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In This Week’s Podcast
For the week ending February 21, 2025, John Mandrola, MD, comments on the following topics: Blanking period after AF ablation, periprocedural MI after PCI in non-STEMI, predicting AF after ischemic stroke, and the proper standards for mitral valve repair in primary mitral regurgitation (MR).
Blanking period after AF ablation
As many of you know, EP doctors have blessed themselves with something called a blanking period after AF ablation. That is, AF that occurs in the 12 weeks or 8 weeks or sometime after the procedure period does not count against procedural success.
It’s one of these dogmas that got established and has never been questioned. The idea being that thermal energy from the ablation can actually cause irritability of the atrium and then it might cause AF that then settles down. That’s the idea.
Before I tell you about my friend Jason Andrade’s study in Circ A&E, I will remind you about the blanking period after percutaneous coronary intervention (PCI), or the blanking period transcatheter aortic valve Implantation (TAVI), or after left atrial appendage closure (LAAC). Wait. You ask, what blanking period? And you would be correct. There are no blanking periods after these other procedures. In fact, I know of no other cardiac procedure which is gifted a period of time after the procedure where failures don’t count.
The research letter from Dr. Andrade’s group centered on how AF ablation blanking period impacts AF recurrence and AF burden. Andrade and colleagues used data from the 2019 CIRCA-DOSE trial, which was a three-armed RCT comparing RF, 4 min cryoballoon freeze (CB) vs 2 min CB. All patients in that trial had implantable loop recorders (ILRs). The main trial showed all three modalities provided similarly poor efficacy of the primary endpoint of time to first AF. It was about 53% in all 3 groups. And I say poor because, remember, AF ablation results are poor, and have not improved in 20 years.
Recently, the European guidelines recommending shortening the blanking period from 12 weeks to 8 weeks. Having ILR data on these 346 patients in Circa-Dose trial allowed the authors to describe differences in outcomes based on timing of recurrence after the procedure.
They had four main findings with the 8-week rather than 12- week blanking period:
One-year freedom from any tachyarrhythmia was significantly lower with 8 weeks; it was 50%, vs 55% with 12 weeks. That 5% drop in efficacy was statistically significant. The absolute number of patients who recurred early was only 14 of 346, or 4%.
The good news though was that AF burden (which can be measured with an ILR) was not statistically significant; it was very low in both groups (0.18% vs 0.23% in 8 weeks and 12 weeks, respectively.)
Progressively shortening the blanking period from 6 weeks to 4 weeks to 2 weeks were associated with progressively lower binary freedom from AF but did not appreciably change the AF burden.
The most interesting finding of their paper was that patients who recurred early vs only late had nearly 20x higher burden than those that failed later.
This latter finding caused the authors to conclude that shortening the blanking period would enable earlier intervention (re-ablation) but at the expense of potentially overtreating a minority of patients (about 4%) who recur but have a very low burden going forward.
The Basel, Bern, and Baltimore EP group also published a subanalysis of a trial looking at the impact of the 8-week blanking period. Published in Heart Rhythm 2 months ago, in December. Their trial was a head-to-head comparison of the Boston Sci CB vs MDT CB. All patients had loop recorders.
They did a similar thing to Andrade et al. They took the more than 5200 episodes of early recurrence of atrial tachyarrhythmia (ERAT) and studied the relationship of timing and late failures.
First—early episodes of AT were common. 58% of patients occurring in 58% of patients. Pause there. We have a humbling job.
Second – it mattered. If there was an ERAT than there was a much higher failure rate. Success occurred in 82% vs 37% in patients without vs with ERAT.
Third it was better to have ERAT earlier. When the AT occurred in the first, second or third months of the blanking period the freedom from late recurrence was 60%, 56%, and 11%. Pause there again. Recurrence in the third month translates to 89% chance of failure.
Fourth finding was relatively good news: only 7 of 200 patients 3.4% had AF recurrence in the third month so the new 8 week blanking period would reclassify only a small number of success to failure.
Another Paper on Blanking Period After PFA ablation
Mohanty et al in Heart Rhythm published on a consecutive series of 337 patients who had pulsed-field ablation (PFA) for AF. Fifty-three patients or 16% had ERAT — 10 in the first month, 12 in the second month, and 31 in the third month.
This group noted a huge difference in the risk of late recurrence or failure.
Of the 10 patients with very early (1 month) recurrence, 70% remained in sinus rhythm (SR) with no late recurrences.
But at one year, all patients with recurrences in the second and third month had late recurrences most of whom underwent repeat procedures.
They conclude that the blanking period (BP) with PFA could be reduced to one month, because recurrences in month 2 or3 were so predictive of true failure.
One more unpublished data point
My friend Stefano Bordignon, an EP in Frankfort, Germany, who may have done the most PFA ablation in the world, sent me an email about data he presented at least year EHRA from the Europia registry. It showed similar findings — namely that early recurrences were highly predictive of late recurrences. He and Vivek Reddy communicated that all the data with PFA is from symptomatic recurrences, not with ILR data. So that is a limitation.
Stefano made a point that is worth sharing: In my opinion we should really question the blanking period after PFA ablation.
I think that after PFA, a recurrence is a recurrence, even if it happens during the BP.
Because: the rate of durable pulmonary vein isolation (PVI) is in experienced hands so high that a recurrence even during the BP should be considered a sign that the patient is a PVI non responder. Some of these patients would therefore profit from a redo ablation even during the BP.
But the big problem is that PFA is so fast and with a favorable safety profile that in Europe we started to ablate patients that we would have never ablated few years ago.
Therefore… so some recurrences in the BP are not a technology failure but a failure in the indication process and patient selection.
Final Comments
I think I can make this who thing simpler. Mohammed Ruzieh, Andrew Foy and I wrote a brief editorial in AHJ Open with the title “Patients’ Lives Don’t Pause for Blanking Periods.”
We argue that there should be no blanking period. Foy told me this week when he admits patients for AF early after ablation, the patient who gets admitted, put in a hospital bed, with an IV, and then has to have cardioversion or more drugs does not feel like the episode doesn’t count.
Of course it counts. I would add that some of these early recurrences are for left atrial flutter which are worse than AF because the slower atrial rate often means faster ventricular rates. Though, thankfully, we see less pure atrial flutter of late because we stopped carpet bombing so much on the first procedure.
Our other argument for vanquishing the blanking period is it complicates trial interpretation. As I’ve shown you, counting the early recurrences reduces the success rate to what is closer to truth. And now with PFA, it looks more and more like there should be no blanking period.
But our strongest argument for starting the success or failure count from the procedure is that no other procedure in cardiology does it. Consider, the issue of counting Mis in the ISCHEMIA trial of invasive vs conservative strategy in patients with ischemia and CAD. In the main analysis there was no difference in the composite major adverse cardiovascular events (MACE) nor in myocardial infarction (MI). However, if ISCHEMIA had a blanking period wherein post-PCI MI were not counted then the trial would have shown statistically significant 33% reduction in MI the invasive arm vs conservative. Page 92 in the supplement.
But it is not fair to exclude time around the procedure. I was hugely critical of the OPTION trial of LAAC plus AF ablation vs direct oral anticoagulants (DOAC) after ablation because the authors’ choice of primary safety event excluded bleeding during or right after the procedure.
I would argue that in the same way that these two examples are wrong, so has it been wrong to even have a blanking period at all. The European Society of Cardiology (ESC) has decreased it to 8 weeks, but I would like to persuade you all to reduce it to 0. Then the playing field is level for everyone. And perhaps we don’t look so foolish to our non-EP colleagues.
Speaking of Periprocedural Events…
Circulation published a nice study from an Italian group, first author Matteo Armillotta, looking at future events after periprocedural myocardial injury (PMI) with or without Type 4a MI after a PCI which was done for non-ST-elevation myocardial infarction (Non-STEMI).
I liked the study for many reasons, but mainly, it clearly illustrates why it is important to consider events around the time of an invasive procedure. Here PCI for patients with Non-STEMI.
These were consecutive patients from an observational registry done in Bologna Italy.
Two definitions — to have periprocedural myocardial injury, or PMI required a 20% increase in Trop and absolute postprocedural value of ≥5 times the 99th percentile upper reference limit (URL).
Type 4a MI was diagnosed in the presence of injury if there were a) new ischemic ECG changes, (b) development of new pathological Q waves, (c) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic origin, or (d) angiographic findings consistent with a procedural flow-limiting complication such as coronary dissection, loss of a side branch, slow flow, thrombus, or distal embolization.
The primary endpoint was all-cause death. Secondary endpoints were composite MACE-type things. There were about 1400 patients included.
The main findings:
A substantial proportion of non-STEMI patients in this series (37%) met the criteria for periprocedural injury. About 17% also had criteria for type 4a MI. These were about 70-73 year-old patients. One-third female.
Periprocedural myocardial injury (PMI) increased the risk of death at one year as well as MACE. The aHR for future death was 2.7 (1.8-4.0) PMI vs no PMI.
If there was PMI with 4a MI vs PMI vs no 4aMI then the aHR was 2.94 (1.7-5.0) for death.
For MACE the trends were similar, though aHR were less robust (1.4) for PMI vs no PMI and 2.2 for 4aMI vs no-4aMI.
A post-PCI ΔcTnI >20% but ≤40% was associated with 1-year outcomes similar to those observed in patients with post-PCI ΔcTnI ≤20%. Conversely, a post-PCI ΔcTnI increase of >40%, combined with an absolute postprocedural value of ≥5 times the 99th percentile URL, was identified as the best threshold for diagnosing a prognostically relevant PMI.
Patients exceeding this threshold had a significant 4-fold and 3-fold increased risk of 1-year all-cause mortality and MACEs, respectively.
Some contextual things discussed in the paper:
The threshold they estimated of more than 40% increase in troponin is higher than that noted in PCI of chronic syndromes. Of course the authors say these previous thresholds are grounded in expert opinion. But this data suggests that they may be overly sensitive, and it may take more of a rise of troponin to have prognostic utility.
That said, they write, and I agree, that none of this speaks to any therapeutic changes. Because of course we would maximize secondary prevention therapies whether the troponin rises 20%, 40% or 50%.
My point in showing you this data is that events around the procedure—even a surrogate marker such as troponin—should be counted in outcomes. There is no blanking period after PCI; because these events are prognostic, as are ERAT after ablation.
This is a nice paper and it is worth a look.
AI to detect AF-related stroke
eClinicalMedicine journal, which is part of the Lancet journals, published an interesting study applying artificial intelligence (AI) to brain MRI scans in patients with stroke to detect AF.
I was drawn to the study because it is so darn clinically relevant. Embolic ischemic stroke without obvious evidence of AF always brings up the question of which anti-thrombotic to use. We know that there are two negative trials of DOACS for embolic stroke of undetermined source (ESUS), but we also know AF is a likely cause. The answer now is to monitor for AF—this is costly and takes time.
The team from China developed a convolutional neural network to sort out patterns from brain MRI to ID AF. I am no expert in AI or machine learning. So it’s hard for me to comment on the details, so I asked around. But the idea of this study is super-important. It is about prediction. Something we doctors struggle with.
AI models generally follow these steps:
First, there were 510 stroke patients retrospectively enrolled to develop the algorithm. Then 73 patients were prospectively enrolled to test the algorithm.
Then, an external cohort from two other hospitals were retrospectively used for further model validation. The endpoints were are under the curve (AUC), sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV).
A combined classifier leveraging pre-defined radiomics features and de novo features extracted by convolutional neural network (CNN) was proposed to identify underlying AF in acute ischemic stroke patients
Before I tell you the results, notice the very small number of patients. Two experts I reached out to said training models with neural networks usually takes many more patients.
In the three groups, the internal retrospective, external retrospective and prospective test, AF occurred in about a third of patients.
In the end, the combined radiomics features and CNN had an AUC of 0.87, sensitivity 87%, Specificity, 79%, PPV 68% and NPV 94% for predicting AF.
The authors concluded that there was a potential association between brain ischemic lesion pattern on MR images and underlying AF. Furthermore, with additional validation, the AI model we developed may serve as a rapid screening tool for AF in clinical practice of stroke units.
Comments:
Again, I feel like we are at a point similar to practicing medicine without internet or smartphones. AI feels transformative.
Let me also say there are some post-stroke cases which are highly suggestive with use of normal intelligence. Such as multiple cortical stroke areas, large LA, history of AF, and no atherosclerosis. You don’t need AI to suspect AF as causal. You monitor these patients aggressively., But many more cases produce gray areas. And that is where you hope AI could help.
But I don’t think these numbers are good enough for decisions. Sense-wise, 87% sounds good, but the model misses 13% of AF. Specificity of 80% means 1 in 5 is a false positive. Not good.
Another weakness, AF monitoring was only for 3 days. That is not enough. The validation cohort was only 73 patients.
We have to see how these work out with larger cohorts of patients.
I cover this paper not because it is actionable, but I feel like we are on the cusp of something really big.
Mitral Valve Repair
I don’t know about your zip code but in mine, transcatheter edge-to-edge repair (T-TEER) is hot. I like to think of the Field of Dreams saying: Build it and they will come. Well, the mitraclip device has been built, and it’s getting use.
The thing is that we mustn’t forget that surgical repair is the standard — at least for degenerative disease.
JACC has a descriptive paper from the team at San Raffaele center in Milan – home of Dr Alfieri of the Alfieri stitch.
They report on 3300 patients who had surgical mitral valve (MV) repair for degenerative MR between 2008 and 2017.
Median age 57 years. Two-thirds men. The most used technique was posterior leaflet resection followed by edge-to-edge repair. In patients in whom more than one repair techniques was used the second most common procedure was the central Alfieri stitch. Almost all patients (98%) received a concomitant mitral annuloplasty –which cannot be done with T-TEER.
About a quarter had tricuspid repair.
Overall in hospital mortality was 0.5% for all cases. And 0.2% for isolated repair. That’s 5 of 2400 patients.
Ten-year survival was 89%.
And the big one: freedom from reoperation was 97% at 10 years.
10-year freedom from rehospitalization for heart failure was 92.24% (95% CI: 90.62%-93.86%), with age, prior hospitalization for heart failure, preoperative symptoms, and anterior leaflet disease identified as independent risk factors.
Comments:
This paper exposes an uncomfortable truth — one that has been present since I started cardiology. MV repair requires surgical centers of excellence, including surgeons of excellence. To have surgeons of excellence requires them to have excellent training and lots of practice. That could be increasingly challenging in the coming era of non-surgical interventions on valves.
I say an uncomfortable truth because policy people like to think of doctors as interchangeable. And for some things (increasingly AF ablation for instance) that is true, but not for valvular heart surgery. Surely not.
The results from this work are extraordinary. It’s the kind of heart center you’d like to work in or close to.
You might say it’s their own data and, I would say, ok, that is a limitation, but the authors used an independent organization to match up patient outcomes and do impartial assessment of outcomes.
Right now there are three ongoing trials comparing T-TEER to surgical MV repair. T-TEER is going to have to pass a high bar.
I know it’s tempting for patients to choose non-surgical repair because recovery is easy, but at the age of these patients — 57 years — not having another re-op over 10 years is a pretty important metric.
Before we cardiologists go crazy with MV procedures, we ought to know the results of our surgical colleagues. Patients should know that at centers like the one in Milan they will have a less than 3 in 1000 chance of dying from the procedure and a 98% of not having another intervention over the next decade.
We shall see what the trials show, but centers like San Raffaele in Milan are going to be hard to beat.
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