Table 1.

Summary of studies reporting prognostic effects of atrial arrhythmias in patients with PH and outcomes with rhythm or rate control. NR—not reported.

Study	Study Design	Study Size	Patient Population	Primary Endpoint and Results	Type of Arrhythmia	Effect of Arrhythmia	Effect of Rhythm Control
Tongers et al., Am Heart J, 2007 [14]	Retrospective, observational, single-center	231	Consecutive patients followed for PAH or inoperable CTEPH	Incidence of SVA 31 episodes of SVA were observed in 27 of 231 patients (cumulative incidence, 11.7%; annual risk, 2.8% per patient)	AFL (n = 15), AF (n = 13), and AVNRT (n = 3)	SVA onset was associated with clinical deterioration and right ventricular failure (84% of SVA episodes); outcome was strongly associated with the type of SVA and restoration of sinus rhythm	Mortality was 6.3% (follow-up 26 ± 23 months) when sinus rhythm was restored (all cases of AVNRT and AFL), but was 82% with sustained AF (follow-up 11 ± 8 months)
Showkathali et al., Int J Cardiol, 2011 [22]	Retrospective, observational, single-center	22	Patients with AFL and PAH or CTEPH	Success of typical atrial flutter ablation AFL ablation was acutely successful and without complications. Three patients had recurrence and underwent successful redo procedures without further recurrence	Typical atrial flutter	NR	Functional class improved in 9 and remained the same in 11 patients; 6MWT was 275 ± 141 m before and increased to 293 ± 146 m following ablation (p = 0.301)
Luesebrink et al., Heart Lung Circ, 2012 [27]	Retrospective, observational, single-center	38 with PAH; 196 controls	Patients undergoing ablation of cavo-tricuspid isthmus-dependent flutter with an 8 mm RF ablation catheter	Influence of PAH on typical atrial flutter ablation procedure Acutely successful ablation in all patients; patients with severe PAH had a significantly longer procedure time (78 ± 40 min vs. 62 ± 29 min; p = 0.033), total ablation time (20 ± 11 min vs. 15 ± 9 min; p = 0.02), and more ablation lesions (26 ± 16 vs. 19 ± 12; p = 0.018) compared to patients without PAH	Typical atrial flutter	NR	NR
Bradfield et al., JCE, 2012 [24]	Retrospective, observational, single-center	12	Consecutive patients with severe PAH (systolic pulmonary artery pressure > 60 mmHg) and AFL referred for ablation (4 congenital, 2 CTEPH, 6 PAH)	Describe flutter ablation in patients with severe PAH Acute success was obtained in 86% of procedures. Complications were seen in 14%. A total of 80% (8/10) of patients were free of AFL at 3 months; 75% (6/8) at 1 year	Typical atrial flutter	NR	SPAP decreased from 114 ± 44 mmHg to 82 ± 38 mmHg after ablation (p = 0.004); BNP levels were lower post ablation (787 ± 832 pg/mL vs. 522 ± 745 pg/mL, p = 0.02)
Kamada et al., Sci Rep, 2021 [26]	Retrospective, observational, single-center	23	13 patients with congenital heart disease; 6 with idiopathic or other PAH; 3 with CTEPH; and 1 with hemodialysis-associated PH (group 5)	Procedural success rate; short- and long-term clinical outcomes Single-procedure success, 83%; 94% (17/18) in typical atrial flutter; 73% (8/11) in atrial tachycardia (AT); and 100% (1/1) in atrioventricular nodal reentrant tachycardia.	Typical atrial flutter, atrial tachycardia, and AVNRT	NR	Antiarrhythmic drugs, serum brain natriuretic peptide levels, and number of hospitalizations significantly decreased after RFCA SVT after the last RFCA was a significant risk factor of mortality (HR, 9.31; p = 0.016).
Zhou et al., Front Physiol, 2021 [17]	Retrospective, observational, single-center	71	Consecutive PH patients with SVA who were scheduled to undergo catheter ablation	Feasibility and long-term outcomes of catheter ablation in PH patients with SVA Acute success in 54, complications in 4 (6.7%); during median follow-up of 36 (range, 3–108) months, 7 patients with atrial flutter experienced recurrence (78.3% success rate)	Typical atrial flutter (n = 33, 43.5%) was the most common SVT type, followed by atrioventricular nodal reentrant tachycardia (n = 16, 21.1%)	NR	NR
Cannillo et al., Am J Cardiol, 2015 [4]	Retrospective, observational, single-center	77	Consecutive patients with PAH without history of SVA	All-cause mortality and re-hospitalization During a median follow-up of 35 months, 17 patients (22%) experienced SVA. The primary endpoint occurred in 13 patients (76%) in the SVA group and in 22 patients (37%) in the group without SVA (p = 0.004)	Persistent AF (8 patients, 47%); permanent AF (3, 17%); paroxysmal SVA (3, 17%: 2 with atrial ectopic tachycardia and 1 with atrioventricular nodal re-entry tachycardia); right atrial flutter (2, 12%); and paroxysmal AF (1, 6%)	SVA onset was associated with the worsening of functional class, NT-proBNP, 6 min walk distance, TAPSE, and DLCO; 9 patients (53%) among those with SVA died compared with 8 (13%) among those without (p = 0.001)	NR
Wen et al., Am J Card, 2014 [1]	Prospective, two-center cohort study	280	Consecutivepatients > 18 years of age with IPAH at 2 national referral centers in China	All-cause mortality Patients who developed SVAs had a significantly higher mortality than those who did not; estimated survivalat 1, 3, and 6 years was 85%, 64.2%, and 52.6% vs. 92%, 81.9%, and 74.5%,respectively; p = 0.008	Atrial fibrillation (n = 16), atrial flutter (n = 13), and atrial tachycardia (n = 11)	In most patients (97.5%), the onset of SVA resulted in clinical deterioration or worsening right-sided cardiac failure	Patients who developed permanent SVA had a significantly lower survival rate than patients with transient SVA (p = 0.011) or without SVA (p < 0.001); survival was not statistically different between patients with transient SVA and those without SVA (p = 0.850)
Olsson et al., Int J Cardiol [12]	Prospective, single-center cohort study	239 (PAH, n = 157; inoperable chronic thromboembolic pulmonary hypertension, n = 82)	Consecutive patients ≥ 18 years of age treated for PAH or inoperable CTEPH	Incidences of AF and AFL The cumulative 5-year incidence of new-onset atrial flutter and fibrillation was 25.1% (95% confidence interval, 13.8–35.4%)	AF 50% and AFL 50%	AF and AFL were frequently accompanied by clinical worsening (80%) and right heart failure (30%); new-onset atrial flutter and AF were independent risk factors for death	Stable sinus rhythm was successfully re-established in 21/24 (88%) with atrial flutter and in 16/24 (67%) with atrial fibrillation Higher mortality was observed in patients with persistent AF compared to patients in whom sinus rhythm was restored (estimated survival at 1, 2, and 3 years was 64%, 55%, and 27% versus 97%, 80%, and 57%, respectively)
Smith et al., Pulm Circ, 2018 [25]	Retrospective, observational, multi-center	297 (group 1 PAH, n = 266; CTEPH, n = 31)	All patients in a healthcare system with PAH or CTEPH (excluding those who had undergone thromboembolectomy)	AF/AFL occurrence and survival 79 (26.5%) developed AF/AFL, either before or after a diagnosis of PH or CTEPH	AF in 46 (58.2%), atrial flutter in 25 (31.6%), and instances of both in 8 (10.1%)	AF/AFL was associated with a 3.81-fold increase in the hazard of death (95% CI, 2.64–5.52; p < 0.001) Mortality risk was present, whether paroxysmal or persistent AF/AFL	NR
Ruiz-Cano et al., Int J Cardiol, 2010 [23]	Retrospective, observational, single-center	282 patients with PH; not reported but implied 28 with arrhythmias	Group 1 PAH: 6 patients (26.1%) had idiopathic PAH; 7 (30.4%), a connective tissue disease; 6 (26.1%), toxic oil syndrome; and 4 (17.4%), Eisenmenger syndrome	Safety and efficacy of EPS Efficacy 100% for AVNRT and 95% for typical flutter; safety not reported	AF (n = 12, 42.8%); atypical flutter (n = 7, 25%); typical flutter (n = 5, 17.8%); andAVNRT (n = 4, 14.2%)	Most episodes of SVA (82%) were symptomatic with clinicalworsening or RV failure Clinical deterioration was not observed in patients with AVNRT	Restoration of SR was associated with a clinical improvement in all the patients, with an average increase of 196 ± 163 m in 6MWT