POTS (Postural Orthostatic Tachycardia Syndrome) is a multisystem disorder characterized by the abnormal autonomic response to an upright posture, causing orthostatic intolerance and excessive tachycardia without hypotension. Recent reports suggest that a significant percentage of COVID-19 survivors develop POTS within 6 to 8 months of infection. Prominent symptoms of POTS include fatigue, orthostatic intolerance, tachycardia, and cognitive impairment. The exact mechanisms of post-COVID-19 POTS are unclear. Still, different hypotheses have been given, including autoantibody production against autonomic nerve fibers, direct toxic effects of SARS-CoV-2, or sympathetic nervous system stimulation secondary to infection. Physicians should have a high suspicion of POTS in COVID-19 survival when presented with symptoms of autonomic dysfunction and should conduct diagnostic tests like the Tilt table and others to confirm it. The management of COVID-19-related POTS requires a comprehensive approach. Most patients respond to initial non-pharmacological options, but when the symptoms become more severe and they do not respond to the non-pharmacological approach, pharmacological options are considered. We have limited understanding and knowledge of post-COVID-19 POTS, and further research is warranted to improve our understanding and formulate a better management plan.

Objective Atrial fibrillation (AF) weekend hospitalizations were reported to have poor outcomes compared to weekday hospitalizations. The relatively poor outcomes on the weekends are usually referred to as ‘weekend effect’. We aim to understand trends and outcomes among weekend AF hospitalizations. The primary purpose of this study is to evaluate the trends for weekend AF hospitalizations using Nationwide Inpatient Sample 2005–2014. Hospitalizations with AF as the primary diagnosis, in-hospital mortality, length of stay, co-morbidities and cardioversion procedures have been identified using the international classification of diseases 9 codes. Results Since 2005, the weekend AF hospitalizations increased by 27% (72,216 in 2005 to 92,220 in 2014), mortality decreased by 29% (1.32% in 2005 to 0.94% in 2014), increase in urban teaching hospitalizations by 72% (33.32% in 2005 to 57.64% in 2014), twofold increase in depression and a threefold increase in the prevalence of renal failure were noted over the period of 10 years. After adjusting for significant covariates, weekend hospitalizations were observed to have higher odds of in-hospital mortality OR 1.17 (95% CI 1.108–1.235, P < 0.0001). Weekend AF hospitalizations appear to be associated with higher in-hospital mortality. Opportunities to improve care in weekend AF hospitalizations need to be explored.

Atrial Fibrillation is a common arrhythmia affecting 6 million people in the United States and 33 million people worldwide, associated with significant morbidity. Whereas restoration and maintenance of sinus rhythm can translate into clinical benefit, early intervention in course of the disease can influence success and efficacy of intervention has been speculative and uncertain over past decade despite several literature and scientific studies. During past three decades catheter and surgical ablation of AF have evolved from an investigational status to a widely offerred definitive treatment now. With recent advances in mapping technology, ablation energy delivery, better understanding of pathogenesis and mechanism of AF there has been a paradigm shift in clinical decision making, patient selection, patient-physician discussion about various rhythm control strategy due to an ever improving safety and efficacy of the procedure. In this chapter we will briefly review the landmark clinical trials that has changed the outlook towards rhythm control strategy beginning from early trials such as AFFIRM, telling us rhythm control was no better than rate control to recent studies and EAST AFNET, which showed benefits of rhythm control. We will discuss differences in ablation strategy, safety and efficacy between paroxysmal AF vs. Persistent/Longstanding Persistent AF from a trigger and substrate view and pulmonary vein and non pulmonary vein targets for ablation. We will also elaborate on different energy sources for ablation such as Radiofrequency (RF), Cryoablation, newer ablation techniques such as Vein of Marshall alcohol ablation, High Power short duration ablation, Pulsed Field Ablation, Surgical ablation and Hybrid Convergent Ablation etc. Since this chapter is mostly intended towards diagnosis and management of AF in twenty-first century, authors have restricted mainly to recent developments only and purposefully have not expanded on already established preexisting knowledge about topics such as pharmacological rhythm control, rate control, Atrio-Ventricular node ablation with pacemaker implantation, direct current cardio version etc. In conclusion, with recent emerging evidence, importance of rhythm control is being increasingly recognized. Catheter ablation is more commonly performed with improving safety and efficacy. There are newer technology and ablation strategy available and should be offered to patient while discussing a comprehensive management of AF with careful review of risk benefit analysis.

Tizanidine is an alpha-2 adrenergic agonist used commonly by medical professionals to treat patients' chronic spasticity, muscle spasms, and neuralgia usually associated with myofascial components. This medication is also used very frequently in detoxification centers on patients treated for analgesic withdrawal, especially those who are suffering from rebound headaches due to the discontinuation of analgesics. Tizanidine is metabolized in the human body by the cytochrome P450 CYP1A2. On the other hand, ciprofloxacin is a common antibiotic belonging to the class of fluoroquinolones and is used to treat various infections. Ciprofloxacin inhibits the bacterial DNA-gyrase enzyme resulting in the destruction of the organism. Ciprofloxacin is also an inhibitor of the cytochrome P450 CYP1A2. Even though these two medications show obvious interaction still, however, both these medications are often prescribed together, and their interactions/contraindications are often overlooked by many physicians and other providers. We hereby describe the case report of the interaction between tizanidine and ciprofloxacin, along with the adverse outcome related to the concomitant use of these two drugs.