CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 3, April 2012
AFRICA
141
we compared TIC patients who had complete improvement,
with age and LVEF-matched control subjects with normal
echocardiograms, TIC patients showed a trend of greater LVIDd
dimensions, indicating persistence of adverse LV remodelling at
follow up. LA dimensions also remained significantly elevated
at follow up.
TIC patients with dilated ventricles at presentation were
more likely to have residual LV dilatation at follow up. This
observation stresses the importance of serial echocardiographic
measurements at follow up. The clinical importance is that
beta-blockers and renin–angiotensin system inhibitors should
probably be prescribed to all TIC patients with residual LV
dysfunction or dilated left ventricles at follow up, although data
to support this recommendation are limited.
Nerheim
et al.
reported five patientswith recurrent tachycardia,
which caused a rapid decline in LV function and development of
heart failure in all patients.
11
These patients had an abrupt fall
in LVEF within six months and reversed again within a similar
period. Since that initial observation, another study reported two
patients with recurrence of the tachycardia and TIC.
12
Notably,
these two patients had a very short period of symptoms from the
tachyarrhythmia (12 days, one day) to presentation. Our study
is the third report with recurrent tachycardias occurring in three
patients.
Patient 41 developed an impure TIC secondary to
an orthodromic AVRT with a previous inferior myocardial
infarction. The presenting LVEF was 21%. He was started on
metoprolol, enalapril and diuretics. At a three-week follow-
up visit, his symptoms had markedly improved, with a repeat
echocardiogram showing a LVEF of 51%, confirming a diagnosis
of TIC. Unfortunately, he defaulted on medical therapy and
re-presented with recurrence of the AVRT four months later. An
echocardiogram confirmed that his LV function had deteriorated
to a LVEF of 35%. His accessory pathway was successfully
ablated. At two years’ follow up, he reported no recurrences
of palpitations or AVRT. His last follow-up echocardiogram
showed a LVEF of 48%. This case highlights the observation
that recurrence of tachycardia may lead to a rapid decline in LV
function.
Patient 4 developed a pure TIC secondary to two different
ATs, with a presenting LVEF of 16%. Only one of the ATs could
be ablated. Nevertheless, the LVEF improved to 61% one year
after ablation. The patient was continued on anti-arrhythmia
therapy. Eighteen months later, the first AT recurred, with
deterioration in LVEF to 50% and mean heart rates on Holter of
119 beats/min. Pharmacological rhythm control was preferred.
At the last follow up, the LVEF had improved to 53%.
Patient 23 developed a pure TIC secondary to rapid AFL
with a presenting LVEF of 40%. While awaiting ablation of the
AFL, the LVEF improved to 50% with pharmacological rate
control. AFL ablation was unsuccessful. His AFL persisted and
pharmacological AFL rate control (mean heart rates 97 beats/
min) was noted to be suboptimal. This led to a slow progressive
decline in LV function over three years (LVEF 32%). Successful
AFL ablation led to improvement in LV function to a LVEF of
53% five months after ablation.
The long-term prognosis of TIC has not been established.
Nerheim
et al
. documented three TIC patients who had recovered
LV function and had sudden cardiac death.
11
A study by Fujino
et al.
13
showed that cardiac death and recurrent hospitalisations
were significantly less in the TIC group than the DCMO group.
In our study, 33 pure TIC patients were followed up for a
mean period of 6.8 (range 1–19) years. Twenty patients were
confirmed alive at the time of writing this article. There were
three confirmed deaths. The nature of one death was due to
a cholangiocarcinoma. The causes of death in the other two
patients could not be determined from clinical records. Ten out of
33 patients could not be contacted. Of the 10 patients, four were
discharged in a stable condition from the cardiac clinic. Three
patients were discharged in a stable condition to other hospitals
around South Africa. Three patients did not return for routine
follow-up visits. We cannot exclude sudden cardiac deaths in
patients who were not confirmed to be alive. In contrast, 14 out
of 25 patients were alive in the DCMO control group. As a large
number of TIC patients were lost to follow up, we could not
make a meaningful comparison with DCMO patients regarding
long-term prognosis and outcome.
Limitations
This was a retrospective study with a small number of TIC
patients. The patients represent a select group of non-consecutive
patients referred to a regional referral hospital. It is likely that a
sizeable number of patients with TIC were not included in this
study. The true prevalence of TIC in patients with tachycardia
can only be answered by a prospective study or CMO registry.
Although care was taken to examine all ECGs prior to
presentation to calculate average heart rate, this may not be a
true reflection of average heart rate during a 24-hour period.
An accurate duration of the tachycardia before presentation was
difficult to determine. Patients cannot always recall the exact
duration of palpitations and patients could have a tachycardia for
a variable length of time before an ECG is performed.
Not all patients with pure TIC had coronary angiography
to exclude coronary artery disease, although no coronary
intervention was performed between presentation and when
LV function had recovered to account for improvement in LV
function. Not all patients at presentation had echocardiography
performed in sinus rhythm. The calculation of LV systolic
function in the presence of a shortened diastolic filling time may
result in an underestimate of LVEF.
In this study we were unable to control for the effects
of differences in heart rate or rhythm in the assessment of
LV function at initial presentation and after control of the
tachycardia. Unfortunately, heart rate and rhythm at the time of
the initial LV assessment at echocardiography were not routinely
recorded on the echocardiography or radionucleotide imaging
reports at our institution. However, echocardiographic reports at
slower heart rates were preferentially recorded for LV functional
assessment for better accuracy of LV function. When more
than one echocardiogram was performed in short succession,
an average of the LVEF and LV dimensions were calculated
from serial echocardiograms to improve accuracy. In some
cases, echocardiography was not performed at our institution.
Echocardiography and interpretation of ECGs were often the
interpretation of one cardiologist.
The small control group of 25 DCMO patients was limited
by the number of DCMO patients available in the CMO registry.
Treatment of tachycardia varied between cardiologists and was
not administered uniformly. The long-term prognosis of TIC
