CINXE.COM

Just a moment...

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "heart.bmj.com",cType: 'managed',cRay: '9141baeb2ef5482e',cH: 'zoRywK304jI4hMqAnJKj3HENLhjt1eGqd6XMSzBaSug-1739920641-1.2.1.1-1Xv4lln.sfFX0ia560g2A2nwZaGFaUcG2KRR7oI6bNd_PyGk.QNS_m4xDZB6BIuj',cUPMDTk: "\/lookup\/doi\/10.1136\/hrt.39.3.233?__cf_chl_tk=.iTgeZN2JqbdSX6bpD.InfeJFjt17OqxceAPcXL3d1M-1739920641-1.0.1.1-0JeAlcpARE5ZzERRmrIvuIffEAK4oDmp6aTGkIYYdbw",cFPWv: 'g',cITimeS: '1739920641',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "unsupported-browser",fa: "\/lookup\/doi\/10.1136\/hrt.39.3.233?__cf_chl_f_tk=.iTgeZN2JqbdSX6bpD.InfeJFjt17OqxceAPcXL3d1M-1739920641-1.0.1.1-0JeAlcpARE5ZzERRmrIvuIffEAK4oDmp6aTGkIYYdbw",md: "kXPG_yX3C.1DOF2tpBkPhdr2IDOPgkCO1uPChxAMROo-1739920641-1.2.1.1-BTUmuHw5RQ6gWQnNcBzewQs4bR1Bg4kGA64d_mGiDSAoIUt.PBZp4PAZhBbX3kS9zFYlhBcYCup59u6m_CqBCzt1BRApTaGljDtY_zcyjJghwtjBa_EjhcySiodRJuXXtZDgXq4ZRmq5W8X2Xd_TiGKNuBzMiGVsI7TVEQe5zRoeTU_e9tH_nQ9eiRIURKaQKqy22ILuxkonizARdjnjJ3vbuDJBX.R.HSv6kT5gUR0iKtzSnVN.VWQWeZI61gzIs2JWiApUFx5EdCEXfYpkBeTVwBCRwqRb3bBiIzLrZZnJQ1miEpsayizEDyfExpoyaw0.ZQpfM38NG.v7y.ODtyEcqFFSU5k6qk3A4FPo2wuZtFBtcGZRpCrM6XVzZs2hemWQmUlaG7yiChNuuWLFTRgTaCqGZjL.4R30freq4nPUOFYjLsxyHPIv3qhrZ3_il8LXzIOh7Cw.ZL.0yK4MvYj0KEMJZoYJVJ8GWK5NGuDZ8PdcBrkb0jrLINE7gRLoYron4fqIhx._bQliwX.7SOlDzA3osWqeUnAqsXvVxfyqtSrTGkyibYoDMDlwieZLfssIsPVWehKr7UbRMyYItgyuGDCnglWgPRuoCKxCZUHs3Koz9RMLbklTAvvx_bYoVeGzkk9cWmZcqh9KlY7s7F6J_rOaoJYKhBMjdowEnfTNSRXNLmQWC7.xf4YbX8yBORk1T7d.okslK2dRj0oEIDzz6G6hqmb1pE6ofmV1L8w.G2osQ4L5q9vqp.r5587wd4CaD4IGH7SkFmknBuNe45fdqsecupNb0XU4LF30SGRuJJs4SdFVY8VuPO8RXSI1CUW4OjgmBLdsSFcOSV7DyXB38vO5vRvJ3eij9VdTbKd7cp0_zYaBNjXXBH76.DqGB5ZOzjP5xVEEEEf5jll1bZ0MR1bPzi4pF4.jHvYRls8Y.8gHFFsxQgZWmWbX0bX8wZ_tjRXHo5Dc_84p27E89ciHmwEgXVeZx1Fmf70oZDUbPIz2culgKkvMWVAu_BmjaUDrWqzC_uaEpY2L_U3yASRXpkykn.iyaaMnlh2zIjLUdtZflbpTWCnW5Jrmi0XsIcN.eO93BFJGb7tPYQgEhco2MXOkSc_6.sUohAodh1XsP8uic69TLTEvMGmlggfkESY4jQJBUMB_6WMp6B_ta1Rm0XAzzdXynT.T4BqHYn1UBo.iJnPKvtyF0mUCY5wpmfI7Wqlpq3nx79btUDvbB9lu5cAByL6p7mJmCqxt9L80obtR473_buD3oMVlkRBQJR.dRYJd2D8rWk1uiOSzKDSauG03BoIsNTl9w3suqYaO2ZDMsEP31m2tTEtZjf_4HYRQ8kBRFN._y4bE0xL4DUi3C0mMpj844R_gNydA82N62VlA7SDn6ufQ0tLpsQD69huOUnh9HRAXK3EP5MC0NOlDuqC6OdKCVbwI5yQnY9Rr3s29HSwBmpQI7gf.Y0ml2i8YAYJ5_szaYu_jjw5GMaAS2JUNZXqob5HEozM8D6REWZEkD4cIWqgS.mo4mpcv.Wz1xD2SJ1NiiGb1zqc9po9bV05JcejLffpfTJesJujI9Oy1DvnbG2wx0_J0uFN9d5fHb.vxsXWTSvPGD0wNwMVf8FZkC2Q1CGyK0kIrf8hMwiAieGxbNBAqtKHI9NQKo.QllW207KHOCDipy4JHyQErRuKscjF7Cq3jw9LviJdV56M8cX__wAt6hTOrpeerrvT_bO70m0t0YuqDfO.IoB.15OQR_QsHnW9BlxISMGM98hKR.CFgfeL.yPDVDe5c23vHw4YnXYFIk9MQILnzPaqyUFRey.GvHNhpIxzXWmqEMCoKCxbsFzJmHdjutH3ZoZNocwc_4pyPZPjptQo4lbWRpsj7SzYzAxqAGpntIZgv_XyefWdheVev0ti2EuXY2xDQc7YOPovAOokg27R5hBiGdN3zOR8YUWD.ZelVwFyMj8ZjunFdY45IkKF1MOxy_SF.4_CwouzonOpv13rmKyIj9qrgnkcL1xg7QEKTDDfEaSk3oGP1kaXTeXZqcXk1LGpBSf1p78bmuQ52X1z0HdnhNJ0i_TQO.w3UuDONXnHn6H3wgwHoYEa2GbAwcRMnLVoy8t2Tp9EixJL2hN4OFuri_luiIt0gNcLBRyM.3LMyorkY2rHKe2tqMWGQ7j8fYu.xdDeHiKvjsgK7KlwNOe0iFnPJ.yEo3QG0SCAy5SwtWINXfTw.bduO9EIA0WrDo90dgcH55iRaz7Q0Lk2.qtmB59RfI7D5nUeMK.qb6nAgQg.CXyGv3ZQl8Zwz98PRkNnLsGjt.eI02jYtiL6GlfZZNGXEjCKX6..q41DAKrbMsz2OQWiA.FbWYpWWsvyXwxBKkqTaMWVnayLrOYl.Jxe9nz0FFE9X7HOzNCb5S3XdI2K4ToknhvYEQerM3i_BejICk1B0e29NVC.2RYkWmaPB5KMY0l4oehCDrA7hXs8hQO1N4O15MU1_zPmEa7eL4oGioaOjNqJphSvq7rnaWX0dN1NQe8iaVu2.HPK1jdzwsfSbomeaZB4uMqZONdP3",mdrd: "eVhjHZNMtlyaakOMzrvsFrac1Pvgx92lBB2aQh_a.qc-1739920641-1.2.1.1-GgDnonUBbETAKbEc2vn18Cfj8OQxxVtUkDqPx8b6A4cuH_98B_aJvfzdJ7QamFAQCglOLgX8m35GQb1QaIZCV8Vd.xypQurYpn7260ehJSTSIRkDPSKlaLOYqKZBmZYDd7nV0FpNXyj4DzSGAbSCxbY.JMmIIfgepabKILB0ig.Rv_wO1dJGyX7CoTnMKPJWEdAlpGB_vl48qb6qZmR32CJLzio6MaXKM_Kot8P3uFAbtXUS1Y1ySWDwT0jeT4QDTcN8LXhOWZftGDq3Qx2s0Jz7A2qXZklcmwMO0.kcWsJ4.20.MPzyBFw.v0YehJ2Z2NE5YxkTqaEfN7kqykzwExPhaCp1QiIZ3Hd0wgS6WsgCgatChq0jeqqF0cqIUVCRYGR2J1OF7A2G2xWzkEv.CZGbUfSZoLOOt6QO.2U0e_8ll2QLMal9VmGJtIGUXbjNEOTpCC2ZHrKkgXc0BDHmll8QeNB1R80vpYgL8iWZ5pxPS7AtXAAF4DaNKudcQix9BVy7uB_c6YNuWoxDGi8PGgt.kGvm2_efpOLPm.g4SHJspVMadzYYf02YZPvefvXfxUHghKTBuubyrKx492T0BzV8IJ7sqOOCFfVTm85D72r8qbATPGBlhSI2gyXsoa.jMEzIarxUnGeBQpUcA6oAN9WjX3za6Lu97s7hBAAaB1p64G7LC2.tH8jPEIptJqFAEBmeAXCbTB9Zd9n481T4ba55WboUR7yDGzoMnHZeUv85fGpmf7O.n0CZ53KBU8jNkbb3vqJhIfXCR1cevEdrz2DL0UyKobdazQJEypdKmdFUuSpS9SdzUhG0zL_nYWkUJT8.ya6FFOSFum9sbib20mKEE67mw3UVaMQNiiaIR5FJUdpjEAp5FOddxXIY0LPpCKXHkxCUk8IvwRzTueq_XEnXsL7OVj3IafE..YSUXjD138_FGBGAt9DD9xQ.yQKgL0E5qMPsNkbiuiazy.lBULSb390Rb54d7p8bmmAiKfybo7m_UZxtvHTojxrvNviQT1ufCGnxiglTb22NXCT5pvBOO4z0xhRMxOO7OwvF.B0XnSxSMSwVFMpyP.LFbiX6xsX5DX7l3hD_go24qv7r20407sHBhiKdR9Bqp_lmPZVPKVpA2hIGsvFEy9YN0OUpJX6z53uFuiEdA3jp4727JC4yuMSsPGfx1Iv6r3xllTLSFcct6q_R_DjE5zuCFeBZ.UWMCdqT8BHK_.nJivd60hULx4Z821VMg0Q1cbXvrmX5a2ooNjfMv1QqQgJFZgFfn62ojhaBiC_wMiaZwqPlTHJDn1SSGcWAN.5_ulZ29Xcv9Gui772k_b0l2ljiDmESsDvTs2JG9DW4SltcpVzN052wIXk2L.3Y5L3MTlFR5RLwOWsWIrfImZoFzQfJji5r7ezvNtXihQQ.DcQVBs9j4M06sE99FNbOHj0MbmyhJtn3ACfHVris40Lvt9TLGoRR4bhO_cTLXCo.GXiQg40UYgtrxadcqr4IGpZtWIjTx5nxSKiHNo9Ypdc60XM1irwmRNO.A0cIzm23KZIViEmNqttZicm48iUi0Qmjg3TD2.079qa4uWERdqvlOA6VixsprDaq5hNTEDYDzltyEkqIJau9hcjgA4VBUPfHbk0kRp5n1GAqYb8dXV15IvXJ7raZPAX4xf.c9TXRlnGvPSPvVpoEnH53gEEc7fmDQuyPHRpDv6Di0CyyYubByW4O.P8a_1_YUUHvZeFfhZ8HkhkM9Hl8AHm7jlM5bERJHXs7Wwrosr4m5lOF9zNbzLT7JPvNwO3UqXufL.lsLAXF_AMUDokHrLzCTTrE5ctYgylJGogsrjgf2Io_MoDR0rz5mxYnb5lvt3YDgJWvNEezvlWri6aES5xusjWWhuceheN_I0NrtIvlia0B9o9Q54Hu3QzbhAFPrhCx8N2lJ8xTtNlXmAguAlPZpwH0DMsGWMl.uaN4kKvVRAwh1a5qzjFnqsIH"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/g/orchestrate/chl_page/v1?ray=9141baeb2ef5482e';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/lookup\/doi\/10.1136\/hrt.39.3.233?__cf_chl_rt_tk=.iTgeZN2JqbdSX6bpD.InfeJFjt17OqxceAPcXL3d1M-1739920641-1.0.1.1-0JeAlcpARE5ZzERRmrIvuIffEAK4oDmp6aTGkIYYdbw" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>