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Background Limited research has been conducted on the surgical management of the aortic valve in congenitally corrected transposition of great arteries (ccTGA) and to our knowledge there have been no reports on the treatment of bicuspid aortic regurgitation (AR) in ccTGA. We report on a ccTGA patient with bicuspid AR and systemic right ventricule (SRV) dysfunction who underwent transcatheter aortic valve replacement (TAVR). Case summary A 17-year-old male with a history of ccTGA and cerebral palsy diagnosed at birth presented with heart failure. During childhood, he did not experience any heart failure symptoms, however, secondary to progressive bicuspid AR he experienced worsening SRV dysfunction beginning at 15-year-old. Echocardiography showed reduced SRV ejection fraction and severe bicuspid AR. The heart team, including a cardiac surgeon and paediatric cardiologist, discussed the treatment strategies and decided to proceed with TAVR as surgical aortic valve replacement was deemed high risk. TAVR was performed with the 34 mm Evolut R (Medtronic, Minneapolis, MN, USA). Post-operative echocardiography showed severe paravalvular leak (PVL). Therefore, valve-in-valve TAVR using a 29 mm Edwards SAPIEN 3 (Edwards Lifesciences, Irvine, CA, USA) was performed on post-operative Day 2 for PVL reduction. Following second procedure, PVL was significantly improved. The patient was discharged in stable condition. Discussion This is the first case wherein TAVR was performed for bicuspid AR in a patient with ccTGA. With appropriate preparation and planning and a collaborative multi-disciplinary team approach, TAVR can be a treatment option for severe AR in patients with ccTGA at high risk for surgery.

Background Ventricular‐arterial coupling predicts outcomes in patients with heart failure. The arterial elastance to end‐systolic elastance ratio (Ea/Ees) is a noninvasively assessed index that reflects ventricular‐arterial coupling. We aimed to determine the prognostic value of ventricular‐arterial coupling assessed through Ea/Ees after transcatheter aortic valve replacement to predict clinical events. Methods and Results We retrieved data on 1378 patients (70% women) who underwent transcatheter aortic valve replacement between October 2013 and May 2017 from the OCEAN‐TAVI (Optimized transCathEter vAlvular iNtervention) Japanese multicenter registry. We determined the association between Ea/Ees and the composite end point of hospitalization for heart failure and cardiovascular death by classifying the patients into quartiles based on Ea/Ees values (group 1: 0.666) during the midterm follow‐up after transcatheter aortic valve replacement. During a median follow‐up period of 736 days (interquartile range, 414–956), there were 247 (17.9%) all‐cause deaths, 89 (6.5%) cardiovascular deaths, 130 (9.4%) hospitalizations for heart failure, and 199 (14.4%) composite events of hospitalization for heart failure and cardiovascular death. The incidence of the composite end point was significantly higher in group 2 (hazard ratio [HR], 1.76; 95% CI, 1.08–2.87 [ P =0.024]), group 3 (HR, 2.43; 95% CI, 1.53–3.86 [ P P P =0.015]). Conclusions These findings suggest that a higher Ea/Ees at discharge after transcatheter aortic valve replacement is associated with adverse clinical outcomes during midterm follow‐up. Registration URL: https://www.upload.umin.ac.jp/ . Unique identifier: UMIN000020423.

Ascending aortic dilatation occurs frequently in patients with aortic stenosis (AS) [(1)][1]. In our study, we sought to investigate the prevalence, characteristics, and clinical impact of ascending aortic dilatation in patients undergoing transcatheter aortic valve replacement (TAVR) for tricuspid

Objectives The authors sought to investigate the prevalence, risk factors, and mid-term mortality in Asian patients with prosthesis–patient mismatch (PPM) after transcatheter aortic valve replacement (TAVR). Background Little information is available on PPM after TAVR in Asian patients. Methods The authors included 1,558 patients enrolled in the OCEAN-TAVI (Optimized transCathEter vAlvular iNtervention) Japanese multicenter registry from October 2013 to July 2016 after excluding patients who died following TAVR before discharge. PPM was defined as moderate if ≧0.65 but ≦0.85 cm2/m2, or severe if Results Of the 1,546 patients, moderate and severe PPM were observed in 138 (8.9%) and 11 (0.7%) patients, respectively. These 149 patients were included in the PPM group. The median age and body surface area were 85 years (interquartile range [IQR]: 81 to 88 years) and 1.41 m2 (IQR: 1.30 to 1.53 m2), respectively. In our multivariate analysis, younger age, larger body surface area, smaller aortic valve area, smaller annulus area, no balloon post-dilatation, and use of Edwards Sapien 3 (Edwards Lifesciences, Irvine, California) were identified as independent predictors of PPM. The estimated cumulative all-cause mortality at 1 year using the Kaplan-Meier method was similar between the PPM and non-PPM groups (10.2% vs. 8.3%; log-rank; p = 0.41). Conclusions The low prevalence of PPM and mortality at 1 year in patients with PPM after TAVR in this Japanese cohort implies that PPM is not a risk factor for mid-term mortality in Asian patients who have undergone TAVR.

Aims Self–expanding (SE) valves are characterized with long stent frame design and the radial force of the device exists both in the inflow and outflow level. Therefore, we hypothesized that device success of SE-valves may be influenced by ascending aortic dimensions (AAD). The aim of this study was to determine the influence of AAD on acute device success rates following SE transcatheter aortic valve replacement (TAVR). Methods & Results In 4 centers in the United States and Asia, 214 consecutive patients underwent SE-TAVR. Outcomes were assessed in line with Valve Academic Research Consortium criteria. AAD was defined as the sum of the short and long axis aortic diameter divided by 2. Overall, device success rate was 85.0%. Multivariate analysis revealed that increased AAD (Odds ratio 1.27) and % oversizing (Odds ratio 0.88) were found to be independent predictors of unsuccessful device implantation. The c-statistic of the model for device success was area under the curve 0.79, sensitivity 81.3% and specificity 44.0%. Co-existence of several risk factors was associated with an exponential fall to 64.2% in device success rate. For a large AAD, however, optimally oversized SE-valves (threshold 16.2%) resulted with high device success rates compared to suboptimal oversizing (88.6% vs. 64.2%, p=0.005). Conclusions Larger AAD and smaller degrees of oversizing were confirmed to be the most relevant predictors of unsuccessful device implantation following SE-valve implantations. Optimal oversizing of great significance was noted, particularly that with a large AAD.

Background: The purpose of this study was to evaluate the outcomes of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (AS). Methods: From April 2012 and December 2016, 108 patients with bicuspid AS underwent TAVR using the Sapien XT (34 patients) and Sapien 3 (74 patients) valves. Procedural and clinical outcomes were assessed according to VARC-2 criteria and compared between the two devices. Results: In the overall cohort, the majority of patients were male (71.3%) with an intermediate surgical risk and a mean Society of Thoracic Surgeons (STS) score of 5.2%. Compared to the Sapien XT group, the Sapien 3 group had a significantly lower STS score (3.3%±2.0% vs. 6.7%±3.6%; P=0.001). Compared to the Sapien XT group, the Sapien 3 group had a significantly lower rate of moderate or severe paravalvular leak (2.7% vs. 14.7%; P=0.03) and higher device success (97.3% vs. 82.4%; P=0.006). There were no significant differences between the two groups in terms of 30-day all-cause mortality, stroke, life-threatening bleeding, major vascular complication and acute kidney injury (stage 2 or 3). Cumulative all-cause mortality at 1-year follow-up was 6.9%. There were no significant differences in cumulative event rates for all-cause mortality at 1-year follow-up between the two groups (9.4% vs. 4.6%; log-rank P=0.47). By univariate analysis, major vascular complication was significantly associated with overall all-cause mortality [hazard ratios (HR): 7.57; 95% confidence interval (CI): 1.51–37.86; P=0.014]. Conclusions: TAVR using the balloon-expandable valves provided acceptable procedural and clinical outcomes in patients with bicuspid AS. The new-generation Sapien 3 valves showed improved procedural outcomes compared to the early-generation Sapien XT valves.

The aim of this study was to investigate the incidence, characteristics, hemodynamic conditions, and clinical significance of right-to-left (R-L) shunt through an iatrogenic atrial septal defect (iASD) after the MitraClip procedure.R-L shunt through an iASD after the MitraClip procedure has not been well investigated.From 2014 to 2017, 385 consecutive patients with mitral regurgitation underwent the MitraClip procedure. iASD was assessed using intraprocedural transesophageal echocardiography. Right and left heart catheterization was used to assess the hemodynamic status of patients. All patients provided written informed consent for the procedure. All data for this study were collected from an established interventional cardiology laboratory database approved by the Cedars-Sinai Medical Center Institutional Review Board.R-L shunt was observed in 20 patients (5%). In 7 of these patients (35%), R-L shunt was accompanied by acute deoxygenation. Prevalence of severe tricuspid regurgitation (55% vs. 20%; p = 0.001), serum B-type natriuretic peptide (664 pg/ml [434 to 1,169 pg/ml] vs. 400 pg/ml [195 to 699 pg/ml]; p = 0.006), mean pulmonary artery pressure (38 mm Hg [34 to 45 mm Hg] vs. 29 mm Hg [22 to 37 mm Hg]; p 0.001), and right atrial pressure (19 mm Hg [13 to 20 mm Hg] vs. 10 mm Hg [7 to 14 mm Hg]; p 0.001) were significantly higher in patients with R-L shunt than in those with left-to-right shunt. Patients with R-L shunt also showed a more prominent reduction in the left atrial V-wave and mean pressure from baseline to post-procedure compared with those with left-to-right shunt (-22.8 ± 2.6 mm Hg vs. -11.8 ± 0.9 mm Hg [p = 0.002] and -7.9 ± 0.8 mm Hg vs. -4.0 ± 0.4 mm Hg [p = 0.003], respectively).R-L shunt through an iASD was observed in 5% of patients who underwent the MitraClip procedure and in one-third of patients with R-L shunt presented acute deoxygenation. Elevated right atrial pressure concomitant with pulmonary hypertension and significant reduction in left atrial pressure after MitraClip deployment were associated with R-L shunt.

Objectives The aim of this study was to report the 1-year results of transcatheter aortic valve replacement (TAVR) with the Edwards SAPIEN 3 (S3) valve in extremely large annuli. Background Favorable 30-day outcomes of S3 TAVR in annuli >683 mm2 have previously been reported. Pacemaker implantation rates were acceptable, and a larger left ventricular outflow tract and more eccentric annular anatomy were associated with increasing paravalvular leak. Methods From December 2013 to December 2018, 105 patients across 15 centers with mean area 721.3 ± 36.1 mm2 (range: 683.5 to 852.0 mm2) underwent TAVR using an S3 device. Clinical, anatomic, and procedural characteristics were analyzed. One-year survival and echocardiographic follow-up were reached in 94.3% and 82.1% of patients, respectively. Valve Academic Research Consortium-2 30-day and 1-year outcomes were reported. Results The mean age was 76.9 ± 10.4 years, and Society of Thoracic Surgeons predicted risk score averaged 5.2 ± 3.4%. One-year overall mortality and stroke rates were 18.2% and 2.4%, respectively. Quality-of-life index improved from baseline to 30 days and at 1 year (p Conclusions S3 TAVR in annular areas >683 mm2 is feasible, with favorable mid-term outcomes.

BACKGROUND Patients with severe aortic stenosis (AS) and an extra-large annulus (ELA) area (>683 mm2) can rarely be treated by transcatheter aortic valve replacement (TAVR) because of the size limitation of the transcatheter heart valves. This study aimed to evaluate the feasibility of TAVR using a 29-mm SAPIEN3 (S3) valve in patients with ELA and S3-dimensions by post-procedural computed tomography (post-CT). Methods and Results: We included 261 patients undergoing TAVR using a 29-mm S3: 30 patients with ELA and 231 with non-ELA were identified. S3-dimensions were evaluated at the S3 inflow and annulus level by post-CT in 129 patients. The ELA group had a greater aortic annulus area measured by pre-procedural CT (737.3±54.7 vs. 578.4±41.9 mm2, P

ObjectivesPatients’ backgrounds and clinical outcomes in urgent/emergent/salvage transcatheter aortic valve replacement (Em-TAVR) remain unclear. We investigated patient characteristics and the mortality in Em-TAVR and the predictors for the need for Em-TAVR.MethodsWe consecutively enrolled 1613 patients undergoing TAVR for severe aortic stenosis between October 2013 and July 2016 from the Optimised transCathEter vAlvular interventioN (OCEAN)-transcatheter aortic valve implantation (TAVI) registry. The urgency was based on the European System for Cardiac Operative Risk Evaluation II. Urgent, emergent or salvage were included with the Em-TAVR group and elective with the El-TAVR group.ResultsEm-TAVR was observed in 87 (5.4%) patients. A higher Clinical Frailty Scale (CFS), peripheral artery disease (PAD), hypoalbuminaemia, reduced left ventricular ejection fraction (LVEF) and preoperative at least moderate mitral regurgitation (MR) predicted the need for the Em-TAVR by the multivariate logistic regression analysis. The Em-TAVR group had the higher Society of Thoracic Surgeons Score (13.7 (IQR 8.2–21.0) vs 6.5 (IQR 4.6–9.2); pConclusionsEm-TAVR was performed in 5.4% of patients. Higher CFS, PAD, hypoalbuminaemia, reduced LVEF and preprocedural MR predicted the need for Em-TAVR. Em-TAVR was not a predictor for mortality in the multivariate analysis, suggesting that it is a reasonable treatment option.

Stroke during transcatheter aortic valve replacement (TAVR) for aortic stenosis (AS) remains a concerning complication, and its mechanism is still unclear [(1)][1]. Histopathological analyses of debris captured by a cerebral protection during TAVR showed that the debris consisted of diverse material

Coronary obstruction is a rare (

As transcatheter aortic valve replacement (TAVR) expands to lower-risk patients, the longer-term impact of paravalvular leak (PVL) may become relevant. The aim of this study was to determine the influence of mild PVL in patients with pre-procedural no aortic regurgitation (AR) on two-year

Bicuspid aortic valve is the most common congenital cardiac malformation. Aortic valve replacement is often required in older patients but the surgical risk is often extremely high. As Transcatheter aortic valve implantation (TAVI) is an established therapy for intermediate and high surgical risk patients with symptomatic severe aortic valve stenosis (AS). Advances in technology and knowledge have led to TAVI being used for other pathologies and populations such as bicuspid AS. Recently, the diagnosis and classification of bicuspid aortic valve based on multidetector computed tomography (MDCT) assessment has been proposed, which may have an impact of outcomes after TAVI. This review article describes the advancements in diagnosis and outcomes of bicuspid AS.

Aortic root rupture is a rare, but potentially fatal, complication of transcatheter aortic valve replacement (TAVR).1,2 Despite the advances in TAVR technology, aortic root rupture continues to be associated with high mortality because of the lack of effective treatment options for this complication. We describe 2 cases of aortic root rupture occurring during TAVR that were managed percutaneously with coil embolization of the periaortic space created by the root rupture. A 79-year-old patient underwent TAVR with a 29-mm Evolut R (Medtronic, Inc, Minneapolis, MN). Pre-TAVR computed tomography revealed annular perimeter 81.6 mm (mean diameter, 26.0 mm). Because of significant paravalvular aortic regurgitation (Figure 1A; Movie IA in the Data Supplement), post-dilation was performed with a 26 mm×4.5 cm True Balloon (Figure 1B; Movie IB in the Data Supplement). Immediately after post-dilation, a large pericardial effusion was noted (Figure 1C; Movie IC in the Data Supplement). Emergent pericardiocentesis was performed. Selective injection into the left coronary cusp with a 6F XB-LAD 3.5 guide catheter revealed the site of aortic root rupture in the left coronary sinus, with contrast extravasating into the pericardial space (Figure 1D and 1E; Movie ID …

Bicuspid aortic valve is the most common congenital cardiac defect in adults, and symptom typically develops in adulthood. In the majority of cases, bicuspid aortic valve disease progress with ages and surgical aortic valve replacement is performed with excellent operative outcomes. However, with the relatively slow progression of disease, surgical aortic valve replacement is required in elderly patients but the surgical risk often deemed extremely high due to old age and multiple comorbidities. Transcatheter aortic valve replacement (TAVR) has evolved from a novel technology to an established therapy for intermediate- and high-risk patients with symptomatic severe aortic valve stenosis (AS). Numerous studies have demonstrated the safety and efficacy of TAVR, and more than 250,000 patients have been treated with this technology. Although randomized trials have established TAVR as the standard treatment, these trials excluded congenital bicuspid AS due to its unique morphological features. Nevertheless, the growing experience, accumulated knowledge, and advancements of new technology lead to the expand use of TAVR to other pathologies or other populations such as bicuspid AS. With integration of imaging multimodalities (computed tomography and echocardiography), the diagnosis and classification of bicuspid aortic valve has been changing. Due to unfavorable anatomic features of bicuspid AS, the outcomes of TAVR in bicuspid AS was suboptimal, particularly when using the first-generation transcatheter valves. However, the newer-generation transcatheter valves significantly improved the outcomes of TAVR in bicuspid AS. Nonetheless, several issues still remain to be resolved. Given longer life expectancy in patients with bicuspid AS undergoing TAVR, durability of transcatheter valves is concerned. In addition, patients with bicuspid aortic valves often have concomitant dilatation of proximal part of ascending aorta (aortopathy), but limited data exist about the clinical prognosis of bicuspid aortic valve with concomitant aortopathy in elderly patients. Considering the expanding indication of TAVR to lower surgical risk and younger population, these issues should be evaluated in future studies.

An 81-year-old woman underwent transcatheter aortic valve replacement (TAVR) for aortic stenosis. Pre-procedural computed tomography revealed an aortic annulus perimeter of 68.5 mm. The mean diameter of the sinus of Valsalva was 27.3 mm. An Evolut R 26-mm device (Medtronic, Minneapolis, Minnesota

Objectives The aim of this study was to assess the safety and efficacy of sheathless guide catheters in transradial percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). Background Transradial PCI for STEMI offers significant clinical benefits, including a reduced incidence of vascular complications. As the size of the radial artery is small, the radial artery is frequently damaged in this procedure using large-bore catheters. A sheathless guide catheter offers a solution to this problem as it does not require an introducer sheath. However, the efficacy and safety of sheathless guide catheters remain to be fully determined in emergent transradial PCI for STEMI. Methods Data on consecutive STEMI patients undergoing primary PCI at the Sendai Kousei Hospital between September 2010 and May 2013 were analyzed. The primary endpoint was the rate of acute procedural success without access site crossover. Secondary endpoints included door-to-balloon time, fluoroscopy time, volume of contrast, and radial artery stenosis or occlusion rate. Results We conducted transradial PCI for 478 patients with STEMI using a sheathless guide catheter. Acute procedural success was achieved in 466 patients (97.5%). The median door-to-balloon time was 45 min (range, 15–317 min). The median fluoroscopy time was 16.4 min (range, 10–90 min). The median volume of contrast was 134 mL (range, 31–431 mL). Radial stenosis or occlusion developed in 14 (3.8%) of the 370 evaluable patients. Conclusions This study showed that use of a sheathless guide catheter taking a transradial approach was effective and safe in primary PCI for STEMI. © 2015 Wiley Periodicals, Inc.

BACKGROUND The aim of this study was to determine the influence of an elliptic annulus on acute device success rates following self-expanding (SE) transcatheter aortic valve replacement (TAVR) vs. balloon-expandable (BE) TAVR.Methods and Results:Outcomes were assessed using Valve Academic Research Consortium-2 definitions. Aortic annulus ratio (AAR) was measured as short axis diameter/long axis diameter. Mean AAR was 0.81±0.06. Patients were therefore divided into 2 groups: AAR

Aims The impact of left ventricular outflow tract calcification (LVOT-CA) on SAPIEN 3 transcatheter aortic valve replacement (S3-TAVR) is not well understood. The aims of the present study were to determine optimal device sizing for S3-TAVR in patients with or without LVOT-CA and to evaluate the influence of residual paravalvular leak (PVL) on survival after S3-TAVR in these patients. Methods and results This study analysed 280 patients (LVOT-CA=144, no LVOT-CA=136) undergoing S3-TAVR. Optimal annular area sizing was defined as % annular area sizing related to lower rates of ≥mild PVL. Annular area sizing was determined as follows: (prosthesis area/CT annulus area-1)×100. Overall, ≥mild PVL was present in 25.7%. Receiver operating characteristic curve analysis for prediction of ≥mild PVL in patients with LVOT-CA showed that 7.2% annular area sizing was identified as the optimal threshold (area under the curve [AUC] 0.71). Conversely, annular area sizing for no LVOT-CA appeared unrelated to PVL (AUC 0.58). Aortic annular injury was seen in four patients (average 15.5% annular area oversizing), three of whom had LVOT-CA. Although there was no difference in one-year survival between patients with ≥mild PVL and without PVL (log-rank p=0.91), subgroup analysis demonstrated that patients with ≥moderate LVOT-CA who had ≥mild PVL had lower survival compared to patients with ≥mild PVL and none or mild LVOT-CA (log-rank p=0.010). Conclusions In the setting of LVOT-CA, an optimally sized S3 valve is required to reduce PVL and to increase survival following TAVR.

Coronary obstruction is a rare (

Given previously reported favorable short-term outcomes, we report 1-year results of Sapien3(S3) TAVR in extremely large annuli beyond manufacturer recommended range(area >683mm2) From 12/2013-8/2018, 97 patients across 13 centers with mean area 722.6+/-37.2mm2 (range: 683.5 to 852.0) underwent S3

Background: The semiquantitative Clinical Frailty Scale (CFS) is a simple tool to assess patients’ frailty and has been shown to correlate with mortality in elderly patients even when evaluated by nongeriatricians. The aim of the current study was to determine the prognostic value of CFS in patients who underwent transcatheter aortic valve replacement. Methods: We utilized the OCEAN (Optimized Catheter Valvular Intervention) Japanese multicenter registry to review data of 1215 patients who underwent transcatheter aortic valve replacement. Patients were categorized into 5 groups based on the CFS stages: CFS 1-3, CFS 4, CFS 5, CFS 6, and CFS ≥7. We subsequently evaluated the relationship between CFS grading and other indicators of frailty, including body mass index, serum albumin, gait speed, and mean hand grip. We also assessed differences in baseline characteristics, procedural outcomes, and early and midterm mortality among the 5 groups. Results: Patient distribution into the 5 CFS groups was as follows: 38.0% (CFS 1-3), 32.9% (CFS4), 15.1% (CFS 5), 10.0% (CFS 6), and 4.0% (CFS ≥7). The CFS grade showed significant correlation with body mass index (Spearman’s ρ=−0.077, P =0.007), albumin (ρ=−0.22, P P P P P Conclusions: In addition to reflecting the degree of frailty, the CFS was a useful marker for predicting late mortality in an elderly transcatheter aortic valve replacement cohort.

A 78-year-old woman with severe aortic stenosis underwent transcatheter aortic valve implantation (TAVI) with a balloon expandable bioprosthesis: a 23-mm Sapien XT valve (Edwards Life Sciences, Inc., CA, USA). A set of the valve and a balloon (NovaFlex, Edwards Transfemoral Balloon Catheter, Edwards Life Sciences, Inc., CA, USA) was successfully delivered to an optimal position using a 16-French expandable introducer hydrophilic sheath. Inflation of the balloon was commenced, and expansion was initially smooth. However, it ruptured immediately before completion of expansion, resulting in a rapid deterioration in hemodynamics. Even though no migration of the stent valve was observed, transesophageal echocardiography and aortography revealed massive paravalvular aortic regurgitation (AR), suggesting that AR was attributable to insufficient expansion. After post -dilatation of the stent valve using a 23- mm balloon (Edwards Transfemoral Balloon Catheter, Edwards Life Sciences, Inc., CA, USA), the patient’s condition began to improve, and further aortography indicated an improvement in paravalvular AR. This case represented that balloon rupture could led to sudden onset massive paravalvular AR. Interventional cardiologists should recognize it as a significant complication in patients undergoing TAVI using a balloon-expandable bioprosthesis, with the possibility of severe cardiogenic shock.

Little is known about outcome of transcatheter aortic valve replacement (TAVR) using Sapien 3 (S3) (Edwards Lifescience, Irvine, CA) in patients with aortic annulus area of more than 683 mm2. The aim of this study is to investigate procedural outcomes and short-term mortality in patients with aortic

Background: Bicuspid aortic valve (BAV) is regarded as a risk of uneven expansion and subsequent dysfunction of the transcatheter heart valve (THV). This study is to evaluate the valve geometry of Sapien 3 THV used with BAV patient in transcatheter aortic valve implantation (TAVI). Methods: We

Introduction Little information is available on the pathogenesis of heatstroke without strenuous exercise in younger patients. Here, we report the case of a 31-year-old man who developed heatstroke secondary to hyponatremia. His condition was initially misdiagnosed as classic heatstroke. We hope the detailed description of our patient’s case will provide valuable information for medical professionals faced with similar cases in the future. Case presentation A 31-year-old Japanese man who was regularly taking anti-hypertensive agents, including a thiazide, was admitted to our hospital owing to consciousness disturbance and a high-grade fever. A thorough examination revealed mild renal dysfunction, rhabdomyolysis, a hyper-coagulable state, and severe hyponatremia (114mEq/L). Because he worked in a hot environment, an initial diagnosis of heatstroke was established. His general condition improved rapidly with supportive measures, and he was discharged on the fourth day after admission. Interestingly, he did not recognize feeling hot while working in a hot environment. These findings suggest that the consciousness disturbance, which was probably attributable to acute hyponatremia caused by the thiazide, preceded the onset of the heatstroke. Conclusions Clinicians should consider the presence of underlying diseases, especially consciousness disturbance, when younger individuals develop heatstroke in the absence of strenuous exercise.