Heart Failure in ARVCD

In the first follow-up studies of ARVC/D patients, heart failure was described as a rare event. In 1987

Blomstrom-Lundqvist et al. reported three cases of right heart failure among 15 patients with ARVC/D observed for 1.5-28 (mean 8.8) years [3]. Two of them died, one suddenly, the other due to congestive heart failure. The prognostic importance of heart failure was raised by Pinamonti et al. in 1992, who observed significantly higher mortality of patients who presented heart failure symptoms than in patients with arrhythmias (p=0.038) [4]. Heart failure was observed by Peters et al. in 13 patients (11%) of a consecutive cohort of 121 patients with ARVC/D over a period of 12 years [5]. Three of them died and three others underwent or were waiting for heart transplantation. A review of the literature up to 1999 indicated that 46% of cardiac deaths in clinical series of patients with ARVC/D were due to heart failure. Later this proportion began to change. Patients who died due to heart failure or underwent heart transplantation in large clinical series reported in 2003-2005 represented 47%-66% of all cases of cardiac terminal events (Table 21.1) [5-8]. The mean age of patients who died because of severe pump failure or underwent heart transplantation was significantly higher than those who died suddenly both in the pathologic study of Basso et al. [9] and clinical series of Peters [10].

Isolated right ventricular failure in ARVC/D, being a result of dilatation, wall thinning and wall motion dysfunction due to loss of cardiomyocytes,

Table 21.1 • Risk of nonsudden cardiac death in patients with ARVC/D - a systematic review of literature

Author

No pts

Follow-up

HF % pts

NSCD+OHT

(years, mean)

No pts

Blomstrom-Lundqvist, 1987 [3]

15

8.8

20%

1

Peters, 1999 [5]

121

4-8

11%

3+3

Hulot, 2004 [6]

130

8

16%

5+2

Lemola,2005 [7]

61

4.6

11%

2+5

Corrado, 2003 [8]

132 (ICD)

3.3

4

HF, heart failure; NSCD, nonsudden cardiac death; OHT, orthotopic heart transplantation; pts, patients

represents a unique clinical situation where right heart failure is accompanied by low pulmonary pressure. As only 5 mm Hg is a sufficient pressure difference to provide adequate pulmonary flow, even severe damage of the right ventricle (RV) muscle has no apparent effect on hemodynamics. Paradoxical ventricular septum motion and prominent right atrial contraction provide functional compensation enabling normal physical activity for a long time. It is not well known what factors are a trigger for symptoms of right ventricular failure. Left ventricle (LV) damage, superimposed myocarditis, atrial fibrillation, incessant ventricular tachycardia, and RV thrombosis are the most frequent mechanisms bringing mild RV heart failure symptoms.

Extensive damage of the RV leading to isolated RV failure symptoms is more frequent in the fatty variant of the disease, characterized by intensive fatty infiltration of the RV, reaching the endocardium and sparing the LV and septum (Fig. 21.1),

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Fig.21.1 • ARVC/D-fatty variant. a Heart removed at cardiac transplantation. bTwo-dimensional echocardiogram of an apical four-chamber examination. Dilated right ventricle and regular diameter of left ventricle whereas biventricular failure mimicking dilated cardiomyopathy, is observed in the fibro-fatty variant [11].

LV damage in patients with ARVC/D is known to be a risk factor of SCD as well as congestive heart failure and non-SCD [7, 12,13]. It is not unusual, particularly in the fibrofatty variant of the disease. LV damage is observed in up to 55% patients and is characterized by focal hypokinesis at the apex and infero-posterior wall without severe chamber dilatation or, less frequently, by diffuse hypokinesis and moderate dilatation (Fig. 21.2) [14]. Macroscopic and histo-logical involvement of the LV was observed even in 76% of hearts with ARVC/D and was characterized by similar abnormalities to those found in the RV with a predominance of fibrosis [15]. In some genetic forms of the disease, LV damage appears early and leads to a clinical picture of dilated cardiomyopathy more frequently than in other forms of the disease. In ARVD8 (desmoplakin gene mutation) LV involvement was seen in 43%, and heart failure symptoms in 14% of patients [16]. LV damage is also a typical feature of ARVD4, although severe manifestation of symptoms was reported only in patients involved in sport activities [17].

A possible mechanism of progressive right or biven-tricular failure, triggering apoptosis and necrosis due to Ca2+ ions overloading, is inflammation. Inflammatory cells (CD43-positive lymphocytes) are detected in two-thirds of cases with the fibrofatty variant of the disease [11]. Fontaine and colleagues demonstrated progression of the disease due to superimposed inflammation [18]. Although viral myocarditis was demonstrated only in single cases, increased susceptibility to infection

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GAIH 82 59 «BPM

  1. 21.1 • ARVC/D-fatty variant. a Heart removed at cardiac transplantation. bTwo-dimensional echocardiogram of an apical four-chamber examination. Dilated right ventricle and regular diameter of left ventricle
  2. 21.2 • Left ventricular (LV) involvement in ARVC/D. Parasternal long-axis apical view. Apical aneurysm of LV

(arrow)

with cardiotropic viruses in the diseased myocardium cannot be excluded [19].

The most important clinical marker of diffuse RV lesions with LV involvement, significantly associated with thromboembolism and heart failure, is atrial fibrillation (AF). Supraventricular tachyarrhythmias are not rare in ARVC/D. Supraventricular tachycardia, paroxysmal atrial tachycardia, and AF are reported in clinical series observed in 14%-28% cases [7,20-21]. Patients with supraventricular arrhythmias are older and have a longer disease duration. Whereas supraventricular tachycardias are probably a result of electrical instability of the right atrial myocardium, AF is tightly connected with advanced RV damage and often accompanied by LV impairment. Lack of atrium contraction worsens RV function, resulting in apparent heart failure symptoms [22].

Fig. 21.4 • Apical four-chamber view. Cloud of echoes resulting from stagnant blood - echogenic blood - in right chambers

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Fig.21.3 • a Apical four-chamber view.Thrombus in the RV apex (arrows). b RV outflow tract with thrombus from parasternal long axis view (arrow). Ao, aorta; LV, left ventricle; RA, right atrium; RV, right ventricle. From [27]

There are very few reports available on throm-boembolic complications in patients with ARVC/D. Most of them describe atrial thrombus formation in patients with the extensive form of the disease and with concomitant AF [23-26]. RV thrombosis is usually associated with severe dilatation of the RV and significant wall motion abnormalities [27]. The incidence of thromboembolic complications in ARVC/D seems to be less frequent than in patients with left ventricular failure of other causes (annual incidence: 0.48 vs. 1.9%, respectively) [27]. Despite their rare occurrence, these complications should not be underestimated because their clinical presentation is usually quite serious. Both pulmonary embolism with fatal outcome and severe heart failure in case of RV outflow tract thrombosis have been observed (Fig. 21.3). In patients with a severely dilated and akinetic RV, spontaneous echocardiographic contrast due to stagnant blood may be also observed (Fig. 21.4).

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