissue within the scar that is activated late, after the Qrs complex seen above.
final step was programmed stimulation 
from the right ventricle and from the 
border of the ablated low-voltage area. A 
protocol 600/350/300/300 ms was used 
for VT induction. An acute success was 
defined as non-inducibility of any VT, 
partial success as non-inducibility of cli-
nical VT, and acute failure as inducibility 
of clinical VT. The long-term success was 
defined as no VT recurrence during the 
follow-up. A success with rare recurrences 
was defined as > 75 % reduction in VT re-
currences over the same period of time–
with or without antiarrhythmic medica-
tions, and other results were considered 
non-successful. The term electrical storm 
was defined as ≥ 3 separate episodes of 
VA in 24 h, each requiring termination 
by ICD or other intervention. Slow VT 
was defined at frequency < 140/min. The 
VT recurrence was defined as any VT 
of ≥ 30 s duration or VT with ICD in-
terrogation (anti-tachycardia pacing or 
discharge).
Descriptive statistics was used for 
data presentation.
3. Results
From 317 consecutive patients (202 
male, 64 %), structural heart disease was 
identified in 100 patients (31 %), 82 male 
(82 %). Out of these, the most prevalent 
underlying pathology was CAD (53 pa-
tients (53 %), 45 male (85 %)) followed 
by other cardiomyopathies (dilated–18, 
arrhythmogenic right ventricular–9, su-
spected myocarditis–6, congenital–5, 
hypertensive–4, valvular–4, and hyper-
trophic–1) (Figure 2).
Catheter ablation for sustained mo-
nomorphic VT was performed in 34/53 
patients (64 %) with CAD due to amioda-
rone and beta-blocking drug treatment 
Catheter ablation of repetitive ventricular tachycardia in patients with ischemic heart disease – our experience 261
IzvIrnI znanstvenI članek
Figure 2: Patients with structural heart disease (n = 100, male 82) from our 
cohort of patients with ventricular tachyarrhythmias. Ischaemic heart disease 
(IHD) is the most prevalent (53 %), followed by dilative cardiomyopathy (DCM) 
and arrhythmogenic right ventricular cardiomyopathy (aCM). among others 
are patients with suspected myocarditis, congenital disease, hypertensive 
cardiomyopathy, valvular cardiomyopathy, and hypertrophic cardiomyopathy.
failure or amiodarone withdrawal due to 
toxicity (Table 1). Significant comorbi-
dities were present in majority of them 
(Table 1). Myocardial revascularizati-
on procedures were performed in 25/34 
(73 %) patients–surgery in 15 (60 %) and 
percutaneous intervention in additional 
10 patients (40 %). Electrical storm and 
slow VT were the most frequent initial 
presentations. ICD was implanted befo-
re the first ablation procedure in 23/34 
patients (68 %) and in additional 8 after-
wards. Therefore, 91 % of patients were 
treated with ICDs during the follow-up. 
The majority of VT ablation procedures 
were performed over the last years (Fi-
gure 3).
Scar-related re-entry due to remo-
te myocardial infarction was the most 
frequent mechanism of VT seen in 30/34 
patients (88 %). Scar was located in the 
infero-posterolateral area of the left ven-
tricle in majority (24/30 patients, 80 %). 
Recurrent VA triggered by Purkinje-re-
lated or outflow-tract premature ventri-
cular complex-related VA was suspected 
in 4/34 patients (11 %).
The 3-D electro-anatomical mapping 
system (CARTO) was used in 39/44 
(89 %) of procedures. »Scar homogeni-
zation« approach was used in 27/44 pro-
cedures (61 %), »linear ablation« appro-
ach in 13/44 (30 %), and focal ablation in 
4/44 (9 %) procedures. In all, only endo-
cardial RF ablation was performed.
Acute success was tested at the end 
of the procedure in 32/44 procedures 
and the result was successful in 19/32 
procedures (59 %), partially success-
ful in 8/32 (25 %), and procedure failed 
in 5/32 (16 %). Testing was not perfor-
med in other 12 procedures because of 
hemodynamic instability and frequent 
electrical cardioversions/defibrillations 
during the procedure. There were no 
procedure-related deaths. A pericardial 
tamponade that needed surgical inter-
vention occurred in one procedure (2 %). 
It was related to diagnostic catheter per-
foration at the right ventricular apex in a 
patient on dual antiplatelet therapy. Data 
for minor vascular access complications 
or transient heart failure exacerbation 
were incomplete, but definitely below 
10 %. In 2/34 patients (6 %) incessant VT 
could not be terminated acutely (one pa-
tient died during the initial hospitalizati-
on and another after 2 months of follow-
-up, both due to uncontrollable slow VT 
with progression to heart failure).
Median (rank) follow-up time was 
31 months (6–151). Seven patients died 
and 3 did not come to regular out-pati-
ent visits after 4, 11 and 82 months. Five 
patients died during 6 months of follow-
-up (2 during initial hospitalization–one 
due to uncontrollable slow VT menti-
oned before, another in terminal heart 
failure; others after 1, 2, and 3 months, 
IHD
Legend:
DCM
ACM
other
262 zdrav vestn | julij – avgust 2017 | letnik 86
srCe In ožIlje
respectively). Other two patients died 
after 9, and 112 months of follow-up. No 
VT recurrences were documented after 
at least 6 months of follow-up in 20/34 
patients (59 %, 1 with 3 procedures and 3 
with 2 procedures) and rare VT episodes 
were documented in additional 4 (12 %; 
22, 24, 36 and 48 months after ablation). 
Ten patients are without antiarrhythmic 
drugs, 6 on amiodarone and ranolazine, 
6 on amiodarone, and 2 are on ranolazi-
ne alone. The majority of VT recurrences 
(75 %) were documented up-to 6 months 
after ablation procedure (Figure. 4).
4. Discussion
Our patients with IHD, in whom 
we performed endocardial RF catheter 
ablation for frequent VTs and ICD di-
scharges, were typically male in their 
sixties, with ICM after remote inferior 
wall MI, after myocardial revasculari-
zation procedure, and with implanted 
ICD. Two-thirds of them presented with 
electrical storm. This report represents a 
single-centre retrospective clinical expe-
rience.
The scar homogenization ablation 
approach that we adopted recently is 
promising. However, a prospective ran-
domized study is needed to provide the 
proof of scar homogenization superiori-
ty over the linear ablation approach. Ne-
vertheless, the success rate (clinical be-
nefit in 71 % of patients) and safety (one 
major complication in the series only) 
are acceptable and comparable to repor-
ted data from the world’s leading centres 
(Table 2)  (6,9-14). In another 13 studies 
with mean follow-up of 12 months or 
more, 50–88 % of patients were free of 
any VT, with 30–100 % continuing on 
previously ineffective antiarrhythmic 
medications (5). The efficacy of VT abla-
tion was also emphasized in a recent on-
0
2
4
6
8
10
12
14
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Figure 3: number of ventricular tachycardia (vt) catheter ablation procedures per year in patients with 
ischemic heart disease (UCC ljubljana). numbers have been increasing over the last few years.
Catheter ablation of repetitive ventricular tachycardia in patients with ischemic heart disease – our experience 263
IzvIrnI znanstvenI članek
-treatment analysis of the VTACH study 
in a similar group of patients as ours (7). 
VT ablation clearly prolonged time to 
recurrence of VA episodes and markedly 
decreased VA burden. In another recent 
report in patients with ICM, VT-free su-
rvival at 1-year follow-up was 57 % (15); 
almost identical result to ours.
The catheter ablation of VT is one 
of the most demanding interventional 
procedures in cardiology with additio-
nal safety risks for severely compromi-
sed patients. The prevalence of our VT 
ablation procedure complications are 
within the reported range. Procedure-
-related shock/death was reported in 
0–3 %, stroke in 0–2.7 %, and perforati-
on/tamponade in 0–2.7 %. Non-fatal mi-
nor complications occurred in 5–10 % of 
patients, including transient heart failure 
exacerbation, increase in mitral regurgi-
tation, conduction block, and vascular 
access complications. Mortality during 
different follow-up periods ranged from 
0 to 32 % (5).
After antiarrhythmic drug treatment 
failure, catheter-based irrigated-tip RF 
ablation remains the only reasonable 
treatment option. The use of novel 3-D 
electro-anatomical mapping systems are 
mandatory–for substrate characteriza-
tion, VT activation mapping, catheter 
navigation, and contact-force measure-
ments during ablation,–for a successful 
scar homogenization, which seems to be 
the most successful ablation approach. A 
novel high-density mapping technology 
is a particularly promising advancement 
in this regard. Non-inducibility of all VTs 
at the end of ablation procedure may be 
a good indicator for long-term ablation 
success, on top of the complete scar ho-
mogenization. Likewise, non-inducibi-
lity of all VTs was an independent pre-
dictor of VT recurrence in a recent study 
from Leipzig (15). However, this finding 
0
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Figure 4: number of patients with the first vt recurrence according to the month after ablation 
procedure. early recurrences are possibly associated with ablation procedure failure and late-ones are 
due to disease progression.
264 zdrav vestn | julij – avgust 2017 | letnik 86
srCe In ožIlje
was not confirmed by others, since the 
inducibility of VT at the time of cathe-
ter ablation had no impact on long-term 
freedom from VA (16). This may be the 
consequence of different study designs 
with different ablation and stimulation 
protocols and needs further clarification.
5. Conclusion
Catheter ablation, performed in an 
experienced centre, should be consi-
dered early to reduce episodes of re-
current VT and ICD shocks in patients 
with IHD, even when multiple and he-
modynamically intolerable VTs are pre-
sent, like during the electrical storm. 
Two-thirds of these patient are doing 
well long-term after the ablation pro-
cedure. Approaches to guiding ablation 
are now well defined. A 3-D electro-ana-
tomical mapping system is mandatory 
for substrate characterization and scar 
homogenization, which seems to be the 
most successful ablation strategy. Even 
in patients with multiple co-morbidities, 
procedure mortality and morbidity are 
acceptable. Our clinical experience is in 
compliance with the published recom-
mendations (5).
6. Acknowledgement
The catheter ablation strategy at 
our centre evolved over years with the 
growing experience, expertise, and 
knowledge in the field of clinical elec-
trophysiology. For that, we have to 
express a deep gratitude to our teacher 
Prof. Peter Rakovec. However, of the ut-
most importance was a creative team-
-work that bloomed in the last few ye-
Table 2: the comparing results of catheter vt ablation in patients with IHD from the world’s leading centres.
Study No 
of 
pts
EF 
(%)
Substrate Targeted 
VT
Mapping Acute 
success
Follow-
up 
(months)
Follow-
up 
success
Follow-
up 
Mortality
Morady F, 1993* (9) 15 27 ± 8 ICM stable vt 73 % 9 ± 3 80 % -
Della Bella P, 2002* (10) 124 - ICM stable vt 73 % 41.5** 75 % 12 %
kautzner j, 2003* (11) 28 28 ± 9 ICM all vt/
substrate
85 % 10 ± 6 78 % -
volkmeer M, 2006* (12) 47 30 ± 8 ICM Clinical 
and slow
vt/
substrate
95 % 25 ± 13 75 % -
Carbucicchio C, 2008* 
(13)
95 36 ± 
11
ICM (75 %) electrical 
storm
vt/
substrate
89 % 22 ± 13 66 % 16 %
stevenson WG, 2008*** 
(6)
231 25** ICM Clinical 
and slow
vt/
substrate
49 % 6** 53 % 18 %
tanner H, 2009*** (14) 63 30 ± 
13
ICM all vt/
substrate
81 % 12 ± 3 51 % 9 %
Šinkovec M, 2015* 34 35** ICM all /
electrical 
storm
vt/
substrate
59 % 31**
(> 6 
months)
71 % 29 %
(15 % 
up to 6 
months)
* singlecenter study; ** median; *** multicenter study; VT – ventricular tachycardia, CAD – coronary artery disease, EF – left 
ventricular ejection fraction, ICM – ischaemic cardiomyopathy
Catheter ablation of repetitive ventricular tachycardia in patients with ischemic heart disease – our experience 265
IzvIrnI znanstvenI članek
ars. Thus, we are sincerely grateful to all 
members of electrophysiology team for 
the dedicated and professional assistan-
ce, but above all, to Hinko Urbančič, Li-
dija Marinč, and Maj Kobe.
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