{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T16:19:12Z","timestamp":1792253952583,"version":"4.4.0"},"reference-count":31,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,2]],"date-time":"2026-08-02T00:00:00Z","timestamp":1785628800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Environ. Res. Public Health","IJERPH"],"abstract":"<jats:p>Background: Although extreme heat is associated with adverse cardiovascular outcomes, the relationship between heat-alert-threshold days, acute myocardial infarction (AMI) admissions, and post-AMI mortality remains uncertain. We aimed to evaluate the association between temperature-defined heat-alert-threshold days and (i) daily AMI admissions and (ii) cumulative all-cause mortality after hospitalized AMI in Hungary. Methods: We conducted a nationwide registry-based study using data from the Hungarian Myocardial Infarction Registry (HMR). All AMI admissions between 1 January 2018 and 31 December 2019 were eligible, with mortality follow-up through 16 June 2021. Heat-alert-threshold days were defined using the temperature criterion applied in the Hungarian national heat-health action plan (daily mean temperature \u226525 \u00b0C). AMI admissions were analyzed using adjusted quasi-Poisson regression models and cumulative mortality using stratified Cox proportional hazards models. This operational temperature threshold was used as the exposure definition and does not represent linkage to administrative heat-alert declarations. Results: The cohort included 30,883 AMI events from 29,596 unique patients (mean age, 67.2 [SD 12.8] years; 60.3% male). Patients admitted on heat-alert-threshold days had baseline clinical characteristics similar to those admitted on non-alert days (all standardized mean differences &lt;0.10). Heat-alert-threshold days were associated with fewer recorded AMI admissions during summer (adjusted incidence rate ratio [aIRR] 0.93, 95% CI 0.90\u20130.97). In contrast, no association was observed between heat-alert-threshold exposure and subsequent all-cause mortality after AMI hospitalization (adjusted hazard ratio [aHR] 0.96, 95% CI 0.87\u20131.05). These findings remained consistent across sensitivity analyses. Conclusions: In this nationwide Hungarian registry-based study, temperature-defined heat-alert-threshold days were associated with fewer recorded AMI admissions during summer but not with differences in post-AMI mortality among hospitalized patients. The observed inverse association should not be interpreted as evidence of a protective effect of heat exposure. Alternative explanations include behavioral adaptation, delayed care-seeking, exposure misclassification, residual confounding, and the possibility of unmeasured out-of-hospital cardiovascular events, which were not captured by the registry. Because administrative heat-alert declarations were not linked to the analytic dataset, the findings should be interpreted as associations with temperature-defined heat-alert-threshold days rather than evaluations of the effectiveness of the Hungarian heat-alert system.<\/jats:p>","DOI":"10.3390\/ijerph23081010","type":"journal-article","created":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T01:43:27Z","timestamp":1785721407000},"page":"1010","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Temperature-Defined Heat-Alert-Threshold Days and Acute Myocardial Infarction Admissions and Mortality: A Nationwide Hungarian Registry-Based Cohort Study"],"prefix":"10.3390","volume":"23","author":[{"given":"Csaba","family":"B\u00e1lint","sequence":"first","affiliation":[{"name":"Doctoral School of Health Sciences, Faculty of Health Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3079-6233","authenticated-orcid":false,"given":"Ali Abbas Rahi","family":"Al-Murshedi","sequence":"additional","affiliation":[{"name":"Doctoral School of Health Sciences, Faculty of Health Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ammar Mahmood","family":"Jaber","sequence":"additional","affiliation":[{"name":"Doctoral School of Health Sciences, Faculty of Health Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2849-1310","authenticated-orcid":false,"given":"Annam\u00e1ria","family":"Pakai","sequence":"additional","affiliation":[{"name":"Doctoral School of Health Sciences, Faculty of Health Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"},{"name":"Faculty of Health Sciences, Institute of Emergency Care, Pedagogy of Health and Nursing Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5323-0748","authenticated-orcid":false,"given":"Zs\u00f3fia","family":"Verz\u00e1r","sequence":"additional","affiliation":[{"name":"Doctoral School of Health Sciences, Faculty of Health Sciences, University of P\u00e9cs, 7621 P\u00e9cs, Hungary"},{"name":"Medical School, Heart Center, University of P\u00e9cs, 7624 P\u00e9cs, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Yang, L., Zheng, B., and Gong, Y. 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