Pimobendan as positive chronotrope

RE: Pimobendan as positive chronotrope

Julian Earl — Thu, 13 Aug 2020 16:09:54 GMT

[quote userid="14690" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/29276/pimobendan-as-positive-chronotrope/224878#224878"]I think the benefit seen in Dobes with AF is likely to be due to improvement in myocardial function, not as a direct effect on AF rate. And I’d be wary of diagnosing AF in a Dobe without an ECG - I’ve had several dogs with freq VPCs who sounded like they had AF - not sure Julian if your cases had been ECG’d or not so forgive me if I’m being presumptive.
[/quote]

|Not at all Dave, I thought that my presumed diagnosis of AF was a straightforward one, basedon clinical presentation and the signs? . A dog of a breed with known tendency, irregular tachycardia and my pulse deficits, terribly pale/ashen mucous membranes, zero exercise tolerance ,dyspnoea, or more accurately; polypnoea really.. The MMs, the auscultation and pulse deficit made it an obvious presumption! I understand the doubts due to lack of ECG- results but I think my first case was confirmed by ECG many years ago and others were virtually identical presentations. A number were diagnosed in German Shepherds as well. I cannot recall now any other breeds I have seen seen like this, if any at all...

Also I had considered that the dramatic clinical improvements were likely due to the improved myocardial function and not a chronotropic effect. But because I had experienced very disappointing results with digitalisation, Vetmedin rapidly became my go-to medication for this presentation!

RE: Pimobendan as positive chronotrope

Dave Dickson — Thu, 13 Aug 2020 15:33:58 GMT

I think the benefit seen in Dobes with AF is likely to be due to improvement in myocardial function, not as a direct effect on AF rate. And I’d be wary of diagnosing AF in a Dobe without an ECG - I’ve had several dogs with freq VPCs who sounded like they had AF - not sure Julian if your cases had been ECG’d or not so forgive me if I’m being presumptive.

Dave

RE: Pimobendan as positive chronotrope

Julian Earl — Thu, 13 Aug 2020 14:39:37 GMT

[quote userid="16471" url="~/001/veterinary-clinical/small-animal/cardiology/f/discussions/29276/pimobendan-as-positive-chronotrope/224869#224869"]obes with presumed primary cardiomyopathy and failure with AF?[/quote]

Yes thanks... TAF is very distinct on ausculation and clinical examination, with the pulse deficits etc.

RE: Pimobendan as positive chronotrope

Roger Wilkinson — Thu, 13 Aug 2020 10:59:05 GMT

Dobes with presumed primary cardiomyopathy and failure with AF?

RE: Pimobendan as positive chronotrope

Julian Earl — Thu, 13 Aug 2020 10:55:05 GMT

Am I alone in having found it extremely useful for dogs with Atrial Fibrillation? I have seen Dobermanns with marked AF and complete lack of exercise tolerance show dramatic clinical response to Pimendoban. At university we had been pointed towards digitalis drugs but Pimendoban has been dramatically better. Any comments please?

RE: Pimobendan as positive chronotrope

Dave Dickson — Wed, 12 Aug 2020 21:36:40 GMT

That’s a typo. Should be 0.1-0.3mg/kg BID.

I use standard doses (0.25-0.3mg/kg BID) with similar experiences to Chris.

Dave

RE: Pimobendan as positive chronotrope

Roger Wilkinson — Wed, 12 Aug 2020 21:23:40 GMT

just been brought to my attention that Mike Martin in his ECG book suggests pimo at 1-3mg/Kg bid in heart block.

what doses are you using Chris?

RE: Pimobendan as positive chronotrope

Roger Wilkinson — Wed, 12 Aug 2020 20:54:59 GMT

good stuff! that's exactly the info I wanted... just started an occasionally syncopal bradycardic 2AVB 15 y.o. on pimobendan since pacemaker a bit beyond what was really practical...fingers crossed

RE: Pimobendan as positive chronotrope

Chris Linney — Tue, 11 Aug 2020 09:55:33 GMT

The treatment of choice for symptomatic bradycardia is often pacemaker implantation but it’s not always feasible.

We frequently have clients who travel a few hundred miles for pacemaker implantation or need time to decide if they wish to pursue surgery. In addition there are patients where surgery is not an option.

Based on retrospective data, for the third degree AV blocks and the sick sinus syndrome cases where there has been a delay in pacemaker implantation, we have seen that pimobendan can act as a reasonable bridge to pacemaker implantation. Dogs frequently have resolution of clinical signs or a reduction in syncopal episodes.

There a small number of patients that get an initial benefit from starting pimobendan but clinical signs recur or they have no response to therapy at all; most of these patients went on to benefit from immediate pacemaker implantation.

As Roger mentions, there is some evidence that pimobendan may have chronotropic benefits, but improvement in cardiac output may also explain why pimobendan can benefit these patients. There is a case report which shows a positive association between PDE3 inhibitor cilostazol and SSS in a dog and we will shortly be reporting our case series of dogs.

Case Report:

“Kanno, N. & Suzuki, T. (2017) Long term effects of cilostazol in a dog with sick sinus syndrome. J Vet Med Sci; 79(6): 1031–1034.” doi: 10.1292/jvms.17-0018

The paper Roger refers to is:

Furukawa, Y., Akahane, K., Ogiwara, Y., Haniuda, M. & Chiba, S. (1989) Positive chronotropic and inotropic effects of pimobendan (UD-CG 115 BS) in isolated, cross-circulated canine heart preparations. Arch Int Pharmacodyn Ther; 300: 159-73

Traditionally vagolytics or sympathomimetics like propantheline and terbutaline have also been used for the management of sick sinus syndrome and these drugs still have their place. It is likely that pimobendan should also sit on the same shelf for medical management of bradyarrhythmias, and this is our experience. For SSS I will typically try these first but have a number of patients that have shown a much better response to starting or adding pimobendan.

I haven’t personally used propentofylline but as xanthine derivative it is a reasonable option too.

My recommendation, based on our retrospective data is that pimobendan should be considered as bridging treatment for complete or high grade second degree AV block where pacemaker implantation cannot proceed immediately or is not a viable option.

RE: Pimobendan as positive chronotrope

Beats — Fri, 07 Aug 2020 11:20:42 GMT

i have been pleasantly surprised on more than one (OK, just two I think) occasion in giving a dog propentofylline (expecting no effect) in little dogs that were symptomatic with bradycardia from large pauses between beats.

These are similar sorts of drugs, are they?