Part of our study was to review the current criteria particularly Brugada 1991 (8) and John Camm 1994 (21). We found that the overall sensitivity, specificity positive predictive and negative predictive value of each were as follow:
Regarding Brugada algorithm with more meticulous analysis we found that the sensitivity of the 1st step which is absent RS is 42.8% and specificity is 84% and did not reach 100% as previously reported by Brugada et al., 1991.
In 2nd step (RS interval) 100 ms sensitivity (44%) specificity (74%). A finding comparable with data reported by Drew et al., 1995 (22) and the explanation for the increased overall sensitivity & specificity is step 4 where most of the cases were diagnosed by the morphology criteria described by Wellens et al.
Step 3. (The presence of AV dissociation) is highly specific as reported by Wellens et al., and Akhtar et al., yet it was visible on the standard 12 lead ECG in less than one tenth of patients with VT and was demonstrated only by electrophysiologists and not by residents. We agree with John Camm et al., (21) that the typical morphology of BBB was highly specific and sensitive in diagnosing VT by exclusion of SVT with aberration. Finally, despite the fact that both Brugada algorithm and John Camm criteria are very helpful in diagnosis of wide QRs complex tachycardia yet they take much time to interpret, require meticulous measurement and well trained doctors to apply. On the contrary we present new simple approach, easy to interpret with higher specificity 100% and positive predictive value 100%.
Conclusion:
We recommend using this new criteria of predominantly negative QRS complex in at least two out of four leads I, II, V1, V6 (L1 or V6 to be included) in diagnosis of wide complex tachycardia because it was both highly sensitive and specific in segregating VT from aberrantly concluded SVT, our new criteria presented for the 1st time can be used as a simple approximate tool to differentiate wide complex tachycardia in the critical care setting and may help avoid misdiagnosis with its attendant therapeutic risks.
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