Circulation: Cardiovascular Imaging最新文献

Background: The proposed cause of Takotsubo syndrome (TTS) includes coronary microvascular dysfunction. This study aimed to investigate coronary microvascular dysfunction and its recovery in patients with TTS using serial positron emission tomography myocardial perfusion imaging.

Methods: Patients with TTS who underwent cardiac positron emission tomography within 30 days of admission and at 6-month follow-up (May 2017-June 2023) were analyzed. Changes in positron emission tomography parameters, including extent of myocardial perfusion abnormality, left ventricular function, rest and stress myocardial blood flow (MBF), myocardial flow reserve, and coronary vascular resistance (CVR), were assessed from baseline to follow-up. In apical TTS, segmental analyses (basal, mid, distal segments, and apex) and intersegment differences were evaluated.

Results: Of 130 patients screened, 62 patients (median age, 70 years, 97% women) were included. After a median follow-up of 178 (121-282) days, global rest and stress MBF, myocardial flow reserve, and CVR significantly improved at follow-up (0.81-0.89 mL/min per gram, P=0.004; 1.56-2.61 mL/min per gram, P<0.001; 1.96-2.65, P<0.001; 52.0-36.2 mm Hg·min·g/mL, P<0.001, respectively). Among 53 patients with apical TTS, improvements in stress MBF, myocardial flow reserve, and CVR were noted in all myocardial segments (all P<0.001), including the basal segment; however, persistent MBF and CVR abnormalities were identified in the distal segment and apex, despite full recovery of left ventricular function.

Conclusions: Patients who underwent serial positron emission tomography perfusion imaging for TTS demonstrated reversible reductions in rest and stress MBF, myocardial flow reserve, and increases in CVR, suggestive of TTS-related coronary microvascular dysfunction and subsequent subtotal recovery. Coronary microvascular dysfunction extended beyond regions of wall motion abnormalities, and regional coronary flow abnormalities persisted in the medium term even after recovery of left ventricular function.

Background: Intramyocardial injection of hydrogel into myocardial infarction (MI) areas can reduce left ventricular remodeling and potentially increase angiogenesis post-MI. The radiotracer ^99mTc-Maraciclatide binds to activated alpha-v-beta-3 (αvβ3)-integrin, a key factor in angiogenesis, and can be used to evaluate myocardial angiogenesis. This study used multimodality imaging to assess the effects of imageable intramyocardial hydrogel delivery on left ventricular remodeling and angiogenesis after MI.

Methods: Fourteen pigs (N=14) underwent 90 minutes of balloon occlusion and reperfusion. Five days post-MI, they were randomized to receive either intramyocardial hydrogel (n=8) or control saline injections (n=6). Contrast cine-computed tomography was used to assess biomechanical changes before and after treatment (day 1, day 5, and day 12). ^99mTc-Maraciclatide uptake was measured with gamma well counting. Scar burden and angiogenesis were evaluated through histology.

Results: Both groups initially showed a decrease in ejection fraction and an increase in end-diastolic volume post-MI. Hydrogel delivery on day 5 led to a reduction in end-diastolic volume and improvement in left ventricular ejection fraction by day 12. The hydrogel group also exhibited decreased compensatory radial strain in remote myocardial segments, but decreased strain in the hydrogel myocardial segments. There was increased uptake of ^99mTc-maraciclatide in the infarct segments after hydrogel delivery, associated with increased αvβ3-integrin and factor VIII expression in the hydrogel treatment group on histology. However, there was no difference in regional inflammation or scar size between the groups.

Conclusions: Intramyocardial delivery of hydrogel early post-MI resulted in decreased left ventricular remodeling and increased αvβ3-integrin activation associated with an increase in angiogenesis.

Background: Stress perfusion cardiovascular magnetic resonance (CMR) is widely used to detect myocardial ischemia, mostly through visual assessment. Recent studies suggest that strain imaging at rest and during stress can also help in prognostic stratification. However, the additional prognostic value of combining both rest and stress strain imaging has not been fully established. This study examined the incremental benefit of combining these strain measures with traditional risk prognosticators and CMR findings to predict major adverse clinical events (MACE) in a cohort of consecutive patients referred for stress CMR.

Methods: This retrospective, single-center observational study included all consecutive patients with known or suspected coronary artery disease referred for stress CMR between 2016 and 2018. Fully automated machine learning was used to obtain global longitudinal strain at rest (rest-GLS) and global circumferential strain at stress (stress-GCS). The primary outcome was MACE, including cardiovascular death or hospitalization for heart failure. Cox models were used to assess the incremental prognostic value of combining these strain features with traditional prognosticators.

Results: Of 2778 patients (age 65±12 years, 68% men), 96% had feasible, fully automated rest-GLS and stress-GCS measurements. After a median follow-up of 5.2 (4.8-5.5) years, 316 (11.1%) patients experienced MACE. After adjustment for traditional prognosticators, both rest-GLS (hazard ratio, 1.09 [95% CI, 1.05-1.13]; P<0.001) and stress-GCS (hazard ratio, 1.08 [95% CI, 1.03-1.12]; P<0.001) were independently associated with MACE. The best cutoffs for MACE prediction were >-10% for rest-GLS and stress-GCS, with a C-index improvement of 0.02, continuous net reclassification improvement of 15.6%, and integrative discrimination index of 2.2% (all P<0.001).

Conclusions: The combination of rest-GLS and stress-GCS, with a cutoff of >-10% provided an incremental prognostic value over and above traditional prognosticators, including CMR parameters, for predicting MACE in patients undergoing stress CMR.

Background: Noninvasive imaging is widely used for both initial diagnosis and guided management of ischemic heart disease. Older adults and women with ischemic heart disease may have different responses to imaging and subsequent treatment outcomes compared to younger adults and men. We aimed to study the representation of older adults and women in randomized controlled trials of noninvasive imaging among patients with acute and stable chest pain.

Methods: We conducted a systematic search across PubMed, ClinicalTrials.gov, and guidelines to identify randomized controlled trials of noninvasive imaging-guided diagnosis and management for ischemic heart disease that were published between 2002 and 2023. Participation-to-prevalence ratio (PPR) was estimated for age subgroups of <65, 65 to 74, ≥75 years, and women. PPR of <0.8, 0.8 to 1.2, and >1.2 indicated underrepresentation, appropriate representation, and overrepresentation, respectively.

Results: Among 53 randomized controlled trials, age and sex breakdown were available in 21 (n=35 503) and 53 (n=55 893) trials, respectively. The median age across all trials was 57.4 years (interquartile range, 55.0-60.2). Participants <65 years of age were overrepresented with a median PPR of 2.13 (interquartile range, 1.73-2.43), whereas those 65 to 74 years and ≥75 years of age were underrepresented with median PPRs of 0.74 (interquartile range, 0.56-0.83) and 0.21 (interquartile range, 0.11-0.33), respectively. Women were adequately represented with a median PPR of 1.2 (1.06-1.32).

Conclusions: Although women were appropriately represented, adults ≥65 years, especially those ≥75 years, were underrepresented in these trials. Future randomized controlled trials involving imaging for chest pain should target enrollment of older adults to improve generalizability of results to this population.

Background: The relative flow reserve (RFR) derived from quantitative myocardial perfusion imaging is the ratio of absolute myocardial perfusion in a stenotic to normally perfused area and is considered the noninvasive equivalent of fractional flow reserve (FFR). In patients with prior coronary artery disease (CAD), detecting hemodynamically significant CAD using hyperemic myocardial blood flow (hMBF) is complicated by diffuse CAD and microvascular disease. In these patients, RFR may improve the diagnostic performance of myocardial perfusion imaging. Therefore, we studied the diagnostic value of RFR over hMBF in patients with prior CAD.

Methods: The PACIFIC-2 trial (functional stress imaging to predict abnormal coronary FFR) included symptomatic patients with prior myocardial infarction and/or percutaneous coronary intervention who prospectively underwent [¹⁵O]H₂O positron emission tomography perfusion imaging and invasive coronary angiography with 3-vessel FFR. RFR was assessed using positron emission tomography in an overall cohort incorporating all trial patients, and an optimal cohort of patients with angiographic 1- or 2-vessel disease (diameter stenosis ≥50%) and a nonstenotic reference vessel (diameter stenosis <30%). RFR was calculated as the ratio between the lowest to highest regional hMBF (overall cohort), or the lowest hMBF of a stenotic to the reference area (optimal cohort). Position emission tomography-derived flow indices were referenced by invasive FFR (≤0.80 deemed hemodynamically significant).

Results: The overall cohort included 187 patients (63±9.3 years, 36 [19%] female), and the optimal cohort 80 patients (62±9.6 years, 19 [24%] female). Significant CAD was present in 87 (47%) and 43 (54%) patients, respectively. Correlations between RFR and FFR were 0.42 and 0.52 (P<0.001 for both). C statistics for hMBF and RFR were comparable in the overall (0.81 versus 0.78; P=0.288) and the optimal cohort (0.79 versus 0.82; P=0.512).

Conclusions: RFR proves clinically applicable, even without specific patient selection and knowledge of the coronary anatomy. However, RFR does not outperform absolute hyperemic myocardial perfusion for detecting FFR-defined significant CAD in patients with prior CAD and recurrence of symptoms.