Diagnosis of Atrial Fibrillation Using Machine Learning With Wearable Devices After Cardiac Surgery: Algorithm Development Study

Background

Some attempts have been made to detect atrial fibrillation (AF) with a wearable device equipped with photoelectric volumetric pulse wave technology, and it is expected to be applied under real clinical conditions.

Objective

This study is the second part of a 2-phase study aimed at developing a method for immediate detection of paroxysmal AF, using a wearable device with built-in photoplethysmography (PPG). The objective of this study is to develop an algorithm to immediately diagnose AF by an Apple Watch equipped with a PPG sensor that is worn by patients undergoing cardiac surgery and to use machine learning on the pulse data output from the device.

Methods

A total of 80 patients who underwent cardiac surgery at a single institution between June 2020 and March 2021 were monitored for postoperative AF, using a telemetry-monitored electrocardiogram (ECG) and an Apple Watch. AF was diagnosed by qualified physicians from telemetry-monitored ECGs and 12-lead ECGs; a diagnostic algorithm was developed using machine learning on the pulse rate data output from the Apple Watch.

Results

One of the 80 patients was excluded from the analysis due to redness caused by wearing the Apple Watch. Of 79 patients, 27 (34.2%) developed AF, and 199 events of AF including brief AF were observed. Of them, 18 events of AF lasting longer than 1 hour were observed, and cross-correlation analysis showed that pulse rate measured by Apple Watch was strongly correlated (cross-correlation functions [CCF]: 0.6-0.8) with 8 events and very strongly correlated (CCF>0.8) with 3 events. The diagnostic accuracy by machine learning was 0.9416 (sensitivity 0.909 and specificity 0.838 at the point closest to the top left) for the area under the receiver operating characteristic curve.

Conclusions

We were able to safely monitor pulse rate in patients who wore an Apple Watch after cardiac surgery. Although the pulse rate measured by the PPG sensor does not follow the heart rate recorded by telemetry-monitored ECGs in some parts, which may reduce the accuracy of AF diagnosis by machine learning, we have shown the possibility of clinical application of using only the pulse rate collected by the PPG sensor for the early detection of AF.

A Case of Clinically Amyopathic Dermatomyositis that was Refractory to Intensive Immunosuppressive Therapy including Tofacitinib, but Successfully Treated with Plasma Exchange Therapy

Clinically amyopathic dermatomyositis (CADM) patients often develop rapidly progressive interstitial lung disease (RP-ILD). A high level of anti-melanoma differentiation-associated gene 5 antibodies (anti-MDA5 Ab) before treatment is associated with RP-ILD development, a poor treatment response, and poor survival. The prognosis of CADM patients remains poor due to ILD even with combined intensive immunosuppressive therapy. Recently, several additional therapies, including tofacitinib (TOF) and plasma exchange (PE) therapy, have been reported to be effective. We herein report a case of CADM-ILD with a high level of anti-MDA5 Ab that was refractory to combined intensive immunosuppressive therapy including TOF, but successfully treated with PE. The following are possible reasons why TOF was ineffective: 1) cytokines that were not suppressed by TOF played an important role in RP-ILD; 2) TOF was administered later than previously reported; and 3) TOF did not suppress pathological substances such as antibodies. On the other hand, PE removes cytokines and various pathological substances. Therefore, PE may be a more reasonable additional therapy for intractable CADM-ILD.

Giant Cell Arteritis Presenting with Ptosis and Diplopia

Giant cell arteritis (GCA) is vasculitis of large-sized vessels that can lead to vision loss. We herein report a rare case of GCA accompanied by ptosis and diplopia as early symptoms, which were caused by third nerve palsy. A 78-year-old man presented with fever, right temporal headache, right eyelid ptosis, and diplopia. GCA was confirmed by a temporal artery biopsy. The symptoms disappeared after a slight delay following the administration of prednisolone. Unlike vision loss, ptosis and diplopia are considered to be reversible and responsive to treatment. GCA should not be ruled out if patients exhibit these ophthalmic symptoms.

Usefulness of tissue inhibitor of metalloproteinase 1 as a predictor of sustained remission in patients with antineutrophil cytoplasmic antibody-associated vasculitis

Background

We previously identified tissue inhibitor of metalloproteinase 1 (TIMP-1) as a biomarker of disease activity that distinguished mildly or highly active antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) from remission 6 months after the initiation of remission-induction therapy. In the present study, we investigated whether TIMP-1 is clinically useful as a predictor of relapse and sustained remission in AAV patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) during maintenance therapy.

Methods

The relationship between serum TIMP-1 levels and clinical outcomes in AAV patients receiving maintenance therapy was assessed using the follow-up data of a Japanese large-cohort study (the RemIT-JAV-RPGN study) and data collected from AAV patients on maintenance therapy in our hospital (the MAAV-EU study).

Results

In the RemIT-JAV RPGN study, serum levels of TIMP-1 were significantly higher in mildly active AAV patients with MPA and GPA 6 months after the initiation of remission-induction therapy than in patients in remission. Regarding maintenance therapy, elevated levels of TIMP-1 in patients in remission were associated with relapse and/or difficulty reducing the glucocorticoid dosage after 6 to 12 months. In the MAAV-EU study, serum levels of TIMP-1 were elevated in relapsed patients 6 months before relapse, earlier than the increase in serum levels of CRP. Analyses of both studies revealed that approximately 30% of patients in remission with a serum TIMP-1 level ≥ 150 ng/mL relapsed after 6 to 12 months, while the majority of patients with a TIMP-1 level < 150 ng/mL sustained remission for at least 12 months.

Conclusion

We herein demonstrated that TIMP-1 is more useful as a predictive biomarker of sustained remission than as a predictor of relapse in maintenance therapy for AAV. TIMP-1 levels < 150 ng/mL are important for the long-term maintenance of remission and may be an indicator for the tapering or cessation of treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02471-5.

Development of a method to measure DNA methylation levels by using methyl CpG-binding protein and luciferase-fused zinc finger protein

DNA methylation, which is an important epigenetic event for transcriptional regulation, is regarded as a biomarker for cancer. A rapid and sensitive method for measuring DNA methylation levels in target genomic regions may enable early diagnosis of cancer. To detect DNA methylation levels conveniently, we developed a detection system for DNA methylation, designated as methylated DNA precipitation combined luciferase-fused zinc finger assay (MELZA), which uses methyl CpG-binding domain (MBD) and luciferase-fused zinc finger protein. This system comprises the following 3 steps: (1) MBD-based methylated DNA precipitation, (2) PCR amplification of the target genomic region, and (3) detection of the PCR product quantity by using luciferase-fused zinc finger protein. Using this system, we have accurately measured methylation levels of the androgen receptor gene promoter region in LNCaP, PC3, Du145, and whole blood cells. This system does not require bisulfite treatment, and all the steps can be automated. Therefore, it might be useful for measuring DNA methylation levels in clinical cancer diagnoses.

Transesophageal echocardiography (TEE): its diagnostic value in endocarditis

Transthoracic two-dimensional echocardiography (TTE) has been an accepted noninvasive procedure used to diagnose infective endocarditis by demonstrating the presence of vegetations and other complications such as ring abcess, mycotic lesions or sinus of valsalva aneurysm. Moreover, complementary Doppler and Color Flow imaging are very useful in detecting early valvular regurgitation and in evaluating the severity of such regurgitant lesions. Occasionally, TTE fails to provide an adequate quality of imaging because of the patient's obesity, chest deformity or emphysema. Transesophageal echocardiography (TEE) on the other hand, a relatively new technique, allows ultrasonic imaging of the heart through the esophagus and provides a clear visualization of all cardiac structures without any interference from the lungs, chest wall or rib cage. We present a case of aortic valve endocarditis diagnosed by TEE.

Inhibitory and stimulatory effects of glucocorticoid on androgen-induced growth of murine Shionogi carcinoma 115 in vivo and in cell culture

It has been generally accepted for 20 years that the growth of Shionogi carcinoma 115 (SC115) is stimulated only by androgen in vivo and in cell culture. However, we recently found that the growth of SC115 is also stimulated by pharmacological, but not physiological, doses of glucocorticoid both in vivo and in cell culture and by pharmacological doses of estrogen only in vivo. In the present study, therefore, we investigated the effect of dexamethasone on androgen-induced growth of SC115 cells in vivo and in cell culture. In a serum-free medium [Ham's F-12:Eagle's minimum essential medium (1:1, v/v) containing 0.1% bovine serum albumin], the proliferation of SC-3 cells (a cloned cell line from SC115 cells) estimated by cell number and DNA synthesis reached a plateau at 10(-8) M testosterone (up to 93-fold) or 10(-6) M dexamethasone (up to 7.2-fold); high stimulation induced by higher than 10(-8) M testosterone was inhibited by the addition of 10(-5)-10(-8) M dexamethasone in a concentration-dependent manner, whereas low stimulation induced by lower than 10(-10) M testosterone was significantly enhanced by the addition of dexamethasone. The presence of typical glucocorticoid and androgen receptors in SC-3 cells was also demonstrated; dexamethasone did not bind to androgen receptor and testosterone did not bind to glucocorticoid receptor. In castrated mice, the concomitant administration of dexamethasone again significantly inhibited the high growth of SC115 tumors induced by high doses of androgen but significantly enhanced the low growth induced by low doses of androgen. The present results demonstrate both inhibitory and stimulatory effects of glucocorticoid on androgen-induced proliferation of SC115 cells in cell culture and probably in vivo.

Growth-stimulating effect of pharmacological doses of glucocorticoid on androgen-responsive Shionogi carcinoma 115 in vivo in mice and in cell culture

It has been generally accepted for 20 years that the growth of Shionogi carcinoma 115 (SC115) is stimulated only by androgen. However, we recently found that the growth of SC115 cells is also stimulated by pharmacological doses of estrogen in vivo but not in cell culture. In the present study, the growth-stimulatory effect of glucocorticoid on SC115 cells was examined. In castrated mice, daily injections of high doses of dexamethasone (100 micrograms/mouse) markedly stimulated the tumor growth, and the growth approached that found in normal males. However, daily injections of physiological doses of dexamethasone (4 micrograms/mouse) or high doses of epitestosterone, progesterone, or cholesterol (200-5000 micrograms/mouse) did not enhance the tumor growth in castrated mice. The androgen dependency, growth speed, steroid receptors, and histological type of the tumors grown by pharmacological doses of glucocorticoid were not significantly different from those of the original SC115 tumors grown by androgen. In a serum-free medium [Ham's F-12:Eagle's minimum essential medium (1:1, v/v) containing 0.1% bovine serum albumin], the proliferation of SC-3 cells (a cloned cell line from SC115 cells) was markedly (by up to 25-fold) stimulated by 10(-10)-10(-8) M testosterone, whereas the proliferation was only slightly but significantly (by up to 3.3-fold) stimulated by 10(-8)-10(-5) M dexamethasone. The present findings demonstrate that the growth of SC115 cells in vivo and in cell culture is significantly stimulated by physiological doses of androgen or pharmacological doses of glucocorticoid.