Procedural success comparable in CRT implants and upgrades

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Rates of procedural success and complications were no different between de novo cardiac resynchronisation therapy (CRT) implantations and upgrades, a study published in JACC: Clinical Electrophysiology has concluded. The study compared rates of procedural success and complications between de novo implantation versus upgrade, including the characterisation of technical challenges.

Study author David Nemer (Cleveland Clinic, Cleveland, USA) and colleagues note that CRT is an effective treatment for patients with systolic congestive heart failure and electrical dysynchrony to reduce hospitalisations and mortality, but note that large randomised controlled trials on the benefit of this therapy have concentrated on patients receiving de novo devices. Recent observational studies, they add, have demonstrated that up to 20–30% of all CRT implantations are an upgrade from an existing permanent pacemaker (PPM) or implantable cardioverter-defibrillator (ICD).

“One potential concern with CRT upgrade procedures is that the presence of pre-existing transvenous leads, a pulse generator (PG) with pocket fibrosis, and possible venous occlusive disease (VOD) may increase susceptibility to procedural complications or unsuccessful left ventricular (LV) lead delivery,” they write. “In particular, VOD may result in access problems that require advanced techniques or lead extraction for device upgrade.”

The study reviewed a large cohort of patients who underwent transvenous CRT procedures at the Cleveland Clinic between January 2013 and December 2018 to better define the relative rates of procedural success and complications between de novo CRT implantations and upgrades.

Procedural success was defined as transvenous implantation of the intended device type as determined by the pre-procedural objective, including successful delivery of an LV lead via the coronary sinus (CS). For patients who underwent epicardial lead placement after a previous attempt at transvenous insertion, the initial transvenous procedure was considered unsuccessful.

The study team identified a total of 1,496 patients underwent an initial transvenous CRT procedure, of whom 947 (63%) were de novo CRT implantations and 549 (37%) were device upgrades. An abdominal PG was used in three (0.3%) patients who underwent de novo implantation; all other de novo and all upgrade procedures were performed using a pectoral PG. Of the upgrade procedures, 110 (20%) were a change from a single ventricular lead device to CRT and 439 (80%) were a change from a dual-chamber device to CRT. Lead extraction was performed for venous access in 26 (4.7%) of the upgrade procedures.

The study team reports that there was no significant difference in procedural success rates for LV lead delivery between de novo implantations (n=922; 97%) and upgrades (n=529; 96%) (95% CI for difference: −0.9‒2.9%; p=0.28). The most common reasons for unsuccessful implantation, they report, were the lack of a suitable vein target, inability to cannulate the CS, venous dissection, and LV lead instability, with no significant difference in distribution between de novo implantations and upgrades (p=0.21). Among the three de novo implantations that used an abdominal PG, two were successful.

When analysed by implanted device type, there was no significant difference in the rate of unsuccessful LV lead delivery between de novo CRT pacemakers (CRT-Ps) and CRT defibrillators (CRT-Ds) (2.6% vs. 2.7%; 95% CI for difference: −2.4‒2.6%; p=1), whereas upgrade from a PPM to CRT-P had a lower failure rate than upgrade from a PPM or ICD to CRT-D (0% vs. 4.7%; 95% CI for difference: 2.7% to 6.8%; p = 0.01). Looking at the existing device type, the researchers found that there was no significant difference in the rate of unsuccessful procedures between upgrades of single ventricular lead and dual-chamber devices to CRT (3.6% vs. 3.6%; 95% CI for difference: −3.9‒3.9%; p=1).

In terms of procedural complications, they report that there were a total of 74 procedural complications in 73 patients (4.9%) during the 90-day follow-up period with no significant difference in the overall incidence of any complication between de novo implantations (n = 48; 5.1%) and upgrades (n=25; 4.6%) (95% CI for difference: −1.7‒2.7%; p=0.70). The most common complications in both groups were non-LV lead dislodgement or malfunction (n=21; 1.4%) and upper extremity DVT (n=19; 1.3%), which accounted for 54% of all complications. In the three patients who received an abdominal PG, none had a lower extremity DVT. Upper extremity DVT occurred in four patients (0.6%) who were taking oral anticoagulation, all of whom were taking a direct-acting oral anticoagulant and had a DVT within five days of CRT implantation, and in 15 (1.7%) patients who were not taking oral anticoagulation (95% CI for difference: 0‒2.2%; p=0.07), with a median time to DVT diagnosis of 13 days (IQR: 6.5‒17 days).

Turning to VOD, the study team reports that venography was performed in 439 (80%) of patients who received a CRT upgrade and occurred in advance of the procedure (n=159; 29%), during the procedure before pocket opening (n=259, 47%), or after pocket opening (n=21; 4%). They add that VOD that required a modified procedural technique was present in 125 (23%) patients who received a CRT upgrade, all but six (5%) of whom had a venogram performed. VOD was more common among patients with an existing dual-chamber device compared with a single ventricular lead (n=115; 26.2% vs. n=10; 9.1%; 95% CI for difference: 10.3‒23.9%; p<0.001), but there was no significant difference in the time from initial device implantation to upgrade in patients with VOD compared with those without VOD (6.3 years; IQR: 3.4‒9.7 years vs. 5.5 years; IQR 2.3‒9 years; p=0.13).

Discussing the findings, Nemer and colleagues write that the study found no significant difference in the rate of procedural success between de novo and upgrade CRT procedures or 90-day complications. They note: “Upgrades accounted for 37% of CRT procedures, with VOD requiring a modified implantation technique in 23% of these cases. Importantly, VOD was more common among patients with an existing dual-chamber device (26%) compared with those with a single ventricular lead (9%); management strategies varied according to the pattern of venous obstruction. Overall, patients with VOD who received a CRT upgrade had a similar composite rate of procedural failure or complication as compared to patients without VOD (8% vs. 7.8%).”

In conclusion, Nemer and colleagues write, “in a high-volume, tertiary care institution, rates of successful LV lead delivery and major complications are similar between de novo transvenous CRT implantation and upgrade procedures. Furthermore, although VOD is a common finding during CRT upgrade that can increase procedural complexity, alternative management strategies are effective without excess risk of complications. Routine performance of venography before CRT upgrade may aid in procedural planning and execution of these strategies.”

They add that randomised controlled trials are still needed to more rigorously assess principles associated with CRT upgrade, particularly as such cases account for more than one-third of the procedural population.

Speaking to Cardiac Rhythm News, the study’s corresponding author, Daniel Cantillon (Cleveland Clinic, Cleveland, USA), said: “Concern for excess procedural risk with CRT upgrades over initial implants led some physicians to implant the third lead up front for patients with borderline CRT indications but in need of a pacemaker right away. Our study suggests that you safely upgrade the patient later on if there’s disease progression. The key is being able to deal with VOD in about a quarter of such patients using advanced techniques, which is what our centre was able to accomplish. On the other hand, pursuing CRT pacing initially among patients with borderline candidacy can sometimes paradoxically make them worse, in addition to accelerating battery depletion. So there are times when it’s best to hold off on CRT and go only with a single or dual chamber pacemaker up front.”


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