Inappropriate sinus tachycardia

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Inappropriate sinus tachycardia
ECG of 33-year-old female showing sinus tachycardia at 132 bpm
SpecialtyCardiology
SymptomsPalpitations, chest discomfort, tiredness, shortness of breath, and lightheadedness[1]
ComplicationsRare[2]
Usual onsetSudden[2]
DurationLong-term[2]
CausesUnclear[3]
Diagnostic methodAfter ruling out other possible causes[2]
Differential diagnosisPostural orthostatic tachycardia syndrome, other supraventricular tachycardias including sinus tachycardias due to anemia or high thyroid[3][4]
TreatmentPhysical training, beta blockers, calcium channel blockers, ivabradine, ablation[5][2]
PrognosisNo effect on life expectancy[2][4]
Frequency1% of adults[1]

Inappropriate sinus tachycardia (IST) is sinus tachycardia results in symptoms and without an identifiable cause.[3] Symptoms may include palpitations, chest discomfort, tiredness, shortness of breath, and lightheadedness.[1] Onset is typically sudden and symptoms may persist for years.[2] Often quality of life is affected; though, it rarely results in long-term heart problems such as cardiomyopathy.[3][2]

The cause is unclear, though it may occur as a postviral syndrome.[3][2] Proposed mechanisms include an abnormal sinus node, autonomic dysfunction, autoimmune, and abnormal baroreflex.[3][1] Diagnosis requires other causes being ruled out via a Holter monitor and heart ultrasound.[3] It generally results in a heart rate at rest above 100 beats per minute with an average heart rate over a day above 90.[1][2] Heart rate may be either persistently high or increase significantly with minor triggers such as psychological stress or exercise, but is not exclusively related to position.[5][2][4]

Management may involve limiting activity; though, physical training is recommended, and avoiding caffeine and alcohol.[2] Medications may include beta blockers, calcium channel blockers, or ivabradine, but are not always effective.[5][2] While ablation is used, outcomes are mixed.[1] Counselling may help some people.[4] The condition may resolve after months or years.[6][2] Long-term it does not appear to affect life expectancy.[2][4]

Inappropriate sinus tachycardia affects about 1% of middle aged adults.[1] It occurs most commonly in young adults between the age of 15 and 45.[3][5] Women are affected four times more often then men.[3][5] The condition was first described by Codvelle in 1939; though, it did not become more commonly known until the 1970s.[3][4]

Signs and symptoms

Palpitations occur in roughly 90%. Other symptoms may include chest pain, fatigue, shortness of breath, presyncope, syncope,[1] reduced exercise tolerance, anxiety, panic attacks, and headaches. These symptoms are usually associated with an elevated heart rate. While some have persistently elevated sinus rates, others have intermittent episodes with normal heart rates in between.[7]

Inappropriate sinus tachycardia is a long-term condition that has a negative impact on quality of life.

Causes

The exact cause is unknown. Several mechanisms have been suggested, including increased sympathetic or decreased parasympathetic drive, increased intrinsic heart rate, dysfunctional neurohormonal modulation, ectopic sinus node activity, and beta-adrenergic receptor autoantibodies. Some data show an abnormal response to autonomic stimulation as a result of tissue/cell level changes (intrinsic mechanism), whereas others show a disruption of the autonomic stimulation itself with normal tissues/cell level findings (extrinsic mechanism). It is possible that both mechanistic theories are correct because, despite sharing a single common pathway of sinus tachycardia, individual patients' underlying mechanistic etiologies may differ.[8]

Mechanism

Over 15 electrical currents tightly control the sinus node. The calcium clock and the funny current appear to be the most important currents in regulating sinus node rate. Sinus activation and thus heart rate is regulated further through the autonomic nervous system. At rest, the sinus node is primarily regulated by tonic and phasic parasympathetic activation in normal, healthy individuals. Exercise causes vagal activation, sympathetic activation, and increases in catecholamine levels, which raises sinus rates.[2][9] Any aspect of regular regulatory processes influencing sinus rate may be compromised in patients with IST.[2]

Diagnosis

Inappropriate sinus tachycardia is diagnosed when there is persistent or recurrent sinus tachycardia on a 12-lead electrogram or long-term monitoring that is not explained by other means. Invasive testing, such as electrophysiology studies, are not helpful in making the diagnosis, but they may be useful in ruling out a concomitant supraventricular tachycardia mechanism.[2] Inappropriate sinus tachycardia is a diagnosis of exclusion that is rarely made in an asymptomatic patient.[3]

The following criteria are commonly used to define inappropriate sinus tachycardia:[10]

  1. The axis and morphology of the P wave during tachycardia similar to or identical to that experienced during sinus rhythm
  2. A resting heart rate of 100 beats per minute or an increase in heart rate of 100 beats per minute with minimal exertion
  3. Excluding any potential secondary causes of sinus tachycardia
  4. Ruling out atrial tachycardias
  5. Palpitations or presyncope (or both) symptoms that have been clearly linked to resting or easily induced sinus tachycardia.

Secondary causes of sinus tachycardia must be ruled out and corrected if present. A full endocrinology evaluation for disease entities such as hyperthyroidism, pheochromocytoma, and diabetes mellitus with evidence of autonomic dysfunction should be included in the evaluation for inappropriate sinus tachycardia.[10]

Differential diagnosis

Inappropriate sinus tachycardia is a diagnosis of exclusion.[7] Upon exertion, an inappropriate heart rate response of sinus tachycardia can be seen in some inborn errors of metabolism that result in metabolic myopathies, such as McArdle disease (GSD-V)[11][12] and hereditary myopathy with lactic acidosis (Larsson–Linderholm syndrome).[13][14]

Sinus tachycardia is a feature of both postural orthostatic tachycardia syndrome and Inappropriate sinus tachycardia. In POTS, there's an abnormal response by the autonomic nervous system when standing up. POTS symptoms are most common when the patient is upright. POTS syndromes and inappropriate sinus tachycardia may overlap, raising the possibility of shared mechanisms. The most common symptoms of POTS are dizziness and, on occasion, syncope, which are also common in IST.[3]

Sinus node reentry is another differential diagnosis for Inappropriate sinus tachycardia. An ectopic atrial rhythm occurring near the sinus node may also mimic Inappropriate sinus tachycardia. Syncope or pre-syncope may occur in IST patients and be the dominant symptom, with associated prodromal symptoms such as diaphoresis and visual blurring, leading to the diagnosis of vasovagal syncope and the diagnosis of IST being overlooked.[3]

Treatment

There are numerous treatment, which are frequently combined with lifestyle and dietary changes. It is advised to avoid triggers such as stimulants including caffeine and nicotine, and alcohol.[7]

Controlling symptoms and decreasing rate, remains a challenge, given the ambiguity of the syndrome itself. Controlling the heart rate, on the other hand, does not always result in the elimination of symptoms. Controlling sinus rate in someone who is asymptomatic is debatable. Often no single therapy completely and effectively reduces heart rate and symptoms, which is likely due to the problem's complexity and a lack of a complete understanding of the causes.[2]

Sleeping with the head of the bed elevated and increasing plasma volume through generous salt and fluid intake can be beneficial with minimal risk. In those with venous pooling, compression stockings can offer additional benefits; however, adherence often becomes an issue. These lifestyle changes may alleviate symptoms and prevent reflex tachycardia, which is especially common in chronic dehydration. In overt psychosomatic complaints, it is acceptable to consider a psychiatric evaluation.[15]

Medication

Medication should be started gradually, with the goal of lowering HR and improving symptoms. A trial-and-error approach typically employed.[15]

β-Blockers are the first-line treatment for Inappropriate sinus tachycardia. Β-blockers, in general, alleviate symptoms. β-adrenergic receptor sensitivity and elevated catecholamine levels throughout orthostatic stress usually respond well to a variety of β-blockers. Nondihydropyridine calcium channel blockers have demonstrated a modest benefit in symptom control of IST in people with contraindications to β-Blockers.[15]

Other drugs, such as sympatholytics and cholinesterase inhibitors like pyridostigmine, have very limited evidence. There have been no randomized controlled trials regarding the use of these drugs in inappropriate sinus tachycardia, and all, with the possible exception of β-blockers, should be considered off-label indications.[15]

Ivabradine has been shown to reduce HR, improve exercise capacity quantitatively, and reduce subjective symptom burden. The drug appears to have a lower proarrhythmic risk and is well tolerated. Ivabradine shows great promise as the possible therapy of choice for beta-blocker intolerant or suboptimally responsive patients with a chronic condition that frequently becomes clinically problematic in management.[16]

Procedures

There are no guidelines regarding who should be considered for invasive treatments. Interventions range from surgical sinus node exclusion to sinus or AV node radiofrequency catheter ablation, which typically is followed by permanent pacemaker implantation and, in recent years, radiofrequency sinus node modification.[17]

Several trials have described sinus node modification or ablation. Primary success rates are generally good, however, there is a high rate of symptom recurrence and significant complication rates. These complications include the need for permanent pacing, transient superior vena cava syndrome, and temporary or permanent paralysis of the phrenic nerve. Furthermore, sinus node modification or ablation may not alleviate all symptoms. There is also no consensus on the best approach, which includes modifications or ablation, open chest versus conventional intravascular access, and mapping methods. Finally, there has been no evidence of symptomatic improvement over time.[18]

Outlook

IST is generally benign. One possible reason for a favourable prognosis is that, while IST patients have faster heart rates, their heart rate slows slightly during sleep as well as during various diurnal patterns. Long-term consequences are few, but published studies are small, follow-up is limited, and populations are varied. Although there have been isolated reports, IST is rarely associated with tachycardia-induced cardiomyopathy.[2] Symptoms may last for years but tend not to progress and may eventually fade away.[19]

Epidemiology

Inappropriate sinus tachycardia, defined as 24-hour average HR > 90 bpm and HR > 100 bpm in a supine or sitting position, has a prevalence of 1.16% in the general population.[20] The epidemiology of Inappropriate sinus tachycardia is not well understood. IST can occur at any age, but it is most common in adolescents and young adults.[3] Inappropriate sinus tachycardia was previously thought to be a rare condition affecting young women, with health professionals being overrepresented. This characterization may better define the group of IST patients who are most symptomatic and/or likely to seek medical attention, as opposed to the entire cohort of Inappropriate sinus tachycardia patients.[19]

In IST, the most common comorbidities are psychiatric, including a history of depression in 25.6% as well as anxiety in 24.6%. Higher rates of diabetes mellitus, hypertension, and hypothyroidism have been identified in those with IST, though lower rates of hyperthyroidism have been observed. 28.2% of patients reported an event or physical condition preceding the onset of IST symptoms. Pregnancy was the most common identifiable initiating factor in IST patients (7.9%).[21]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Ali, Muzaffar; Haji, Abdul Qadir; Kichloo, Asim; Grubb, Blair P; Kanjwal, Khalil (2021). "Inappropriate sinus tachycardia: a review". Reviews in Cardiovascular Medicine. IMR Press. 22 (4): 1331–1339. doi:10.31083/j.rcm2204139. ISSN 2153-8174. PMID 34957774. S2CID 245466598.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 Olshansky, Brian; Sullivan, Renee M. (2013). "Inappropriate Sinus Tachycardia". Journal of the American College of Cardiology. Elsevier BV. 61 (8): 793–801. doi:10.1016/j.jacc.2012.07.074. PMID 23265330.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 Peyrol, Michael; Lévy, Samuel (September 2, 2015). "Clinical presentation of inappropriate sinus tachycardia and differential diagnosis". Journal of Interventional Cardiac Electrophysiology. Springer Science and Business Media LLC. 46 (1): 33–41. doi:10.1007/s10840-015-0051-z. ISSN 1383-875X. PMID 26329720. S2CID 23249973. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 "Inappropriate Sinus Tachycardia (IST)". Archived from the original on 27 April 2024. Retrieved 26 April 2024.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Ahmed, A; Pothineni, NVK; Charate, R; Garg, J; Elbey, M; de Asmundis, C; LaMeir, M; Romeya, A; Shivamurthy, P; Olshansky, B; Russo, A; Gopinathannair, R; Lakkireddy, D (21 June 2022). "Inappropriate Sinus Tachycardia: Etiology, Pathophysiology, and Management: JACC Review Topic of the Week". Journal of the American College of Cardiology. 79 (24): 2450–2462. doi:10.1016/j.jacc.2022.04.019. PMID 35710196.
  6. ↑ "Articles". Cedars-Sinai. Archived from the original on 29 September 2023. Retrieved 26 April 2024.
  7. ↑ 7.0 7.1 7.2 Ahmed, Adnan; Pothineni, Naga Venkata K.; Charate, Rishi; Garg, Jalaj; Elbey, Mehmet; de Asmundis, Carlo; LaMeir, Mark; Romeya, Ahmed; Shivamurthy, Poojita; Olshansky, Brian; Russo, Andrea; Gopinathannair, Rakesh; Lakkireddy, Dhanunjaya (June 21, 2022). "Inappropriate Sinus Tachycardia: Etiology, Pathophysiology, and Management: JACC Review Topic of the Week". Journal of the American College of Cardiology. Elsevier BV. 79 (24): 2450–2462. doi:10.1016/j.jacc.2022.04.019. ISSN 0735-1097. PMID 35710196. S2CID 249667656.
  8. ↑ Eckhardt, Lee L.; Hamdan, Mohamed H. (2020). "Inappropriate sinus tachycardia". Sex and Cardiac Electrophysiology. Elsevier. pp. 453–462. doi:10.1016/b978-0-12-817728-0.00040-1. ISBN 9780128177280. S2CID 235090095. Archived from the original on 2023-09-06. Retrieved 2024-04-22.
  9. ↑ Saltin, Bengt (2000). Exercise and Circulation in Health and Disease. Human Kinetics. ISBN 978-0-88011-632-9. Archived from the original on 2024-04-27. Retrieved 2024-04-22.
  10. ↑ 10.0 10.1 Lee, Randall J.; Shinbane, Jerold S. (1997). "Inappropriate Sinus Tachycardia". Cardiology Clinics. Elsevier BV. 15 (4): 599–605. doi:10.1016/s0733-8651(05)70364-7. ISSN 0733-8651. PMID 9403163. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  11. ↑ Lucia A, Martinuzzi A, Nogales-Gadea G, Quinlivan R, Reason S, et al. (International Association for Muscle Glycogen Storage Disease study group) (December 2021). "Clinical practice guidelines for glycogen storage disease V & VII (McArdle disease and Tarui disease) from an international study group". Neuromuscular Disorders. 31 (12): 1296–1310. doi:10.1016/j.nmd.2021.10.006. PMID 34848128. Epub 2021 Oct 28. Erratum: Lucia A, Martinuzzi A, Nogales-Gadea G, Quinlivan R, Reason S (February 2022). "Erratum to Clinical practice guidelines for glycogen storage disease V & VII (McArdle disease and Tarui disease) from an international study group [Neuromuscular Disorders 31 (2021) 1296-1310]". Neuromuscular Disorders. 32 (2): e3. doi:10.1016/j.nmd.2022.01.004. PMID 35140027. Epub 2022 Feb 6.
  12. ↑ Wakelin A (2017). Living With McArdle Disease (PDF). IAMGSD (International Association of Muscle Glycogen Storage Disease). p. 15. Archived (PDF) from the original on 2023-03-05. Retrieved 2024-04-22.
  13. ↑ Larsson, L. -E.; Linderholm, H.; Müller, R.; Ringqvist, T.; Sörnäs, R. (October 1964). "Hereditary metabolic myopathy with paroxysmal myoglobinuria due to abnormal glycolysis1". Journal of Neurology, Neurosurgery, and Psychiatry. 27 (5): 361–380. doi:10.1136/jnnp.27.5.361. ISSN 0022-3050. PMC 495765. PMID 14213465.
  14. ↑ Saltin, Bengt (2000). "Chapter 21: Circulatory Regulation in Muscle Disease". Exercise and Circulation in Health and Disease. Human Kinetics. pp. 271–279. ISBN 978-0-88011-632-9. Archived from the original on 2024-04-27. Retrieved 2024-04-22.
  15. ↑ 15.0 15.1 15.2 15.3 Femenía, Francisco; Baranchuk, Adrian; Morillo, Carlos A. (2012). "Inappropriate Sinus Tachycardia". Cardiology in Review. Ovid Technologies (Wolters Kluwer Health). 20 (1): 008–014. doi:10.1097/crd.0b013e31822f0b3e. ISSN 1061-5377. PMID 22143280. S2CID 22690743. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  16. ↑ Abed, H. S.; Fulcher, J. R.; Kilborn, M. J.; Keech, A. C. (April 5, 2016). "Inappropriate sinus tachycardia: focus on ivabradine". Internal Medicine Journal. Wiley. 46 (8): 875–883. doi:10.1111/imj.13093. hdl:2123/16696. ISSN 1444-0903. PMID 27059112. S2CID 11519527. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  17. ↑ KRAHN, ANDREW D.; YEE, RAYMOND; KLEIN, GEORGE J.; MORILLO, CARLOS (1995). "Inappropriate Sinus Tachycardia: Evaluation and Therapy". Journal of Cardiovascular Electrophysiology. Wiley. 6 (12): 1124–1128. doi:10.1111/j.1540-8167.1995.tb00391.x. ISSN 1045-3873. PMID 8720214. S2CID 44516317. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  18. ↑ Sheldon, Robert S.; Grubb, Blair P.; Olshansky, Brian; Shen, Win-Kuang; Calkins, Hugh; Brignole, Michele; Raj, Satish R.; Krahn, Andrew D.; Morillo, Carlos A.; Stewart, Julian M.; Sutton, Richard; Sandroni, Paola; Friday, Karen J.; Hachul, Denise Tessariol; Cohen, Mitchell I.; Lau, Dennis H.; Mayuga, Kenneth A.; Moak, Jeffrey P.; Sandhu, Roopinder K.; Kanjwal, Khalil (2015). "2015 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Treatment of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia, and Vasovagal Syncope". Heart Rhythm. Elsevier BV. 12 (6): e41–e63. doi:10.1016/j.hrthm.2015.03.029. ISSN 1547-5271. PMC 5267948. PMID 25980576. Archived from the original on November 7, 2023. Retrieved November 6, 2023.
  19. ↑ 19.0 19.1 Pellegrini, Cara N.; Scheinman, Melvin M. (2015-08-27). "Epidemiology and definition of inappropriate sinus tachycardia". Journal of Interventional Cardiac Electrophysiology. Springer Science and Business Media LLC. 46 (1): 29–32. doi:10.1007/s10840-015-0039-8. ISSN 1383-875X. PMID 26310298. S2CID 23969283. Archived from the original on 2023-11-07. Retrieved November 6, 2023.
  20. ↑ STILL, A; RAATIKAINEN, P; YLITALO, A; KAUMA, H; IKAHEIMO, M; ANTEROKESANIEMI, Y; HUIKURI, H (January 1, 2005). "Prevalence, characteristics and natural course of inappropriate sinus tachycardia". Europace. Oxford University Press (OUP). 7 (2): 104–112. doi:10.1016/j.eupc.2004.12.007. ISSN 1099-5129. PMID 15763524. S2CID 23711055.
  21. ↑ Shabtaie, Samuel A.; Witt, Chance M.; Asirvatham, Samuel J. (November 20, 2019). "Natural history and clinical outcomes of inappropriate sinus tachycardia". Journal of Cardiovascular Electrophysiology. Wiley. 31 (1): 137–143. doi:10.1111/jce.14288. ISSN 1045-3873. PMID 31749258. S2CID 208216050. Archived from the original on November 7, 2023. Retrieved November 6, 2023.

External links

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External resources
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