Abstract
Recent EACVI recommendations described the importance of limiting cardiovascular imaging during the COVID-19 pandemic in order to reduce virus transmission, protect healthcare professionals ...from contamination, and reduce consumption of personal protective equipment. However, an elevated troponin remains a frequent request for cardiac imaging in COVID-19 patients, partly because it signifies cardiac injury due to a variety of causes and partly because it is known to convey a worse prognosis. The present paper aims to provide guidance to clinicians regarding the appropriateness of cardiac imaging in the context of troponin elevation and myocardial injury, how best to decipher the mechanism of myocardial injury, and how to guide patient management.
In stable coronary artery disease (CAD), the prognostic interaction between clinical variables and treatment appropriateness based on anatomic/functional phenotype needs to be evaluated.
1585 ...consecutive patients underwent myocardial perfusion scintigraphy and coronary angiography within 90 days. Obstructive CAD (> 70% stenosis) with downstream moderate-to-severe ischemia (> 10%) was considered significant. Coronary revascularization was considered appropriate if all hemodynamically significant lesions were revascularized, while medical therapy only was deemed appropriate in the absence of hemodynamically significant CAD.
Obstructive CAD and moderate-to-severe ischemia were documented in 1184 (75%) and 466 (29%) patients, respectively. Over mean follow-up of 4.7 ± 2.5 years, the primary endpoint (cardiac death and non-fatal myocardial infarction) occurred in 132 (8.2%) patients. Of patients with obstructive CAD, 797 (67%) were managed appropriately. Patients’ management was inappropriate in 389 patients, because either non-hemodynamically significant lesions were revascularized (50%, including 2 patients with non-obstructive lesions being inappropriately revascularized) or ischemia-causing CAD was left untreated (50%). At multivariate analysis, an inappropriate management (P < .001) was correlated with the primary endpoint, together with previous myocardial infarction (P = .009), lower ejection fraction (P < .001) and higher glucose levels (P < .001).
In stable CAD patients, management based on anatomic/functional phenotyping was correlated with a prognostic advantage at long-term follow-up.
Correlation between treatment categories and patients’ prognosis. A significantly higher event-rate was observed in patients where hemodynamically significant coronary lesions were left untreated—either because MT was not-adherently chosen or in the case of incomplete revascularization—than in those that were revascularized completely (17.6% vs 5.1%; P < .001). Conversely, the revascularization of non-hemodynamically significant CAD correlated with a higher event-rate than that of similar patients managed medically (13.8% vs 8.3%, P = .04). The event-rate of patients in whom coronary revascularization was performed in the presence of hemodynamically significant CAD (‘appropriate revascularization’) was similar to those with “No CAD/non-obstructive CAD” (5.1% vs 3.5%; P = NS).
▪
To better understand the mechanisms of left ventricular (LV) mechanical dyssynchrony (LVMD), we explored the relative contributions of QRS duration (QRSd), LV ejection fraction (EF), volumes and scar ...to LVMD measured by gated single-photon emission tomography in a population of consecutive patients with left bundle branch block (LBBB) and right bundle branch block (RBBB) compared to controls.
Myocardial perfusion imaging studies of 275 LBBB and 83 RBBB patients from three centers were analyzed. LVMD was defined as an abnormal phase bandwidth or phase standard deviation. Hospital and gender-specific normal values were obtained from 172 controls.
The prevalence of LVMD was 85 and 40% in LBBB and RBBB, respectively. Ejection fraction, scar severity, and LBBB morphology independently explained 70% of variance seen in PhaseBW. Ejection fraction had the highest area under the curve (AUC 0.918) in the receiver operating characteristics analysis of LVMD with an optimal cut-off of 47% (sensitivity 73% and specificity 98%). Notably, QRSd was not predictive.
LV mechanical dysfunction plays a greater role than conduction abnormality in the genesis of LVMD, a finding that is intriguing in the context of contemporary literature which suggests that QRSd is the parameter that is most predictive of CRT response.
Coronary angiography has been recommended in all patients with suspected chronic coronary syndrome and left ventricular ejection fraction (LVEF) ≤35%. The role of ischemia testing, for example, ...through stress-rest myocardial perfusion scintigraphy (MPS), for risk prediction is not well established.
Methods
We evaluated 1576 consecutive patients referred to MPS and stratified into 3 LV ejection fraction (LVEF) categories: ≤35%, 36–49%, and ≥ 50%.
Results
Patients with LVEF ≤35% were oldest, most often men, and with the highest likelihood of prior early (elective or urgent) coronary revascularization. They had also the highest values or summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS), as well as the highest frequency of significant coronary artery disease, and a greater number of diseased vessels. Follow-up: In this subgroup, 32 cardiovascular death or non-fatal myocardial infarction (MI) (21%), 35 all-cause deaths (22%), and 37 cardiovascular deaths, non-fatal MI, or late revascularizations (27%) were recorded with the shortest survival among all LVEF classes. SRS, SSS, and SDS had very low area under the curve values for the prediction of the 3 endpoints, with very high cut-offs, respectively. SRS and SSS cut-offs predicted a worse outcome in Cox regression models including the number of diseased vessels and early revascularization.
Conclusions
In patients with LVEF ≤35%, SRS and SSS are less predictive of outcome than in patients with better preserved systolic dysfunction, but their cut-offs retain independent prognostic significance from the number of vessels with significant stenoses and from early revascularization.
In the last decade, single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has been characterized by relevant technological innovations, with relevant improvements of ...both software and hardware settings, having the main goal of establishing systems with higher sensitivity and resolution, and with the potential to allow high quality images despite a more favorable dosimetry. In this regard, the introduction of dedicated cardiac cameras equipped with high-efficiency Cadmium–Zinc–Telluride (CZT) detectors have represented a milestone, allowing the unprecedented reduction of acquisition times. Moreover, the increased spatial resolution and count sensitivity and the possibility to acquire in list mode, like in PET exams, allow the quantification of myocardial blood flow that can potentially change the use of myocardial scintigraphy by CZT camera, in particular in difficult patients. The present article will review the existing evidence on SPECT imaging with dedicated CZT cameras, describing the technical characteristics of these cameras and shedding light on the latest fields of application of CZT imaging.
To evaluate cardiac sympathetic innervation in hypertensive patients with left ventricular (LV) hypertrophy (H) and aortic stenosis (AS) submitted to transcatheter aortic valve implantation (TAVI).
...Twenty-two hypertensive elders (82 ± 5 years) with severe AS and significant LVH (> 122 g·m−2 in women and > 149 g·m−2 in men) were compared with 14 patients with uncomplicated essential hypertension (HT) with similar degree of LVH and 10 controls. 123I-metaiodobenzylguanidine (MIBG) and 99mTc-tetrofosmin SPECT acquisitions were obtained to assess sympathetic innervation and LV perfusion. The innervation/perfusion mismatch score was taken as an indicator of cardiac sympathetic dysfunction. The imaging protocol was repeated 6 months after TAVI. Regional MIBG uptake was more heterogeneous in HT and AS patients than controls, and therefore, innervation/perfusion mismatch score was higher in both AS (9 ± 8) and HT (5 ± 2) than controls (1 ± 1, P < .001). On multivariate analysis, significant LVH was the major predictor of impaired LV sympathetic innervation (OR 19.45, 95% CI 1.87-201.92; P = .013). After TAVI, no differences in measures of LV sympathetic innervation were evident, although only a marginal LV mass reduction was observed (− 5.4 ± 2.4 g).
Cardiac sympathetic innervation is impaired in patients with LVH, either with AS or not, and is not impacted significantly by TAVI procedure.
Cadmium-zinc-telluride (CZT) SPECT allows the estimation of left ventricle myocardial volume (LVMV). We tested the clinical relevance of rest-stress LVMV changes (Δ LVMV) in detecting coronary artery ...disease (CAD, coronary stenosis > 70%), using CZT-SPECT.
We prospectively enrolled 512 consecutive patients with known or suspected CAD (mean age: 70.3 ± 9.2 years, 72% male) for stress-rest myocardial perfusion imaging (MPI, single-day stress-rest protocol). We quantified summed stress scores (SSS), summed rest scores, and summed difference scores, together with LVMV and ejection fraction (EF) after stress and at rest. All patients underwent coronary angiography within 30 days.
Two hundred seventy-two patients had CAD at coronary angiography. ΔLVMV ≤ 5 mL, corresponding to 6% of change from rest LVMV, was the best predictor of CAD (AUC = 0.831, 79% sensitivity, 82% specificity), irrespective of the stress protocol (dipyridamole or exercise stress) and independently of MPI-SSS, LV EF, and clinical history (P = 0.004). Integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were significant for the addition of ΔLVMV ≤ 5 mL (IDI = 6.1%, P < 0.0001; NRI = 29.7%, P = 0.02) to MPI-SSS, whereas the other parameters were not.
The evaluation of ΔLVMV using CZT-SPECT can improve the diagnostic accuracy in predicting the presence of CAD when added to conventional MPI.
A correlation between left ventricular (LV) dyssynchrony (LVD) and impaired myocardial sympathetic tone has been hypothesized. We sought to assess the interactions between regional LV sympathetic ...innervation, perfusion, and mechanical dyssynchrony.
Eighty-three patients underwent evaluation of LV perfusion and sympathetic innervation on 99mTc-tetrofosmin/123I-metaiodobenzylguanidine (123I-MIBG) imaging. The summed rest score and summed 123I-MIBG score (SS-MIBG) were computed. The extent of “innervation/perfusion” mismatch was defined as the number of denervated LV segments with relatively preserved perfusion. LVD was evaluated on phase analysis and the wall with latest mechanical activation identified.
LVD was revealed in 36 (43%) patients. Patients with LVD had more abnormal values of SRS (21 ± 9 vs 10 ± 8, P < 0.001) and SS-MIBG (29 ± 9 vs 17 ± 11, P < 0.001) than those without LVD. The presence of LVD also clustered with a higher burden of “innervation/perfusion” mismatch (P = 0.019). On per-wall analysis, LV walls with delayed mechanical activation showed a higher burden of “innervation/perfusion” mismatch (2.3 ± 1.4 segments) than normally contracting walls (1.3 ± 1.2 segments; P < 0.001). On multivariate analysis, the extent of “innervation/perfusion” mismatch was the only predictor of delayed mechanical activation (P = 0.029).
Patients with LVD show an elevated burden of “innervation/perfusion” mismatch that is concentrated at the level of the most dyssynchronous walls.
Myocardial perfusion imaging (MPI) performed on traditional single-photon emission computed-tomography cameras has been shown to have a sub-optimal accuracy in detecting multivessel coronary artery ...disease (CAD).
Six-hundred and ninety-five patients were submitted to MPI on a novel cadmium-zinc-telluride (CZT) camera and coronary angiography. A coronary stenosis >70% was considered obstructive. In every patient, the summed stress score (SSS) was computed. Moreover, the regional stress scores were also calculated for every coronary territory.
Four-hundred and forty-one patients had obstructive CAD in one (28%), two (19%), or three (17%) vessels. At per-patient analysis, the SSS showed a significant accuracy in detecting obstructive CAD (AUC 0.87, P < .001). Specifically, its accuracy was maintained also in patients with double (AUC 0.83; P < .001) or triple-vessels disease (AUC 0.79, P < .001), where CZT was able to correctly identify CAD extent in 64% of patients. On a per-vessel basis, CZT confirmed its high accuracy in detecting obstructive CAD (AUC 0.88, P < .001), independently from the involved coronary vessel.
MPI performed on a CZT camera is highly accurate in detecting obstructive CAD, independently from the coronary artery involved and the overall disease burden.
PDF
