Part 3 of 6 in Circle CVI's Structural Heart series. Every Scan. One Plan. One Platform.

Ask who plans a structural heart case and you will usually hear the name of a physician. Ask what the plan is made of and you arrive somewhere else: a centralized 3D lab, a queue of studies covering three different procedures, and an analyst doing the measurement work that everyone downstream treats as fact.



That work is the most standardized thing in the structural program and the least discussed.

Three procedures, three anatomies, three sets of rules

The structural caseload does not divide neatly. A 3D lab supporting a full program handles aortic, mitral and left atrial appendage work in the same week, and the three have almost nothing in common beyond the scanner.

Aortic planning turns on annulus area and perimeter, coronary heights, calcification distribution, and access. The SCCT expert consensus covers the full sequence, and the ESCR consensus adds a reporting template for it.

Mitral planning turns on something else entirely. The predicted neo-LVOT determines whether transcatheter mitral valve replacement is safe at all, and the thresholds are tight. A registry of 194 patients found a predicted neo-LVOT below 170 mm² was 96.2 percent sensitive and 92.3 percent specific for LVOT obstruction, and current practice broadly treats 170 to 200 mm² as the range below which TMVR is not safe without a modification strategy. That is a measurement where being 20 mm² out changes the answer to a yes-or-no question.

LAAC planning turns on appendage morphology, ostial dimensions, device landing zone, and transseptal puncture orientation. The 2025 SCAI/HRS clinical practice guideline suggests obtaining pre-procedural TEE or CT rather than omitting it, a conditional recommendation on very low certainty evidence. The EHRA/EAPCI consensus is more forthcoming about why CT gets used: superior spatial resolution, detailed three-dimensional characterization of appendage anatomy, accurate sizing, and non-invasive acquisition. Delayed-acquisition CT reaches 100 percent sensitivity and 98 to 100 percent specificity for appendage thrombus.

One analyst. Three anatomies. Often three applications.

Standardization is the product

The 3D lab exists because a centralized reader produces a more consistent measurement than a distributed one. The evidence agrees: in a study of repeated annulus measurement, moving from a single reader to a multi-reader strategy cut device-size disagreement from 22 to 26 percent down to 5 to 10 percent.

Centralization delivers that only if the method is genuinely the same each time. Which is where the tooling starts to matter more than it looks like it should. Comparing two established planning packages on the same 100 patients, mean annulus area differed significantly between them, 482 mm² against 464 mm², along with perimeter and both coronary heights. A lab running one package for aortic and another for mitral is not running one standard. It is running two, and the report does not say which.

There is also the question of how much correction the automation needs. In that same comparison, accepting the fully automated output without review would have changed prosthesis size in 18 percent of patients. Reviewing and correcting the contours brought it to 4 percent. The lab's value is concentrated precisely in that gap.

What the LAAC evidence actually shows

LAAC is the procedure where planning software has been tested most rigorously, and the results are worth knowing accurately rather than in the version that appears on a slide.

PREDICT-LAA randomized 200 patients to standard planning or CT simulation-based planning. Its primary composite endpoint was not met, at a relative risk of 0.69 with a confidence interval crossing one and a p-value of 0.08. That is the honest headline and it should be stated first. The secondary endpoints are where the operational case sits: procedure time fell from 55.2 to 45.1 minutes, fluoroscopy time from 17.6 to 12.5 minutes, contrast volume from 80 to 59 mL, and the proportion of cases requiring more than three device repositionings dropped from 22.7 percent to 10.0 percent.

A 2026 meta-analysis across six studies and 978 patients found procedure time shorter by 13.29 minutes with CCTA planning and device resizing reduced at a relative risk of 0.42, with implantation success modestly improved. Contrast and radiation dose showed no significant difference. A separate meta-analysis reached a less favorable conclusion on implantation success, and anyone citing this literature should acknowledge that the two disagree.

The cleanest single finding comes from a subanalysis nested inside a randomized trial. Among 219 LAAC procedures preceded by CT, operators unblinded to the CT achieved short-term procedural success in 93.5 percent of cases against 81.1 percent for blinded operators, an adjusted odds ratio of 2.76. The blinding was not itself randomized, so this is association rather than causation. It is still the most direct evidence available that the planning work changes what happens in the lab.

The measurement the analyst produces is not documentation. It is a variable in the procedure.

Fewer clicks is more cases

Post-processing time is the constraint the 3D lab lives inside, and it is a documented one. A systematic appraisal of 440 imaging studies found that 48.3 percent would increase radiologist workload against 4.5 percent that would reduce it, with increased post-processing time named among the dominant mechanisms.

Reducing that time is not about the analyst working faster. It is about removing the repetitive placement work that produces neither insight nor variance reduction. In cvi42, assisted annulus and landmark detection across the Interventional Planning Suite covering aortic, mitral and LAAC removes 80 to 100 clicks from a typical case, by Circle's own measurement. Semi-automated measurement in a comparable published setting cut reading time roughly in half, from 3.14 minutes to 1.50, while producing an identical area-derived prosthesis size in 96 percent of cases for an experienced reader.

The analyst still reviews and corrects every contour. That is the part that carries the value, and it is the part that survives when the clicking goes away.

One platform across the caseload

The argument for consolidating the 3D lab onto a single platform is not a preference for tidiness. It is that three applications produce three measurement standards, three training curves, three upgrade cycles, three output formats for the heart team to reconcile, and three sets of credentials.

cvi42 covers aortic, mitral and LAAC planning in one environment, alongside the cardiac CT and cardiac MR the same lab often supports. LAAC planning for WATCHMAN TruPlan was developed by Circle working directly with Boston Scientific, which is why the appendage workflow behaves like something designed around the device rather than adapted to it. Measurements populate a structured report and reach the reporting environment through PowerScribe One, DICOM SR or HL7.

One method, applied the same way to every case, with the physician review loop exactly where it was.

See the structural planning workflow in cvi42 →

Stay tuned for more on Structural Heart from the perspective of imaging lab directors and department heads, IT and PACS, and procurement and administration.