Reversible sick sinus syndrome due to sinus node artery ischaemia in an elderly woman: a case report

Sick sinus syndrome often necessitates permanent pacemaker implantation; however, when sinus node artery ischaemia is the cause, sinus node dysfunction may be reversible. While age-related fibrosis is generally considered the main mechanism, ischaemia should also be recognized as a potential aetiology.

An 80-year-old woman with breast cancer, hypertension, and diabetes mellitus presented with dyspnoea. Electrocardiography showed marked bradycardia at 38 beats per minute (b.p.m.) without ST-segment changes. Chest radiography revealed a cardiothoracic ratio of 61% with mild pulmonary congestion, and echocardiography showed preserved left ventricular ejection fraction (>60%) without wall motion abnormality. Although referred for pacemaker implantation, the acute onset of severe bradycardia together with multiple coronary risk factors prompted coronary angiography, which demonstrated 99% stenoses in the proximal right coronary and proximal left circumflex arteries, and 90% in the mid left anterior descending artery. Flow delay was noted in the sinus node branch of the right coronary artery. Percutaneous coronary intervention of the proximal right coronary artery promptly restored sinus rhythm during the procedure. She has since remained stable with a sinus rate of 70 b.p.m. for 1 year without pacing.

Despite no chest pain or ST changes, the acute presentation and multiple coronary risk factors suggested an ischaemic aetiology. Intermittent right coronary artery impairment, bradycardia-facilitated collateral flow, and repolarization abnormalities likely obscured typical ischaemic signs. This case highlights the importance of ischaemic evaluation before pacemaker implantation, even in elderly patients.