The Take Home: HRS
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In May, the Heart Rhythm Society Annual Scientific Sessions were held virtually for the first time. Attendees were able to access sessions via the HRS Learning Portal at heartrhythm365.org.
Healio and Cardiology Today covered the meeting remotely and reached out to a number of experts on arrhythmia disorders for their perspectives on key presentations, including Cardiology Today Next Gen Innovator Daniel J. Cantillon, MD, FACC, FHRS, from Cleveland Clinic; Jodie L. Hurwitz, MD, FHRS, from Medical City Hospital, Dallas; Andrew D. Krahn, MD, FHRS, from the University of British Columbia; Fred M. Kusumoto, MD, FHRS, from Mayo Clinic, Jacksonville, Florida; and Oussama Wazni, MD, MBA, from Cleveland Clinic.
Editor’s Note: All coverage from Heart Rhythm Society Annual Scientific Sessions can be found here .
BLUESYNC
Hurwitz: The take-home message from the BLUESYNC study is that using technology that we all carry with us everywhere can improve patient follow-up, which can improve patient care. This could lead to less need for in-office visits. All of this can ultimately increase patient satisfaction.
Researchers analyzed data from patients from April to December 2018 who had a device, pacemaker or cardiac resynchronization therapy pacemaker that was compatible with Bluetooth-enabled remote monitoring technology (BlueSync, Medtronic). The analysis included 245 patients who had the BlueSync technology, 979 patients who had pacemakers that required a wand to manually communicate information with a bedside console, 980 patients with pacemakers with wireless automatic communication through a bedside console and passive transmission and patients with defibrillators with similar automatic communication.
Transmission success was 94.6% for BlueSync (95% CI, 91.8-96.6), 56.3% for those with pacemakers with wand transmission (95% CI, 53.7-58.9), 77% for patients with pacemakers with wireless automatic communication through a bedside console and passive transmission (95% CI, 74.4-79.4) and 87.1% for those with defibrillators with automatic transmission (95% CI, 85.2-88.8). The BlueSync transmission success rate in this cohort was similar to that of a cohort of real-world patients using the technology.
As clinicians, our goals are to improve our patients’ lives, and better follow-up ensures this. Patients will also be reassured that we have received their data download; previously, there was not an automated way of doing this.
It would be interesting to know whether there are subsets of patients in whom this is not as useful, ie, older patients, although it appears the older patients did better than the younger ones.
This is the way of the future. This can decrease office visits while reassuring patients that their information/data was received.
SWISS-AF
Wazni : In the SWISS-AF cohort of 1,227 well-treated patients with atrial fibrillation, most of whom were on oral anticoagulation, more than 5% had a new brain infarct detected by MRI at 2 years.
The main takeaway is something we tell our patients: While the risk for stroke while taking oral anticoagulation is significantly decreased, major nonsilent stroke may still occur depending on the risk profile of the patient. Therefore, I am not surprised they may also have silent infarcts. The reason these patients are on an anticoagulant is because they are at high risk for stroke due to other comorbidities such as hypertension, diabetes, coronary disease and vascular disease. Those risk factors alone can cause silent infarcts.
What the study did not tell us clearly is whether these infarcts are embolic or nonembolic. The anticoagulants are for protection against embolic strokes. These silent infarcts can be a manifestation of preexisting conditions such as hypertension, diabetes, hyperlipidemia and preexisting cerebrovascular disease.
However, we do not want patients with AF thinking that anticoagulants are not useful.
The main impact of the study is that we have to mitigate those other risk factors to decrease the risk of silent stroke and subsequent cognitive decline. The median CHA2DS2-VASc score was 3, so these patients had a high number of very significant risk factors that need to be addressed. The mean BP in this group was 135/79 mm Hg. We can do better than that. The cholesterol profile was not provided, but that has to be managed as well. Same with diabetes, which was also not described. Just saying that taking a blood thinner is good enough is not enough. We have to encourage doctors and patients to manage the entire risk profile.
We need to better characterize these infarcts and better understand their etiology. Further studies should have more patients; larger cohorts that can be included exist. We also need to look at the impact of strict risk factor modification to see if it has any benefit. This study is important because it provided a baseline risk, and now we know what to expect with patients on anticoagulants. Future studies can assess if we can further decrease the incidence shown in this study by adherence to strict risk factor modification.
Long QT syndrome risk calculator
Cantillon: In an elegant study, investigators from the University of Rochester and Italy developed and validated a 5-year risk score calculator tool for lethal arrhythmias among patients with long QT syndrome. The investigators appear to have been inspired by a similar 5-year risk score calculator for patients with hypertrophic cardiomyopathy.
Between 6% and 9% of patients with congenital long QT syndrome will have life-threatening events between age 18 and 40 years. To identify which patients are at greatest risk for such events, the researchers developed and validated a model including prespecified time-dependent covariates of baseline-corrected QT, age, sex, syncope —never, syncope while off beta-blockers or syncope while on beta-blockers — beta-blocker use and genotype.
The score is easy to use and can help physicians counsel patients with long QT syndrome on their risk for sudden cardiac arrest given the reasonably good C-statistics from the internal and external validation cohorts.
It is unclear if the score can guide medical decision-making, including patient selection for ICDs, as the inspired model for hypertrophic cardiomyopathy does — providing the user both an estimated 5-year risk percentage and professional society recommendation on ICD. Further research would be required for this score to get to that point.
One inherent challenge for these predictive models is keeping up with the science in dynamic fields while preserving the convenience of an easy-to-use tool. For example, the current European Society of Cardiology hypertrophic cardiomyopathy 5-year calculator does not use the patient’s scar burden by cardiac MRI as an input variable, which has been shown to be a very important determinant of risk in this patient population and remains part of the American Heart Association algorithm to guide ICD medical decision-making. While there is no immediate obvious example to parallel this among patients with long QT syndrome, most experts would agree they are similarly nuanced by science surrounding triggering events, exposure to QT-prolonging-drug therapies, circadian rhythm, etc.
Leadless vs. transvenous pacemakers
Hurwitz: Leadless pacing in appropriate patient populations is available and here to stay.
A study comparing a leadless pacemaker (Micra, Medtronic) to transvenous VVI pacemakers showed in a large real-world population of more than 15,000 patients that leadless pacemakers have the ability to eliminate the risks seen with device leads.
At 30 days, there were no significant differences in overall acute complications in the Micra and transvenous VVI pacemaker groups (7.7% vs. 7.4%, respectively). Patients implanted with the Micra had lower rates of device-related complications (1.4% vs. 2.5%; P < .05) and higher rates of cardiac effusions/perforations (0.8% vs. 0.4%; P < .05) and events at the puncture site (1.2% vs. 0.3%; P < .05) compared with those treated with transvenous VVI pacemakers. At 6 months, overall complications (3.3% vs. 9.4%) and device-related complications (1.7% vs. 3.4%) were lower in the Micra group vs. the transvenous VVI pacemaker group.
There is a patient population where leadless pacemakers should be considered rather than transvenous pacemakers. The worry that these leadless pacemakers are not as effective or have more complications is not supported when real-world data are evaluated.
It would be interesting to see results of a randomized trial of leadless vs. transvenous single-chamber ventricular pacing. It will also be interesting to see studies looking to minimize access problems and evaluate learning curves.
Leadless pacing is the way of the future. Leads are a major problem with available transvenous devices. Keep your eye out for devices that sense in both the atrium and ventricle.
Atrial fibrosis in ESUS
Kusumoto : Using MRI to quantify atrial fibrosis in 201 participants, researchers found that patients with embolic stroke of undetermined source (ESUS) had higher atrial fibrosis levels (14.7%), similar to patients with established AF (16.6% to 17.9%) and significantly higher than controls with no AF or prior stroke (8.1%). After an estimated median follow-up of 12 months, eight patients suffered a recurrent stroke, developed AF, or both simultaneously, and these patients were more likely to have higher levels of atrial fibrosis at initial evaluation.
An important message of this study is that patients with ESUS have a high risk (16%) for recurrent stroke or developing AF within the next year and require careful evaluation and follow-up. While this is a preliminary study, it provides evidence that measuring atrial fibrosis in patients with ESUS could be used to identify those patients who are at highest risk.
Looking to the future, it may be that quantifying atrial fibrosis could potentially help guide therapy to improve outcomes. For example, would larger prospective studies find that patients who have not had AF but have high levels of atrial fibrosis benefit from anticoagulation or other interventions targeting AF or its sequelae?
Finally, since atrial fibrosis seems to be an important predictor for the development of AF, as also suggested by PREDICT-AF, this study provides more stimulus for exploring whether one of the many molecules involved in the complex systems that mediate the development of atrial fibrosis could be a potential target for the treatment of AF or perhaps even prevent the development of AF.
PRAETORIAN
Krahn: The technology of subcutaneous implantable cardioverter defibrillators is about 10 years old and has much less of a robust track record than the transvenous ICD does. As a result, there is enthusiasm about the concept of changing the nature of the technology that can serve a certain patient population. The real question was how broadly useful it is and how it compares to the older technology. As a result, there are varying degrees of adoption based on enthusiasm about the technology, but not a lot of evidence other than case series, and no good comparative evidence in a randomized trial.
The community has been looking forward to a comparative study such as PRAETORIAN, which was designed as a noninferiority trial. The main reason for that was because the assertion was not that the device was necessarily superior; they both have strengths and weaknesses. We have been discussing this with patients since the introduction of the technology.
Researchers randomly assigned 849 patients with indication for an ICD to receive a subcutaneous ICD (Emblem S-ICD, Boston Scientific) or a transvenous ICD. The primary composite endpoint of ICD-related complications and inappropriate shocks at a median of 48 months occurred in 15.7% of patients in the transvenous ICD group and 15.1% in the subcutaneous ICD group. The individual components of the primary endpoint also did not differ between the groups.
The key takeaway point is that the device was as effective and safe as a transvenous ICD. The limiting factor with the subcutaneous ICD is the absence of antitachycardia pacing. In the early data, there was concern about incidence of inappropriate shocks. The key thing that happened with PRAETORIAN was that the investigators were systematic about both the programing of the patients for shocks as well as the nature of the arrhythmias.
The corollary of this is we have known for years that a transvenous lead system has its limitations from the standpoint of a surgical implant, the complications around lead performance, etc. If anything, the surgical complications and short-term complication rates were comparable or a little higher with the transvenous system. This suggests that if there is an expert implant team on both sides of the technology, the use of either technology is supported. Arguably, in the right hands, the subcutaneous ICD may end up being a more durable technology.
What we still want to see in an extension study is what happens over time because we know, for example, transvenous leads have durability issues as their Achilles’ heel.
The degree of uptake in the global community has been modest because it has been more targeted at patients who are intuitively going to benefit. The real question in this situation is now that the device has shown equivalence, will the uptake in a more general ICD population be greater? That also speaks to the UNTOUCHED trial, and it argues that you can go into a conversation with a patient about the surgical procedure and be open-minded to either technology based on the details of clinical judgment and patient preference.
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