EXTRA COPY — ECG Blog #528 — What's the Rhythm? Why? — EXTRA COPY

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Figure-1: The initial ECG in today's case — obtained from a XXXX (To improve visualization — I've digitized the original ECG using PMcardio).

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Figure-2: I've labeled today's ECG.

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Figure-3: Laddergram of today's rhythm.

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GREAT post on FB from Cardiology Notes (on Facebook !!! )
—  YES — I can acknowledge them as “Cardiology Notes” — and perhaps I should give the link to this post on FB?
— Also to acknowledge — Omar Hassan and Khaled Ash (both from FB !!! )
 
TITLE of MY BLOG POST —
 — “The Patient just left … “
 
THIS IS THE CASE from Cardiology Notes:
https://www.facebook.com/good.job.692776/posts/pfbid0gY4XyPWXBYniYjdLoifq7oPJji2sMU8V7G3d1jAgd5nmUbyuRa8LRZitH7RZqCArl
 
A 54 year old female patient with history of ischemic heart disease complaining of palpitations and dyspnea
MY 1stt REPLY:
FASCINATING rhythm! I've taken the figure posted by Khaled Ash (above) — and have added light BLUE arrows that to me suggest 1:1 retrograde V-A conduction (in addition to the suggestion of 3:2 Wenckebach conduction!
Possibilities are several — in addition to AIVR with 3:2 Wenckebach conduction out of the ventricular focus — this could be junctional with a baseline ECG showing MBBB ( = Masquerading Bundle Branch Block), again with 1:1 VA conduction backward and 3:2 Wenckebach out of the AV node.
My PLEA to Cardiology Notes — PLEASE GIVE US FOLLOW-UP of this fascinating case! Surely YOU have some follow-up!
— What does the baseline ECG look like?
— Is this patient on Digoxin? (if so — likely Dig Toxicity)
— What happened? (Recent acute MI? Electrolyte abnormalities?)

 
MY 2nd REPLY:
NOTE: Cardiology Notes and Omar Hassan, Khaled Ash and myself have all been corresponding about this fascinating case. The patient is on Respiridone (See attached — as this psychotropic medication IS associated with a number of adverse effects that may have contributed to this unusual cardiac arrhythmia !!!
Otherwise — Cardiology Notes has shared with us that this patient signed out of the hospital on his own, refusing further evaluation. Pt was not cooperative !!! — but at least he felt well enough to sign out AMA on his own !!!
I would have loved to see a copy of his previous ECG to help determine if today's rhythm is supraventricular (with MBBB) vs ventricular in etiology as a possible adverse effect from Respiridone ...
 
Respiridone — high risk of sudden death
Ray et al — N Engl J Med 360(3):225-235, 2009
https://pmc.ncbi.nlm.nih.gov/articles/PMC2713724/
 
Users of typical antipsychotics have increased risk of serious ventricular arrhythmias and sudden cardiac death. However, less is known regarding the cardiac safety of the atypical antipsychotic drugs, which have largely replaced the older agents in clinical practice.
 
At present, less is known regarding the cardiac safety of the atypical antipsychotic drugs, which have largely replaced the older agents in clinical practice. Several atypical antipsychotics block repolarizing potassium currents² and prolong ventricular repolarization,^1,13 and the electrophysiologic effects of some drugs are comparable to those of the older agents. However, although torsade de pointes has been reported with atypical antipsychotics,^14–16 whether these drugs increase the risk of sudden cardiac death to the same extent as the older medications is unknown. We thus conducted a large retrospective cohort study designed to compare the risk of sudden cardiac death for the two classes of antipsychotic drugs.
 
Our study did not assess the mechanisms by which either class of antipsychotics increased risk of sudden cardiac death. Although antipsychotics have chronic adverse cardiovascular effects,¹² the risk of sudden death was elevated in an analysis excluding long-term users, which suggests that acute drug effects are involved. We believe the most plausible explanation is that antipsychotic drugs increase the risk of serious ventricular arrhythmias, probably through blockade of potassium channels and prolongation of cardiac repolarization. However, other mechanisms may be involved, including autonomic effects, inhibition of other ion channels, or other acute cardiotoxicities, such as the myocarditis associated with clozapine use.³⁸
In conclusion, current users of both typical and atypical antipsychotics in the study cohort had a similar dose-related increased risk of sudden cardiac death. This suggests that with regard to this adverse effect, the atypical antipsychotics are no safer than the older drugs.
Respiridone does prolong the QTc — but unless there is an overdose, usually by not enough to cause Torsades — it may cause bradycardia — it may cause av block (although this is less common at lower doses.