Selective CDK7 Inhibition Suppresses Cell Cycle Progression and MYC Signaling While Enhancing Apoptosis in Therapy-resistant Estrogen Receptor-positive Breast Cancer

PURPOSE

Resistance to endocrine therapy (ET) and CDK4/6 inhibitors (CDK4/6i) is a clinical challenge in estrogen receptor (ER)-positive (ER+) breast cancer. Cyclin-dependent kinase 7 (CDK7) is a candidate target in endocrine-resistant ER+ breast cancer models and selective CDK7 inhibitors (CDK7i) are in clinical development for the treatment of ER+ breast cancer. Nonetheless, the precise mechanisms responsible for the activity of CDK7i in ER+ breast cancer remain elusive. Herein, we sought to unravel these mechanisms.

EXPERIMENTAL DESIGN

We conducted multi-omic analyses in ER+ breast cancer models in vitro and in vivo, including models with different genetic backgrounds. We also performed genome-wide CRISPR/Cas9 knockout screens to identify potential therapeutic vulnerabilities in CDK4/6i-resistant models.

RESULTS

We found that the on-target antitumor effects of CDK7 inhibition in ER+ breast cancer are in part p53 dependent, and involve cell cycle inhibition and suppression of c-Myc. Moreover, CDK7 inhibition exhibited cytotoxic effects, distinctive from the cytostatic nature of ET and CDK4/6i. CDK7 inhibition resulted in suppression of ER phosphorylation at S118; however, long-term CDK7 inhibition resulted in increased ER signaling, supporting the combination of ET with a CDK7i. Finally, genome-wide CRISPR/Cas9 knockout screens identified CDK7 and MYC signaling as putative vulnerabilities in CDK4/6i resistance, and CDK7 inhibition effectively inhibited CDK4/6i-resistant models.

CONCLUSIONS

Taken together, these findings support the clinical investigation of selective CDK7 inhibition combined with ET to overcome treatment resistance in ER+ breast cancer. In addition, our study highlights the potential of increased c-Myc activity and intact p53 as predictors of sensitivity to CDK7i-based treatments.

Endocrine Therapy Synergizes with SMAC Mimetics to Potentiate Antigen Presentation and Tumor Regression in Hormone Receptor-Positive Breast Cancer

Immunotherapies have yet to demonstrate significant efficacy in the treatment of hormone receptor-positive (HR+) breast cancer. Given that endocrine therapy (ET) is the primary approach for treating HR+ breast cancer, we investigated the effects of ET on the tumor immune microenvironment (TME) in HR+ breast cancer. Spatial proteomics of primary HR+ breast cancer samples obtained at baseline and after ET from patients enrolled in a neoadjuvant clinical trial (NCT02764541) indicated that ET upregulated β2-microglobulin and influenced the TME in a manner that promotes enhanced immunogenicity. To gain a deeper understanding of the underlying mechanisms, the intrinsic effects of ET on cancer cells were explored, which revealed that ET plays a crucial role in facilitating the chromatin binding of RelA, a key component of the NF-κB complex. Consequently, heightened NF-κB signaling enhanced the response to interferon-gamma, leading to the upregulation of β2-microglobulin and other antigen presentation-related genes. Further, modulation of NF-κB signaling using a SMAC mimetic in conjunction with ET augmented T-cell migration and enhanced MHC-I-specific T-cell-mediated cytotoxicity. Remarkably, the combination of ET and SMAC mimetics, which also blocks prosurvival effects of NF-κB signaling through the degradation of inhibitors of apoptosis proteins, elicited tumor regression through cell autonomous mechanisms, providing additional support for their combined use in HR+ breast cancer.

SIGNIFICANCE

Adding SMAC mimetics to endocrine therapy enhances tumor regression in a cell autonomous manner while increasing tumor immunogenicity, indicating that this combination could be an effective treatment for HR+ patients with breast cancer.

Long-term clinical outcomes and healthcare utilization of sickle cell disease patients with COVID-19: A 2.5-year follow-up study

OBJECTIVES

This study investigated whether patients with sickle cell disease (SCD) had elevated risk of worse long-term clinical outcomes and healthcare utilization 2.5 years post-SARS-CoV-2 infection.

METHODS

This study consisted of 178 patients with SCD who tested positive for COVID-19 between February 1, 2020 and January 30, 2022 in a major academic health system in New York City. The control cohort consisted of two-to-one matches of 356 SCD patients without a COVID-19 positive test. The last follow-up was July 18, 2022. The primary outcome was mortality. Secondary outcomes were annualized emergency department visits due to pain, pain hospital admission, length of stay due to pain, acute chest syndrome, episodic transfusion, and episodic exchange transfusion.

RESULTS

There was no significant difference in mortality between SCD patients with and without COVID-19 (p > .05). There were no significant differences in secondary outcomes between pre- and postpandemic (p > .05). There were also no significant differences in these outcomes between SCD patients with and without COVID-19 (p > .05). SCD care utilization was not significantly associated with COVID-19 hospitalization status (p > .05).

CONCLUSIONS

SCD patients with SARS-CoV-2 infection incurred no additional risk of worse long-term outcomes compared to matched controls of SCD patients not infected by SARS-CoV-2.

The Use of Radiomic Features to Predict Human Papillomavirus (HPV) Status in Head and Neck Tumors: A Review

Head and neck cancers represent a significant source of morbidity and mortality across the world. The individual genetic makeup of each tumor can help to determine the course of treatment and can help clinicians predict prognosis. Non-invasive tools to determine the genetic status of these tumors, particularly p16 (human papillomavirus (HPV)) status could prove extremely valuable to treating clinicians and surgeons. The field of radiomics is a burgeoning area of radiology practice that aims to provide quantitative biomarkers that can be derived from radiological images and could prove useful in determining p16 status non-invasively. In this review, we summarize the current evidence for the use of radiomics to determine the HPV status of head and neck tumors. .

Abstract GS3-07: GS3-07 Clonal evolution and mechanisms of acquired resistance to CDK4/6 inhibitors in ER-wild type and ER-mutant breast cancer

Background Despite the remarkable activity of CDK4/6 inhibitors (CDK4/6i) in the treatment of estrogen receptor positive (ER+) metastatic breast cancer (BC), most patients eventually develop resistance to these drugs. The ctDNA analysis of the PALOMA-3 trial showed that the estrogen receptor (ER) mutation Y537S is a potential mechanism of acquired resistance to the combination of endocrine therapy (ET) with CDK4/6i. To date, the role of the ER mutations in the clonal evolution and the mechanisms of acquired resistance to CDK4/6i is unknown. Moreover, it is not known if the development of resistance to CDK4/6i in the presence or absence of ER mutations is due to the expansion of pre-existing resistant clones or to the de novo acquisition of resistance mechanisms. Methods To explore the clonal evolution and the mechanisms of resistance to CDK4/6i in ER-wild type (ER-WT) and ER-mutant (ER-Mut) BC, we transduced doxycycline (DOX)-inducible Y537S ER-Mut MCF7 cells with the ClonTracer library, a high-complexity DNA barcode library, and cultured the barcoded cells without DOX (MCF7), or with DOX to induce the expression of the Y537S ER mutation (MCF7-YS). To develop Palbociclib (Palbo)-resistant (PDR) and Abemaciclib (Abema)-resistant (ABR) cell models, the barcoded MCF7 and MCF7-YS cells were passaged in culture with increasing concentrations of Palbo and Abema until the acquisition of resistance. The clonal dynamics and the molecular characteristics of the PDR and ABR models were investigated by barcode sequencing, whole-exome sequencing (WES), bulk and single cell RNA sequencing (RNAseq) and protein analyses. Finally, using an ER-Mut barcoded mice model, we compared the in vitro clonal evolution of ER-Mut CDK4/6i-resistant cells with the in vivo clonal evolution of ER-Mut metastases. Results The analysis of the barcodes revealed that during the acquisition of resistance to either Palbo or Abema there is a strong clonal selection of pre-existing resistant clones. The PDR clones were different in the presence of the Y537S mutation versus WT-ER. In contrast, the clones enriched in the ABR cells were comparable between WT and mutant ER. Furthermore, the ER mutations led to decreased diversity of the enriched clones in the PDR but not in the ABR cells. Interestingly, the barcodes enriched in the PDR and ABR models did not overlap. Unsupervised analyses showed that the samples clustering based on the barcodes fractions and the mutations were similar, suggesting that the clonal selection was driven by cellular populations with specific mutational landscapes. All the ER-WT and ER-Mut resistant models had different transcriptional profiles and by single-cell RNAseq showed various degrees of intra-sample heterogeneity. At the protein level, the PDR and the ABR cells displayed downregulation of ER, Rb and p27 and upregulation of p21. In the ER-Mut conditions Cyclin D1 was upregulated in the PDR cells, while Cyclin E was upregulated in the ABR cells. Finally, the barcode sequencing of the mice metastases revealed that the clonal selection in ER-Mut metastases and in ER-Mut CDK4/6i-resistant cells is different. Conclusion Our study suggests that the development of resistance to CDK4/6i is due to the selection of pre-existing resistant clones. We also demonstrate that the expression of the Y537S ER mutation impacts the clonal evolution and the mechanisms of acquired resistance to Palbo but not to Abema. Finally, we show that the clonal evolution and mechanisms are disparate in Palbo and Abema resistance. These results support the addition of a third drug to CDK4/6i and ET, early in treatment, to delay the selection of pre-existing resistant clones and prolong the response to treatment and highlight differences between Palbo and Abema.

Citation Format: Cristina Guarducci, Simona Cristea, Avery Feit, Sergey Naumenko, Agostina Nardone, Wen Ma, Douglas Russo, Gabriella Cohen Feit, Ariel Feiglin, Francisco Hermida-Prado, Shira Sherman, Myles Brown, Franziska Michor, Rinath Jeselsohn. GS3-07 Clonal evolution and mechanisms of acquired resistance to CDK4/6 inhibitors in ER-wild type and ER-mutant breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS3-07.

A Distinct Chromatin State Drives Therapeutic Resistance in Invasive Lobular Breast Cancer

Most invasive lobular breast cancers (ILC) are of the luminal A subtype and are strongly hormone receptor-positive. Yet, ILC is relatively resistant to tamoxifen and associated with inferior long-term outcomes compared with invasive ductal cancers (IDC). In this study, we sought to gain mechanistic insights into these clinical findings that are not explained by the genetic landscape of ILC and to identify strategies to improve patient outcomes. A comprehensive analysis of the epigenome of ILC in preclinical models and clinical samples showed that, compared with IDC, ILC harbored a distinct chromatin state linked to gained recruitment of FOXA1, a lineage-defining pioneer transcription factor. This resulted in an ILC-unique FOXA1-estrogen receptor (ER) axis that promoted the transcription of genes associated with tumor progression and poor outcomes. The ILC-unique FOXA1-ER axis led to retained ER chromatin binding after tamoxifen treatment, which facilitated tamoxifen resistance while remaining strongly dependent on ER signaling. Mechanistically, gained FOXA1 binding was associated with the autoinduction of FOXA1 in ILC through an ILC-unique FOXA1 binding site. Targeted silencing of this regulatory site resulted in the disruption of the feed-forward loop and growth inhibition in ILC. In summary, ILC is characterized by a unique chromatin state and FOXA1-ER axis that is associated with tumor progression, offering a novel mechanism of tamoxifen resistance. These results underscore the importance of conducting clinical trials dedicated to patients with ILC in order to optimize treatments in this breast cancer subtype.

SIGNIFICANCE

A unique FOXA1-ER axis in invasive lobular breast cancer promotes disease progression and tamoxifen resistance, highlighting a potential therapeutic avenue for clinical investigations dedicated to this disease. See related commentary by Blawski and Toska, p. 3668.

MYC drives aggressive prostate cancer by disrupting transcriptional pause release at androgen receptor targets

c-MYC (MYC) is a major driver of prostate cancer tumorigenesis and progression. Although MYC is overexpressed in both early and metastatic disease and associated with poor survival, its impact on prostate transcriptional reprogramming remains elusive. We demonstrate that MYC overexpression significantly diminishes the androgen receptor (AR) transcriptional program (the set of genes directly targeted by the AR protein) in luminal prostate cells without altering AR expression. Analyses of clinical specimens reveal that concurrent low AR and high MYC transcriptional programs accelerate prostate cancer progression toward a metastatic, castration-resistant disease. Data integration of single-cell transcriptomics together with ChIP-seq uncover an increase in RNA polymerase II (Pol II) promoter-proximal pausing at AR-dependent genes following MYC overexpression without an accompanying deactivation of AR-bound enhancers. Altogether, our findings suggest that MYC overexpression antagonizes the canonical AR transcriptional program and contributes to prostate tumor initiation and progression by disrupting transcriptional pause release at AR-regulated genes.

Inhibition of EZH2 transactivation function sensitizes solid tumors to genotoxic stress

Drugs that block the activity of the methyltransferase EZH2 are in clinical development for the treatment of non-Hodgkin lymphomas harboring EZH2 gain-of-function mutations that enhance its polycomb repressive function. We have previously reported that EZH2 can act as a transcriptional activator in castration-resistant prostate cancer (CRPC). Now we show that EZH2 inhibitors can also block the transactivation activity of EZH2 and inhibit the growth of CRPC cells. Gene expression and epigenomics profiling of cells treated with EZH2 inhibitors demonstrated that in addition to derepressing gene expression, these compounds also robustly down-regulate a set of DNA damage repair (DDR) genes, especially those involved in the base excision repair (BER) pathway. Methylation of the pioneer factor FOXA1 by EZH2 contributes to the activation of these genes, and interaction with the transcriptional coactivator P300 via the transactivation domain on EZH2 directly turns on the transcription. In addition, CRISPR-Cas9-mediated knockout screens in the presence of EZH2 inhibitors identified these BER genes as the determinants that underlie the growth-inhibitory effect of EZH2 inhibitors. Interrogation of public data from diverse types of solid tumors expressing wild-type EZH2 demonstrated that expression of DDR genes is significantly correlated with EZH2 dependency and cellular sensitivity to EZH2 inhibitors. Consistent with these findings, treatment of CRPC cells with EZH2 inhibitors dramatically enhances their sensitivity to genotoxic stress. These studies reveal a previously unappreciated mechanism of action of EZH2 inhibitors and provide a mechanistic basis for potential combination cancer therapies.

Effect of Positioning of the Region of Interest on Bone Density of the Hip

BACKGROUND

Large changes in positioning of the global region of interest (ROI) influence the measurement of bone mineral density (BMD) in the hip and forearm regions. However, it is unknown whether minor shifts in the positioning of the bottom of the global hip ROI affect the measurement of total hip BMD.

METHODS

The hip BMDs of 40 clinical densitometry patients were analyzed at baseline with the bottom of the global hip ROI positioned as usual, 10 mm distal to the base of the lesser trochanter (position 0). Then the hip was reanalyzed by shifting the bottom of the global hip ROI 1 mm proximally 10 times (positions +1 through +10) and then by shifting the bottom of the global hip ROI 1 mm distally 10 times (positions -1 through -10). The significance of the differences between mean values at the various distances from baseline was assessed using a Wilcoxon signed-rank test.

RESULTS

The mean total hip area, bone mineral content and BMD decreased as the bottom of the global hip ROI was shifted proximally; the decrease was significant when shifted by even 1 mm (p < 0.001). The mean total hip area, bone mineral content and BMD increased as the bottom of the global hip ROI was shifted distally; the increase was significant when shifted by even 1 mm (p < 0.001). The change in BMD with each 1 mm shift was uniform across the range studied from positions +10 through -10, and was approx 0.54%/mm. When the least significant change was based on 40 pairs of measurements, where each pair was comprised of the baseline scan and the same scan at -1 position, the least significant change was 0.01 g/cm².

CONCLUSIONS

The BMD of the total hip is sensitive to even minor changes in the positioning of the bottom of the global hip ROI. Although a 1 mm change in the bottom of the global hip ROI positioning would make little difference in the reported T-score, it could easily affect the determination of significance in changes in BMD over time.

Combination of fulvestrant and chemotherapy in ESR1 Y537S mutant breast cancer cells and potential synergy mechanism related to p53 wildtype

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Background: The acquisition of ligand-independent ESR1 mutations during endocrine therapy in metastatic ER+ breast cancer is a common mechanism of resistance to endocrine treatment, particularly aromatase inhibitors, and found in more than 30% of patients with metastatic ER+ breast cancer. Our recent work showed that the ER mutations confer resistance to currently available endocrine treatments while promoting an aberrant ER transcriptional activity that drives metastases. These results underscore the importance of targeting the ESR1 mutations even after the development of endocrine resistance. We hypothesized that during chemotherapy treatment, the ESR1 mutations remain an important driver of tumor growth and metastases and therefore drugs targeting the ESR1 mutation could enhance the efficacy of chemotherapy. In this study we investigated the combination of chemotherapy with the selective estrogen receptor degrader in the presence of WT and mutant ER. Methods: We performed synergy studies testing the combination of fulvestrant with chemotherapy treatments commonly used in ER+ metastatic breast cancer including 5FU (representing capecitabine), adriamycin and paclitaxel using MCF7 and T47D breast cancer cell lines engineered to express doxycycline inducible Y537S-ESR1 mutation. Results: We found that in MCF7 cells the combination of chemotherapy and fulvestrant was synergistic and the synergy was augmented with the induction of the Y537S mutation. In contrast, there was no synergy in T47D cells that harbor a P53 mutation. We confirmed that the synergistic activity of fulvestrant with chemotherapy is dependent on P53 by generating P53 knock-out MCF7 cells using CRISPR-cas9. Additionally, cell cycle and apoptosis analyses showed that the synergistic activity was mainly due to increased effects on G1 arrest rather than apoptosis. Conclusions: Our study indicates that chemotherapy and fulvestrant are synergistic in ER+ breast cancer and the synergy is increased in the presence of the Y537S ESR1 mutation and is dependent on P53 activity. These results support a clinical trial testing the addition of fulvestrant or other novel selective estrogen receptor degraders in patients with metastatic ER+ breast cancer who are starting chemotherapy treatment.

Relationship between cytokine levels and coronary artery disease in women

Inflammation is thought to have a role in the pathogenesis of atherosclerotic coronary artery disease (CAD), and the measurement of markers of inflammation has been suggested to improve the identification of individuals at risk for this disease. The incidence of CAD in women is not accounted for by conventional risk factors, and the association of CAD and the antiinflammatory cytokine transforming growth factor beta1 (TGF-beta1) in this population is unknown. Associations among TGF-beta1, the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha), and CAD severity in inner city women were examined. Fifty-three women requiring angiography (mean age, 60.7 years) were stratified as having on of the following conditions: 0 vessel disease (VD) (n = 20), 1 (VD) (n = 10), 2 VD (n = 9), or 3 VD (n = 14). Fasting serum cytokine levels were determined by enzyme-linked immunosorbent assay. Serum TGF-beta1 was lower in patients with extensive disease (2 and 3 VD versus 0 and 1 VD). The lowest TGF-beta1 levels (<30 ng/mL) were in the 2 and 3 VD groups. In contrast, in the 0 and 1 VD groups, TGF-beta1 was above 41 ng/mL. Serum TGF-beta1 correctly classified the severity of CAD in 62.3% of patients, with a predictive threshold of 58 ng/mL by discriminant function analysis. TGF-beta1 may be a determinant of clinical events and outcome in CAD in women.

Use of intracoronary electrocardiography for detecting ST-T, QTc, and U wave changes during coronary balloon angioplasty

Intracoronary electrocardiography (IC-ECG) is a more sensitive method than surface ECG to detect electrical changes during percutaneous transluminal coronary angioplasty (PTCA). It also provides direct monitoring of ST-T segment, QTc intervals, and U-wave genesis during balloon inflation. These changes are reflective of myocardial ischemia. The authors studied the effect of transient myocardial ischemia on ST-T segment, QTc intervals, and U-wave appearance by comparing standard and perfusion balloon angioplasty. PTCA of left anterior descending artery was performed in 14 patients using the standard balloons and in 11 patients using the perfusion balloons. Patients with perfusion balloon angioplasty had less ST-T elevation (0.15 +/- 0.05 mV versus 1.04 +/- 0.19 mV, P < 0.001), less QTc-shortening intervals (0.01 +/- 0.02 seconds versus -0.05 +/- 0.04 seconds, P < 0.001), and less positive U waves (two versus nine). The authors concluded that balloon angioplasty with perfusion balloons is associated with less ischemia as reflected by ST-T, QTc-shortening intervals, and U-wave changes. There was more positive U-wave appearance with the standard balloon angioplasty, which implies more ischemia. In addition, QTc-shortening intervals are associated with the development of U waves during standard balloon angioplasty. These findings suggest that IC-ECG is a sensitive tool in detecting myocardial ischemia. IC-ECG may also help to clarify the nature of chest pain during PTCA in some patients. Like QT dispersion (QTd), QTc-shortening intervals and new U waves can have prognostic implications and additional studies are needed to define this role.

Recurrent right atrial thrombus after repair of ruptured sinus of valsalva aneurysm

Ruptured sinus of Valsalva aneurysm is a rare cardiac abnormality. Early surgical repair is indicated to prevent complications such as heart failure, infective endocarditis, arrhythmias, and thromboembolic events. The authors report an unusual case of recurrent right atrial thrombus after the surgical repair and closure of ruptured sinus of Valsalva aneurysm.

Fatal left main coronary artery embolism from aortic valve endocarditis following cardiac catheterization

Coronary artery embolization has been associated with sudden cardiac death. It is more commonly seen with aortic valve endocarditis. It manifests as acute myocardial ischemia or infarction, causing instability of the cardiac rhythm, which may be fatal. We report a patient with aortic valve endocarditis who had sudden cardiac death following coronary angiography. Autopsy revealed embolic occlusion of the left main coronary artery.

Successful percutaneous stenting of a right gastroepiploic coronary bypass graft using monorail delivery system: a case report

The right gastroepiploic artery (RGEA) is being successfully used as an arterial conduit in a selected group of patients undergoing coronary artery bypass graft surgery. However, myocardial ischemia may result due to spasm, occlusion, and stenosis of this graft. The anastamosis site at distal right coronary artery (RCA) or posterior descending artery (PDA) is the most common location for stenosis of an in situ gastroepiploic coronary bypass graft. Balloon angioplasty of such stenoses has been reported with optimal short-term results. Stent deployment would decrease the restenosis rate, so that repeat procedures could be minimized for these technically challenging lesions. We describe a case of successful deployment of a stent with monorail delivery system at the anastamotic site stenosis of an in situ gastroepiploic right coronary artery bypass graft. This percutaneous coronary intervention could prevent redo coronary artery bypass graft surgery. Cathet. Cardiovasc. Intervent. 49:197-199, 2000.

New hemoglobin substitutes

Blood transfusion is an essential and ubiquitous component of medical therapy. Despite careful screening and processing, allogeneic blood still carries a small but definable risk of the transmission of severe viral disease and the induction of immunological reactions. The logistics of its storage and transport continue to present a challenge, and its dependence on human donors will always keep it a scarce resource. It is not surprising that in the latter half of the 20th century efforts to develop blood substitutes have gained increasing momentum.

Takayasu's arteritis: an unusual manifestation--a case report

Takayasu's arteritis is a rare entity. The authors describe a case of a middle-aged woman with an atypical form of Takayasu's arteritis. This manifestation has not been described previously.

Successful percutaneous balloon mitral valvuloplasty in a patient with left atrial thrombus--a case report

Percutaneous balloon mitral valvuloplasty (PBMV) described by Inoue et al, is a safe FDA (Food and Drug Administration) approved procedure in patients with severe mitral stenosis. One of the contraindications of the procedure is presence of a left atrial thrombus; however, it has been reported that intense warfarin therapy may led to dissolution of the thrombus. The authors report a patient who was referred for PBMV and was found to have a left atrial thrombus. After intense warfarin therapy, successful PBMV was undertaken without complications.

ST-T alternans and myocardial ischemia

Previous studies using intracoronary electrocardiography have demonstrated that ST-T alternans can develop during standard balloon coronary angioplasty. Total occlusion with a large amount of myocardium in jeopardy is the postulated prerequisite. In this study, the authors used perfusion balloons instead of standard balloons, so coronary perfusion was maintained and ischemia was minimized. Fourteen patients with standard balloon technique and 11 patients with perfusion balloon technique were studied. The ST segment was less elevated during perfusion angioplasty (0.15 +/- 0.05 mV vs 1.04 +/- 0.19 mV, p<0.001). There were six (43%) patients with ST-T alternans with standard balloon technique compared with none in the perfusion balloon group (p<0.001). In this study, the authors found that there was less ischemia, less ST segment elevation, and lack of ST-T alternans on the intracoronary electrocardiogram during perfusion balloon angioplasty. These findings support the postulate that a large amount of ischemic myocardium is a prerequisite for ST-T alternans.

Rescue PTCA complicated by pulmonary artery rupture after tPA and abciximab

Since the introduction of pulmonary artery catheterization for hemodynamic monitoring, several complications associated with its use have been described. Pulmonary artery rupture is an infrequent complication of flow-directed pulmonary artery catheters. We report a case of pulmonary artery rupture complicating rescue PTCA in the presence of systemic platelet inhibition with abciximab (Reopro), anticoagulation, and thrombolytic therapy. With the increasing use of these medications in patients undergoing acute coronary interventions, particularly those patients requiring hemodynamic monitoring, this uncommon but potentially fatal complication may be seen more frequently.

Pulsus alternans in diastolic left ventricular dysfunction--a case report

Pulsus alternans is usually found in patients with reduced systolic ventricular function. We describe a patient with recurrent pulmonary edema, hypertension, bilateral renal artery stenosis, but with normal systolic function. Pulsus alternans was demonstrated in both pulmonary artery, right ventricle, and left ventricle pressures. After successful renal artery revascularization, the pulsus alternans disappeared. This case illustrates that pulsus alternans can be present with diastolic dysfunction of the left ventricle in the absence of systolic dysfunction.

DNA studies of limb-girdle muscular dystrophy type 2A in the Amish exclude a modifying mitochondrial gene and show no evidence for a modifying nuclear gene

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Cardiac catheterization and selective coronary angiography with tortuous aorta and anomalous coronary artery

The authors report a case of selective coronary angiography by use of a modified technique in a patient with tortuous iliac artery, distorted thoracic descending aorta, and anomalous left coronary artery. This approach to such anatomy can decrease the fluoroscopy time and reduce the likelihood of complications.

Pseudo-alternans of left ventricular end diastolic pressure. A case report

The authors report a case of left ventricular end diastolic pressure alternans without systolic alternans in a patient with bradycardia and tachypnea. This is an artifact due to the heart rate falling in a 2:1 ratio to the respiratory cycle. Alternation of left ventricular end diastolic pressure should be interpreted carefully in patients with bradycardia.

Combined dissection of the right coronary artery and right coronary cusp during coronary angiography

Dissection of coronary arteries during diagnostic coronary angiography is infrequent; dissection of the coronary cusp is extremely rare. The combination of coronary artery and coronary cusp dissection has not been reported previously. A case of right coronary artery dissection and right coronary cusp dissection during diagnostic coronary angiography is described.

Intracoronary ST-T alternans during coronary balloon angioplasty

To evaluate the presence and clinical significance of electrical alternans during PTCA, intracoronary electrocardiography (ic-ECG) was performed in 65 consecutive lesions. ST-T alternans, defined as a beat-to-beat difference in the ST elevation > or = 1 mm, was present in five lesions (7.7%), all in the proximal left anterior descending (LAD) coronary artery. The phenomenon was seen only after 130 sec (mean 174 +/- 57) of balloon inflation. Only two of the five showed ST-T alternans simultaneously on both surface and ic-ECG. One of five patients had premature ventricular contractions following ST-T alternans. Three of these five lesions required a second balloon inflation with duration of > or = 300 sec; there was no ST-T alternans on the second inflation in any of these lesions. We conclude: (1) the detection of ST-T alternans during PTCA is enhanced by use of ic-ECG, (2) electrical alternans during PTCA was seen only in proximal LAD lesions, implicating a large amount of ischemic myocardium as a requisite for the phenomenon, (3) electrical alternans is not immediate, requiring a certain duration of balloon occlusion and hence ischemia to occur, and (4) the absence of ST-T alternans during second balloon inflations suggests ischemic preconditioning may abolish this phenomenon.

Coronary artery fistula coexisting with a ventricular septal defect due to a penetrating gunshot wound

We describe a patient who survived a penetrating gunshot wound to the chest. Cardiac evaluation including echocardiography and cardiac catheterization revealed a coronary artery fistula and a ventricular septal defect. This combination has been rarely reported in patients with penetrating cardiac injury. Follow-up echocardiography performed 15 mo later showed persistent left-to-right shunt. This is the first case in the literature demonstrating the natural history of combined coronary artery fistula and ventricular septal defect without surgical correction.

Cardiac disease and nonorganic chest pain: factors leading to disability

Research has shown that many chest pain patients, without coronary artery disease, may suffer from panic disorder, hypochondriasis, depression, and/or multiple phobias. Some patients with coronary artery disease may also suffer from these disorders and are often unable to return to previous activity. In spite of good prognosis for longevity and acceptable exercise test results, a large proportion of these patients continue to be disabled by chest pain and/or chronic cardiac fears and demand constant medical attention. This study examined the psychiatric and behavioral symptomatology that differentiated four groups of patients experiencing chest pain: the able (active/working patient) with and without coronary artery disease, as determined by exercise thallium-201 studies, and the disabled (inactive/nonworking patient) with and without coronary artery disease. The results of the study indicated that the inactive patients, both with and without heart disease, suffered from a host of debilitating psychiatric conditions.

Anomalous origin of the right coronary artery above the left posterior sinus of Valsalva associated with a normal aortic valve. A case history

This case report describes a right coronary artery arising from the ascending aorta, above the left posterior sinus. Unlike previously reported cases, this was associated with a normal aortic valve. The clinical significance and approach during angiography are discussed.

Multiple balloon rupture during coronary angioplasty. A case report

The authors report a case of coronary angioplasty of the left anterior descending artery complicated by multiple balloon rupture. Various balloon types including polyethylene terephthalate and PE 600 (ACS) ruptured at low atmospheric pressure. During balloon rupture, a septal side branch was dissected with severe intimal staining. The authors postulate that a particular lesion morphology was responsible for balloon rupture. Approaches to such lesions using alternative coronary angioplasty techniques and newer technologies are discussed.

Late neovascularization of longstanding left ventricular mural thrombus--a case report

Serial coronary angiography done in a patient with left ventricular mural thrombus demonstrated abnormal neovascularity from the coronary artery to the left ventricle occurring eight to eighteen months after thrombus formation. This is the first case report describing such late neovascularization of left ventricular mural thrombus. The formation of coronary neovascularity to left ventricular mural thrombus need not occur in the early stage of the thrombus.

Internal mammary artery angiography should be a routine component of diagnostic coronary angiography

Left internal mammary artery (LIMA) angiography was performed with diagnostic coronary angiography in 130 cases for which the coronary findings made use of the LIMA as a bypass graft a consideration. In 98% of the cases the approach to LIMA angiography was femoral with a 5F LIMA catheter first directed into the proximal subclavian and then advanced over a guidewire placed into the distal subclavian well beyond the origin of the LIMA. After withdrawing the wire the catheter was brought proximally to selectively cannulate and visualize the LIMA with nonionic contrast media. The only complication was a single transient occipital visual field loss. LIMA caliber too narrow to permit use as a graft was found twice, LIMA occlusion unrelated to prior surgery was found once, and LIMA occlusion related to prior surgery was found twice. Subclavian and/or vertebral stenosis was present five times. Large proximal branches of the LIMA best identified prior to surgery were present 12 times. Based on this experience, LIMA angiography 1) can be performed safely with a high degree of success, 2) demonstrates significant findings in 15% of cases, and 3) should therefore be performed whenever coronary angiographic findings make it appropriate to consider LIMA to coronary artery bypass grafting.

The effects of labetalol and prazosin on exercise haemodynamics in hypertensive patients

The antihypertensive and haemodynamic effects of labetalol were compared with those of prazosin both at rest and during bicycle exercise in 38 moderate to moderately severe hypertensive patients (supine DBP 95 to 119 mmHg when untreated). Following a two week open placebo phase to establish baseline BP and baseline exercise performance, patients were randomly and double-blindedly assigned to receive labetalol or prazosin. Drug dose was titrated from 100 to 400 mg labetalol twice daily, or from one to 10 mg prazosin twice daily at weekly intervals until BP was controlled (supine DBP less than or equal to 90 mmHg with at least a 10 mmHg decrease from baseline). Eighteen labetalol and twenty prazosin patients achieved BP control and were subsequently reexercised to fatigue on a bicycle ergometer. The mean changes from baseline for heart rate and rate pressure product (heart rate x SBP) were reduced only in the labetalol group; the difference between the labetalol and prazosin groups was significant (P less than 0.01) both at rest and during exercise. This haemodynamic profile of labetalol may be important in selecting a vasodilating antihypertensive for patients with concomitant ischaemic heart disease.

Complete heart block complicating retrograde left heart catheterization

Three cases of complete heart block complicating retrograde left heart catheterization are presented. In two of the three cases, electrophysiologic study documented block below the AV (atrial ventricular) node. In the third recurrent complete heart block was fatal. It appears that complete heart block complicating retrograde left sided cardiac catheterization is not simply a pericatheterization event; rather, it appears that there is high risk of recurrent complete heart block and that electrophysiologic study is mandatory.

Pigtail-guidewire technique for retrograde crossings of stenotic aortic valve--a case report

A new technique for retrograde crossing of stenotic aortic valves using the pigtail catheter and a straight guidewire is described.

Bilateral coronary thrombosis in the absence of inducible coronary spasm, thrombocytosis, coagulation abnormalities, or angiographic evidence of coronary artery disease: previously undescribed method of myocardial infarction

A 32-year-old man presented with symptoms and electrocardiographic changes consistent with acute anterolateral myocardial infarction. Selective coronary angiography revealed thromboses in the infarct related artery as well as in the right coronary artery. This case is unique because bilateral in-situ coronary thrombosis producing acute myocardial infarction was documented in the absence of previously proposed mechanisms.

Effect of labetalol on exercise tolerance and double product in mild to moderate essential hypertension

Maximal exercise capacity after control of resting blood pressure with labetalol was studied in nine hypertensive men aged 34 to 69 years (average 52 years). Subjects exercised to exhaustion on an upright cycle ergometer with workload increased as a step function by 25 watts every three minutes, both before and after control of blood pressure was obtained. Mean exercise capacity expressed as total time of exercise until exhaustion was 936 seconds prior to control of the resting blood pressure and 884 seconds (no significant difference) after control of resting blood pressure with labetalol. Double product at peak exercise fell from 254 X 10(2) mm Hg beats per minute prior to blood pressure control to 183 X 10(2) mm Hg beats per minute (p = 0.006) after control of blood pressure with labetalol. The difference in the means of resting heart rate and both peak blood pressure and peak heart rate with exercise were all statistically significant after control of blood pressure with labetalol. These findings suggest that labetalol has an ideal exercise profile affording a cardioprotective effect by decreasing double product but without sacrificing exercise capacity.

Changed learning curve for percutaneous transluminal coronary angioplasty. Implication for the future treatment of coronary artery disease

As with all skilled techniques, there is a learning curve for percutaneous coronary angioplasty. This curve has been well described in the literature and it is generally quoted that an initial success rate of 70 to 75 percent in reaching and crossing lesions is to be expected during the first 20 cases. However, the introduction of the steerable or guidewire-directed dilation catheter has altered the learning curve. After an initial experience of six nonsteerable percutaneous transluminal coronary angioplasty procedures, 20 consecutive steerable percutaneous transluminal coronary angioplasty procedures were performed without a single failure to reach or cross a lesion. These 20 consecutive steerable coronary angioplasty procedures included eight single left anterior descending lesions, two double (lesions located in series) left anterior descending lesions, six single right coronary lesions, one double (lesions located in series) right coronary lesion, and three single circumflex lesions. It is concluded that the introduction of the steerable system for percutaneous transluminal coronary angioplasty has shifted the learning curve, and that skilled and experienced coronary angiographers beginning a coronary angioplasty program can expect an initial success rate in reaching and crossing obstructive coronary lesions far in excess of the figures quoted in the literature. This may have significant implication for the ultimate availability of percutaneous transluminal coronary angioplasty to patients with coronary artery disease.

The radiographic appearance of arterial sheath kinking

A case of arterial sheath kinking is reported. Radiographically, sheath kinking has some features which mimic sheath fracture. The radiographic appearance of sheath kinking is, however, distinctive and clearly separable from sheath fracture, the hallmark of which is extravasation of contrast at the fracture site.

Nonrandom occurrence of single-vessel coronary artery disease

The location of obstructive coronary artery lesions in single-vessel disease is nonrandom. The circumflex coronary artery is protected relative to the right coronary artery. This may have important implications regarding the causation of coronary obstructive lesions.

Recurrent pulmonary embolization following implantation of transvenous pacemaker

A 44-year-old man developed recurrent pulmonary embolization after implantation of a permanent transvenous DVI pacemaker connected to polyurethane leads. Thrombus was found in the left innominate and subclavian veins around the pacemaker leads, but not in the right atrium or in the venous system of the pelvis and the lower extremities. The recurrence of pulmonary embolization followed discontinuation of treatment with Coumadin. This case demonstrates that lifelong anticoagulation is indicated in patients who have had pulmonary embolization and/or venous thrombosis around the pacemaker leads.

Coronary artery dissection secondary to coronary arteriography: case report and review

A case of catheter-induced proximal dissection of an angiographically normal left coronary artery is reported. Dissection was not associated with pressure damping and myocardial ischemia was delayed until 1 hour after dissection occurred. Prompt recognition of this entity is essential as emergency revascularization is the treatment of choice when significant amounts of myocardium are threatened.

Catheter separation during coronary angiography

Complete fracture and separation of a right coronary Judkins catheter during coronary angiography is presented. The possible mechanism underlying the separation and retrieval of the catheter fragment is described.