Results:
Data of 65 patients who underwent CSD during the above mentioned period
for refractory VT / VT storm and had at least six months of clinical
follow-up was available for analysis and interpretation. There were 50
(77%) males and 15 (23%) females,age 50 ± 18 (range 1-81) years in the
cohort. The duration of follow-up was 27±24 months[median 20 (IQR
12-36)months]. The baseline characteristics are shown in Table 1. The
left ventricular ejection fraction (LVEF) was 0.28 ± 0.13 prior to CSD.
25 (38.5%)patients had severe (LVEF 0.20-0.35 ) LV dysfunction and 29
(44.6%)patients had very severe (LVEF <0.2) LV
dysfunctionprior to CSD.
Three (4.6%) patients were in NYHA class I, 20 (30.8%) in class II, 35
(53.8%) in class III and 7 (10.8%) in class IV. The underlying
substrate was for VT was coronary artery disease in 30 (46.2%) patients
and 35 (53.8%) patients had a variety of other non-ischemic causes,
prominent ones being dilated cardiomyopathy and old myocarditis(Table
2).Nineteen (29.2%) patients had sustained monomorphic (single
morphology) VTs, 38 (58.5%) patient had pleomorphic (≥2 VT
morphologies) and 8 (12.3%) had polymorphic VTs. An ICD or a CRT-D had
been implanted in the past in 57 (87.7%) patients. After CSD, no
further ICDs were implanted.Eight patients in the initial study period
underwent TEA before subjecting them to CSD. This led to control of
arrhythmia in 6 patients while 2 patients showed no response to TEA.
However, after our initial experience of encouraging results of CSD, we
changed our strategy and directly considered CSD without waiting to see
the response to TEA.
Only 14(21.5%) patients had previous attempt of catheter ablation of VT
while the other 51 (78.5%) patients were considered for CSD without a
prior catheter based ablation. Seventeen (25.8%) of patients were on
single, 37 (56.1%) on two and 11 (16.7%) on three antiarrhythmic drugs
(AADs)prior to CSD. The most frequently used AAD was amiodarone in
55(83.3%) followed bybeta-blockers in 41 (62.1%) of patients(Table
3).60 (92.3%) of our patients underwent bilateral CSD and only 5
(7.7%) underwent unilateral left sided CSD.
Success of CSD: By the definition described earlier in
the methods section, 47 (72.3%) patients fulfilled criteria of complete
responder, 4(6.1%) were partial responders and 14 (21.5%) were
non-responders. Amongst patients with complete and partial response,
(6.1%) were delayed responders as they continued to have appropriate
shock till 3 months after CSD but not thereafter. For analysiswe
combined the complete and partial responders and compared them with
non-responders. The comparison has been shown in Table 1. The only
significant difference was that non-responders were predominantly in
NYHA III and IV.