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.