Clinical Outcomes Based on Coronary Computed Tomography-Derived Fractional Flow Reserve and Plaque Characterization

Favorable impact of FFRCT on myocardial revascularization outcomes: Results from an observational real-world registry

BACKGROUND

Coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFRCT) strategy significantly decreases unnecessary invasive coronary angiography and refines the appropriateness of revascularization decision. The present study aimed to evaluate how FFRCT guided - strategy impacts outcomes postrevascularization.

METHODS

We included patients with suspected obstructive coronary artery disease (OCAD in a registry from 2013 to 2021. FFRCT entered Heart-Team decision from 2017. Propensity score adjusted Cox - and logistic - regression analyzed FFRCT's impact on post- revascularization major adverse cardiovascular events (MACE) and myocardial injury (PMI).

RESULTS

Among 7541 patients, 1601 had suspected OCAD. 559 patients underwent revascularization: 69.0 % PCI, 29.7 % CABG and 1.2 % both. 252(45.1 %) patients underwent FFRCT. Over 4.4 ± 2.2 years, 137(24.5 %) patients experienced MACE. FFRCT was associated with a trend toward reduced MACE (HR 0.736, 95 % CI 0.513-1.055, p = 0.095) and significantly reduced all-cause mortality (HR 0.476, 95 % CI 0.230-0.985, p = 0.046). In the post-2017 cohort (413 patients, follow-up 3.7 ± 1.5 years), FFRCT significantly reduced MACE (HR 0.610, 95 % CI 0.390-0.954, P = 0.030) and all-cause mortality (HR 0.285, 95 % CI 0.104-0.779, P = 0.014). In CABG patients, FFRCT was associated with lower PMI incidence (5.3 % vs. 15.6 %, p = 0.044). Multivariable analysis revealed no significant association between FFRCT use and PMI.

CONCLUSIONS

Revascularization decision-making with FFRCT translates into better post-revascularization outcomes, primarily by reducing MACE through lower mortality. There was no clear impact on PMI. These findings suggests that FFRCT's value lies indeed in improving patient selection for revascularization, but warrants further confirmation in randomized clinical trials.

Temporal changes in PET myocardial flow reserve: Implications for cardiovascular outcomes

BACKGROUND

The usefulness of serial measurements of myocardial flow reserve (MFR) has received limited study outside of transplant vasculopathy. We describe the trends of myocardial blood flow and perfusion over time in patients undergoing positron emission tomography (PET) myocardial perfusion imaging (MPI) for the evaluation of coronary artery disease, and their association with cardiovascular outcomes.

METHODS

We retrospectively analyzed data from 474 patients without a history of heart transplant who underwent serial PET MPI (N = 948 studies) for the evaluation of coronary artery disease at Yale New Haven Hospital between 2016 and 2022. Patients were categorized according to MFR trajectory (low to low, low to high, high to low, high to high). Long-term major adverse cardiovascular events (MACE), defined as death or myocardial infarction, were analyzed with the Kaplan-Meier method and Cox regression. Log-likelihood, C-statistic and net reclassification were used to assess model performance.

RESULTS

The median interval time between tests was 776 days (IQR: 497-1058). The most common indications for the first and second PET were chest pain and dyspnea. MFR was similar in serial exams (2.1 [1.7, 2.6] vs 2.1 [1.7, 2.5], P = .75), but rest (1 [.8, 1.3] vs .9 [.7, 1] P < .01) and stress flows (2.1 [1.6, 2.8] vs 1.8 [1.4, 2.2], P < .01) were both reduced on the second PET. MFR increased in patients with revascularization between tests (N = 62 patients) (1.6 [1.3, 2.0] vs 1.7 [1.2, 2.2], P = .04). During a median follow-up time of 17 [8,28] months, the rate of MACE was 12% (51 events) and was higher in the low-to-low and low-to-high categories in multivariable analysis. The model including serial MFR and perfusion performed better than the baseline model including traditional clinical risk factors in terms of the likelihood ratio and C-statistic (from .74 to .80, P = .04).

CONCLUSIONS

In conclusion, our findings suggest that the serial assessment of MFR and perfusion may improve risk stratification beyond traditional clinical risk factors.

Predictors for Vulnerable Plaque in Functionally Significant Lesions

BACKGROUND

Vulnerable plaque presents prognostic implications in addition to functional significance.

OBJECTIVES

The aim of this study was to identify relevant features of vulnerable plaque in functionally significant lesions.

METHODS

In this multicenter, prospective study conducted across 5 countries, including patients who had invasive fractional flow reserve (FFR) ≤0.80, a total of 95 patients with available pullback pressure gradient (PPG) and plaque analysis on coronary computed tomographic angiography and optical coherence tomography were analyzed. Vulnerable plaque was defined as the presence of plaque rupture or thin-cap fibroatheroma on optical coherence tomography. Among the 25 clinical characteristics, invasive angiographic findings, physiological indexes, and coronary computed tomographic angiographic findings, significant predictors of vulnerable plaque were identified.

RESULTS

Mean percentage diameter stenosis, FFR, and PPG were 77.8% ± 14.6%, 0.66 ± 0.13, and 0.65 ± 0.13, respectively. Vulnerable plaque was present in 53 lesions (55.8%). PPG and FFR were identified as significant predictors of vulnerable plaque (P < 0.05 for all). PPG >0.65 and FFR ≤0.70 were significantly related to a higher probability of vulnerable plaque after adjustment for each other (OR: 6.75 [95% CI: 2.39-19.1]; P < 0.001] for PPG >0.65; OR: 4.61 [95% CI: 1.66-12.8]; P = 0.003 for FFR ≤0.70). When categorizing lesions according to combined PPG >0.65 and FFR ≤0.70, the prevalence of vulnerable plaque was 20.0%, 57.1%, 66.7%, and 88.2% in the order of PPG ≤0.65 and FFR >0.70, PPG ≤0.65 and FFR ≤0.70, PPG >0.65 and FFR >0.70, and PPG >0.65 and FFR ≤0.70 (P for trend < 0.001), respectively.

CONCLUSIONS

Among low-FFR lesions, the presence of vulnerable plaque can be predicted by PPG combined with FFR without additional anatomical or plaque characteristics. (Precise Percutaneous Coronary Intervention Plan [P3] Study; NCT03782688).

Prognostic Significance of Computed Tomography-Derived Fractional Flow Reserve for Long-Term Outcomes in Individuals With Coronary Artery Disease

BACKGROUND

Data on the predictive value of coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) for long-term outcomes are limited.

METHODS AND RESULTS

A retrospective pooled analysis of individual patient data was performed. Deep-learning-based CT-FFR was calculated. All patients enrolled were followed-up for at least 5 years. The primary outcome was major adverse cardiovascular events. The secondary outcome was death or nonfatal myocardial infarction. Predictive abilities for outcomes were compared among 3 models (model 1, constructed using clinical variables; model 2, model 1+coronary computed tomography angiography-derived anatomical parameters; and model 3, model 2+CT-FFR). A total of 2566 patients (median age, 60 [53-65] years; 56.0% men) with coronary artery disease were included. During a median follow-up time of 2197 (2127-2386) days, 237 patients (9.2%) experienced major adverse cardiovascular events. In multivariable-adjusted Cox models, CT-FFR≤0.80 (hazard ratio [HR], 5.05 [95% CI, 3.64-7.01]; P<0.001) exhibited robust predictive value. The discriminant ability was higher in model 2 than in model 1 (Harrell's C-statistics, 0.79 versus 0.64; P<0.001) and was further promoted by adding CT-FFR to model 3 (Harrell's C-statistics, 0.83 versus 0.79; P<0.001). Net reclassification improvement was 0.264 (P<0.001) for model 2 beyond model 1. Of note, compared with model 2, model 3 also exhibited improvement (net reclassification improvement=0.085; P=0.001). As for predicting death or nonfatal myocardial infarction, only incorporating CT-FFR into model 3 showed improved reclassification (net reclassification improvement=0.131; P=0.021).

CONCLUSIONS

CT-FFR provides strong and incremental prognostic information for predicting long-term outcomes. The combined models incorporating CT-FFR exhibit modest improvement of prediction abilities, which may aid in risk stratification and decision-making.

Cardiac Computed Tomography Angiography in the Evaluation of Coronary Artery Disease: An Interventional Perspective

Cardiac computed tomography angiography (CCTA) has become the gold standard for noninvasive anatomic assessment of the coronary arteries. With high positive predictive value and even higher negative predictive value, CCTA allows for rapid determination of the presence or absence of coronary plaque and triage of patients' need for further invasive evaluation and treatment. From an interventional cardiologist's perspective, CCTA (more so than stress testing) is helpful in determining the need for invasive therapy. In conjunction with functional assessments, the anatomic evaluation from CCTA mirrors the anatomical assessment of a coronary angiogram more than any other noninvasive assessment. This allows for catheter selection, percutaneous coronary intervention preplanning, as well as additional decision making before the patient has entered the catheterization laboratory. This manuscript explores some of the more recent developments in noninvasive coronary angiography and discusses the use and utility of CCTA from an interventional cardiologist's perspective.

Noninvasive Coronary Physiological Assessment Derived From Computed Tomography

Identifying functional significance using physiological indexes is a standard approach in decision-making for treatment strategies in patients with coronary artery disease. Recently, coronary computed tomography angiography-based physiological assessments, such as computed tomography perfusion and fractional flow reserve derived from coronary computed tomography angiography (FFR-CT), have emerged. These methods have provided incremental diagnostic values for ischemia-causing lesions over anatomical stenosis defined solely by coronary computed tomography angiography. Clinical data have demonstrated their prognostic value in the prediction of adverse cardiovascular events. Several randomized controlled studies have shown that clinical use of FFR-CT can reduce unnecessary invasive procedures compared to usual care. Recent studies have also expanded the role of FFR-CT in defining target lesions for revascularization by acquiring noninvasive lesion-specific hemodynamic indexes like ΔFFR-CT. This review encompasses the current evidence of the diagnostic and prognostic performance of computed tomography-based physiological assessment in defining ischemia-causing lesions and adverse cardiac events, its clinical impact on treatment decision-making, and implications for revascularization.