A 59-year-old female with no prior cardiac diagnosis presented to our hospital with 3 days of intermittent chest pain. Her cardiac risk factors included hypertension, hypercholesterolaemia, elevated body mass index, and impaired glucose tolerance. Her medical history was also significant for asthma, gastro-oesophageal reflux disease and depression. Cardiovascular examination was unremarkable with no signs of heart failure.\nHer admission electrocardiogram (ECG) showed sinus rhythm, normal axis, narrow QRS (80 ms) with no ischaemic change or conduction defects (Figure ). The patient’s serum troponin recorded a peak measurement of 0.31 µg/L (cTnI n < 0.04 µg/L). Her biochemistry and blood panels were otherwise unremarkable with normal renal and liver function. Echocardiography showed normal biventricular size and systolic function, with normal valves.\nRadial approach coronary angiography was performed and the culprit vessel was shown to be the left circumflex artery (non-dominant) with a long 80% stenosis in the mid-portion. This was treated with deployment of a Synergy 3.0 ×24 mm drug eluting stent and restoration of TIMI 3 flow (Figure ). Medical management was elected for the patient’s residual moderate diffuse left anterior descending artery disease. The right coronary artery was non-obstructed.\nAt conclusion of the procedure, an oral load of ticagrelor 180 mg was administered. Three hours after, whilst convalescing in the coronary care unit, she began complaining of dyspnoea and four pauses were observed on telemetry over a 20 min period (Figure ), the longest being 18.5 s in duration (Figure ). Correspondingly, the patient had intermittent lapses of consciousness and underwent emergency right femoral venous temporary pacing wire insertion.\nTicagrelor was considered as the probable cause for the pauses, for that reason no additional ticagrelor was given after the loading dose and clopidogrel was commenced in place. No further brady-arrhythmias were detected in the subsequent 24 h and the un-utilized temporary pacing wire was removed. The patient was also discharged with aspirin, atorvastatin, perindopril, and amlodipine. A loop recorder (Medtronic Reveal LINQ) was implanted. Beta-blocker therapy was not prescribed in view of preceding events. Notably, there had not been a prior personal or family history of syncope.\nNo cardiorespiratory symptoms were raised during regular follow-up over 12 months with no arrhythmic events recorded on loop recorder interrogation.
In May of 2016, a 55-year-old male with history of hypertension, hyperlipidemia, and coronary artery disease (CAD) status after angioplasty of left anterior descending (LAD) artery 2 years ago presented to the emergency room (ER) with substernal chest pain. His cardiac enzymes were not elevated and electrocardiogram (EKG) showed normal sinus rhythm at a rate of 62 bpm with borderline AV conduction delay and right bundle branch block (RBBB) pattern (). The patient was only taking aspirin and had discontinued his statin due to muscle ache and metoprolol because of fatigue. His chest pain was relieved with sublingual nitroglycerin in the ER. In view of his significant history of CAD and typical anginal symptoms, patient underwent cardiac catheterization. It revealed 90 percent stenosis of the left mid circumflex coronary artery which was successfully stented with a drug-eluting stent. Right coronary artery (RCA) showed 50–60% stenosis while LAD showed patent stent. The patient recovered very well. After calculating the GRACE score, the patient was discharged on aspirin and ticagrelor as per the ACC guidelines. He was also prescribed rosuvastatin and metoprolol. Two months after PCI, the patient presented to his primary cardiologist due to worsening fatigue and intermittent dizziness. His metoprolol was stopped. In November, 2016, he was brought by emergency squad to the hospital due to worsening dizziness and diaphoresis at rest. He denied any h/o chest pain, palpitations, nausea, or loss of consciousness. The patient had stopped ticagrelor 1 day prior to this admission since he ran out of it. The patient requested a second opinion on this admission. On physical examination, his blood pressure was 126/66 mmHg and heart rate was regular at 42 beats per minute. The neck was supple with no carotid bruits and cardiac auscultation revealed 2/6 ejection systolic murmur in the left sternal border. Patient's EKG revealed second-degree type II atrioventricular (AV) block which was new (). His cardiac enzymes, thyroid stimulating hormone, serum potassium, and magnesium were within normal range. The patient did not receive ticagrelor further during the admission. Cardiac catheterization revealed RCA stenosis of 60–70% but no intervention was required as this was not the cause of the new onset heart block. We considered starting patient on oral theophylline on admission had the heart block not resolved within 24 hours. His second-degree heart block resolved 2 days after discontinuation of ticagrelor and his EKG showed sinus bradycardia (heart rate = 54 bpm) with borderline AV conduction delay with RBBB pattern () which was similar to his baseline EKG. Clopidogrel was started as an alternative P2Y12 platelet receptor inhibitor and aspirin was continued. He was discharged after an event monitor was placed.